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LITHUANIAN SPORTS UNIVERSITY
FACULTY OF SPORTS BIO-MEDICINE
PHYSIOTHERAPY STUDY PROGRAME
MOHAMED ARSHADH YALAYAR SHAIK KADER SULTAN
EFFECT’S OF DIFFERENT MUSCLE STRETCHING TECHNIQUES ON
HAMSTRING MUSCLE FLEXIBILITY IN AMATEUR SOCCER
PLAYERS.
FINAL MASTER’S THESIS
Supervisor: Assoc. Prof. PhD. Sandrija Capkauskiene
Scientific adviser: Prof.Doc. Dr. Vilma Juodžbalienė
Final thesis has been prepared by ____1___ students
KAUNAS 2016
1
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TABLE OF CONTENTS
ABSTRACT .......................................................................................................................................... 5
SANTRAUKA ....................................................................................................................................... 7
INTRODUCTION ................................................................................................................................. 9
1. LITERATURE REVIEW ................................................................................................................ 11
1.1 Hamstring Muscle Injuries ............................................................................................................ 11
1.2 Incidence & Risk factors Hamstring muscle injuries in Soccer .................................................... 12
1.3 Flexibility of the Hamstring muscle .............................................................................................. 15
1.4 Application of Stretching on Hamstring muscle ........................................................................... 16
1.5 Types of Stretching: ....................................................................................................................... 18
1. 5.1-Static Stretching ....................................................................................................................................... 19
1.5.2-Dynamic Stretching .................................................................................................................................. 19
1.5.3 Ballistic Stretching .................................................................................................................................... 20
1.5.4 Muscle Energy Techniques ....................................................................................................................... 21
1.5.5 Proprioceptive Neuromuscular Facilitation Stretching ............................................................................. 22
1.6 Vertical Jump Performance (VJP) ................................................................................................. 26
1.7 Measuring Hamstring Flexibility................................................................................................... 27
2. METHODS AND METHODOLOGY ............................................................................................ 32
2.1. Research objects ........................................................................................................................... 32
2.2. Participants ................................................................................................................................... 32
2.3 Methods ......................................................................................................................................... 33
3. RESULTS ........................................................................................................................................ 39
4. DISCUSSION .................................................................................................................................. 45
CONCLUSIONS ................................................................................................................................. 48
SUGGESTIONS .................................................................................................................................. 49
ACKNOWLEDGMENT ..................................................................................................................... 50
REFERENCE ...................................................................................................................................... 51
ANNEXURE ....................................................................................................................................... 61
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ABBREVIATION:
AKE-Active Knee Extension
CNS-Central Nervous System
CRAC-Contract Relax Agonist Contract
GTOs-Golgi Tendon Organs
HMIs -Hamstring muscle injuries
METs-Muscle Energy Techniques
PIR-Post Isometric Relaxation
PNF-Proprioceptive Neuromuscular Facilitation
ROM-Range of Motion
SLR-Straight Leg Raise
SRT-Sit and Reach Test
VHT-Vertical Height Test
VJP-Vertical Jump Performance
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EFFECT’S OF DIFFERENT MUSCLE STRETCHING TECHNIQUES ON
HAMSTRING MUSCLE FLEXIBILITY IN AMATEUR SOCCER
PLAYERS.
ABSTRACT
Keyword: Hamstring, flexibility, stretching, Muscle energy techniques, PNF, soccer, muscle force.
Research object: Effects of Muscle energy technique and Proprioceptive neuromuscular facilitation
(PNF) stretching on hamstring muscle flexibility in amateur soccer players.
Research problem: Hamstring injuries are one of the most pressing problems in sports. It’s most
common among the soccer players.
Study subjects: Amateur male soccer players U- 21 team from Lithuania.
Aim: To investigate and compare the effects of Muscle energy techniques and Proprioceptive
neuromuscular facilitation (PNF) stretching on hamstring muscle.
Hypothesis: we presume that both Muscle energy technique and Proprioceptive neuromuscular
facilitation stretching techniques will have equal effects in improving hamstring muscle flexibility.
Objectives of the research:
1. To evaluate and compare the effects of muscle energy techniques and Proprioceptive
neuromuscular facilitation (PNF) stretching on hamstring muscle flexibility
2. To evaluate and compare the effects of muscle energy techniques and Proprioceptive
neuromuscular facilitation (PNF) stretching on Muscle force by measuring vertical jump
height.
Study methods:
30 amateur male soccer players randomly grouped into three groups. First group(A) was
given with Muscle energy techniques(post isometric relaxation) ,Second group (B) were given
Proprioceptive neuromuscular facilitation (contact relax agonist contract) and the third group was
controlled group(C) no stretching given. All three group were given 5 minutes warm-up cycling, the
Muscle energy technique (METs) group included 5-minute warm-up followed by a Muscle energy
technique (METs) Techniques routine for 6 minutes and the proprioceptive neuromuscular facilitation
(PNF) group included 5-minute warmup followed by a Proprioceptive neuromuscular facilitation
(PNF) stretching routine for 6 minutes. The subjects performed all the routines on three separate days.
All the subjects performed were measured and 3 countermovement vertical jump on the force
platform before stretching, immediately after stretching, and after 10-minute.
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Result:
The data analysis showed a no significant difference (p < 0.569) in Hamstring flexibility
following both Muscle energy techniques and Proprioceptive neuromuscular facilitation stretching
between and significant within groups for both the variables. The results of this study suggest that
both Muscle energy techniques and Proprioceptive neuromuscular facilitation stretching are equal
effects in improving Hamstring flexibility and reducing muscle force.
Conclusion:
1. The current study found that there is no significant difference in Hamstring muscle
flexibility following Muscle energy techniques and Proprioceptive neuromuscular
facilitation types of stretching. Both
Muscle energy techniques and Proprioceptive
neuromuscular facilitation types of stretching are equally
effective
on hamstring
flexibility .
2. The current study found a no significant difference in muscle force following Muscle
energy techniques and Proprioceptive neuromuscular facilitation stretching between the
groups. Both muscle energy techniques and Proprioceptive neuromuscular facilitation
stretching are equally effective in reducing the muscle performance in vertical jump height.
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SKIRTINGŲ RAUMENŲ TEMPIMO TECHNIKŲ ĮTAKA, FUTBOLO
MĖGĖJŲ, PUSGYSLINIO RAUMENS LANKSTUMUI
SANTRAUKA
Raktiniai žodžiai: pusgyslinis raumuo, lankstumas, tempimas, jėga, raumenų eneregijos technika,
proprioreceptorinių nervų ir raumenų atpalaidavimas, raumenų jėga.
Tyrimo objektas: skirtingų raumenų tempimo technikų įtaka futbolo megėjų pusgyslinio raumens
lankstumui.
Tyrimo problema: pusgyslinio raumens traumos yra viena iš staigiausių problemų sporte. Tai
labiausiai būdinga futbolo žaidėjams
Tyrimo tikslas: ištirti ir palyginti raumenų energijos ir proprioreceptorinių nervų bei raumenų
atpalaidavimo technikos poveikį pusgyslinio raumens tempimui.
Hipotezė: darome prielaidą, kad abu ramenų tempimo metodai turės lygios poveikį pusgyslinio
raumens lankstumui.
Tyrimo uždaviniai:
1. Ištirti ir palyginti raumenų energijos, proprioreceptorinių nervų bei raumenų atpalaidavimo
technikos poveikį pusgyslinio raumens tempimui.
2. Ištirti ir palyginti raumenų energijos, proprioreceptorinių nervų bei raumenų atpalaidavimo
technikos poveikį raumenų jėgai, matuojant vertikalų šuolį į aukštį.
Tyrimo metodai:
30 futbolo megėjų vyrų atsitiktinai suskirstyti į tris grupes. Pirmajai (A) grupei buvo taikoma
raumenų energijos technika (post-izometrinė relaksacija). Antrai grupei (B) buvo taikyta
proprioreceptorinių nervų ir raumenų relaksacija (siekiant atpalaiduoti agonisto veiklą) ir trečiajai (C)
kontrolinei grupei nebuvo taikomas tempimas. Visoms trims grupėms buvo taikomas 5 minučių
apšilimas, raumenų energijos technikos grupei pridėtas 5 minučių apšilimas su reaumenų energijos
technika. Antrai grupei taikytas 6 minučių ir proprioreceptorinių nervų bei raumenų atpalaidavimo 5
minučių apšilimas. Visų tiriamųjų matavimai buvo atliekami trijų dienų laikotarpyje. Trimis
bandymais buvo matuojamas visų tiriamųjų vertikalus šuolis į aukštį ant jėgos platformos prieš
tempimą, iš karto po tempimo, po 10 minučių.
Rezultatai:
Duomenų analizė parodė, kad nėra statistiškai reikšmingo skirtumo tarp pusgyslinio raumens
lankstumo ir abiejų raumenų energijos technikų bei proprioreceptorinių nervų bei raumenų
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atpalaidavimo tempimo technikos ir abiejų grupių kintamųjų. Šio tyrimo rezultatai rodo, kad raumenų
energijos technikos ir proprioreceptorinių nervų bei raumenų atpalaidavimo tempimo technikos daro
vienodą įtaką gerinant pusgyslinio raumens lankstumą ir didinant raumens jėgą.
Išvados:
1. Dabartinio tyrimo metu nustatyta, kad nėra statistiškai reikšmingo skirtumo taikant raumenų
energijos technikos ir proprioreceptorinių nervų bei raumenų
atpalaidavimo tempimo
technikas pusgyslinio raumens lankstumui. Šios abi tempimo technikos daro vienodą įtaką
pusgyslinio raumens lankstumui.
2. Dabartinio tyrimo metu nustatyta, kad nėra statistiškai reikšmingo skirtumo vertinant raumenų
jėgą tarp grupių, taikant raumenų energijos technikos ir proprioreceptorinių nervų bei
raumenų
atpalaidavimo tempimo technikas pusgyslinio raumens lankstumui. Šios abi
tempimo technikos daro vienodą įtaką mažinant raumens darbą atliekant vertikalų šuolį į
aukštį.
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INTRODUCTION
Athletes perform warm-up before any physical activity in the belief that it enhances
performance and reduces the risk of injury (Young & Elliott, 2001). There are lots of other benefits
that can be achieved through warm-up, for example, increasing range of motion, delaying muscle
fatigue, reducing and preventing delayed onset of muscle soreness, improving maximal muscle
contraction, increasing the muscle and connective tissue temperature (Alter, 2004). Among all the
different types of warm-ups, stretching was one of the most commonly followed warm-up routine
(Shrier, 2004). However, there are several conflicting opinions regarding the effects of stretching; for
example stretching reduces performance (Little & Williams, 2006), reduces force production (Shrier,
2004), and results in decreased power production (Manoel et al., 2008). In contrast to the above
comments there has also been research that stated that stretching improves range of motion (Alter,
2004) and increase force and power production (Nelson et al., 2001). In spite of these contrasting
comments most athletes do include stretching in their warm-ups (Shrier, 2004). The athletes are now
aware of these issues and are focusing on different types of stretching, thereby trying to minimize its
detrimental effect on sporting performance. This encouraged several researchers to find the effects of
different types of stretching on sporting performance.
Most of the research on static stretching stated that it was detrimental to muscular
performance (McMillan et al.,2006; Power et al., 2004; Wallmann et al., 2005; Church et al., 2001;
Bradley et al., 2007), but there are only few studies which investigated the effects of PNF and
dynamic stretching on athletic performance. Moreover, these researches showed conflicting findings.
For example, Young and Elliott et al., (2001) found increased force production and minimal decrease
in jump height during vertical jump following proprioceptive neuromuscular facilitation (PNF)
stretching. In contrast, Church et al., (2001) found that proprioceptive neuromuscular facilitation
(PNF) stretching resulted in decreased vertical jump height. Similarly, Yuktasir et al., 2007 stated
that proprioceptive neuromuscular facilitation (PNF) stretching had no effect on force and power
production, whereas Christensen and Nordstrom, (2008) and Marek et al., 2005 found that
proprioceptive neuromuscular facilitation (PNF) stretching decreased power and agility performance.
Similarly for dynamic stretching, Stewart et al., 2003 found an increase in jump height by 7%
following dynamic stretching. In contrast, Christensen &Nordstrom (2008) found no difference in
jump height following dynamic stretching. Fletcher et al., 2004 stated that dynamic stretching
improved sprinting performance, whereas Yuktasir, 2007 stated that dynamic stretching had no
significant effect on jump performance.
While muscle energy techniques are generally used by practitioners and other manual
therapists, there is only few studies supporting and validating its use, as well as fewer evidence to
substantiate the theories used to elaborate the effects of muscle energy techniques. Many researchers
9
have examined the effect of contract-relax techniques (similar to MET) on hamstring flexibility, and
found that these methods shown improved muscle flexibility.(Gribble, 1999; Handel et al., 1997)
identified significant improvements seen in hamstring flexibility along with an increase in passive
torque after a contract-relax exercise program. Wallin et al., claimed that contract-relax techniques
were more effective than ballistic stretching for improving muscle flexibility over a 30-day period,
whereas other researchers, however, have reported no differences between the two techniques,
Madeleine & Fryer (2008) found that both Chaitow and Greenman muscle energy techniques
improves flexibility immediately after the stretching, however no big variation between the two
approaches. M.Waseem et al., 2009 claimed that Muscle Energy Techniques Significantly increasing
the hamstring flexibility. However there is no previous study that compares both proprioceptive
neuromuscular facilitation (PNF) stretching and Muscle Energy techniques on Hamstring Flexibility.
Hypothesis
We presume that both Muscle energy technique and Proprioceptive neuromuscular facilitation
stretching techniques will have equal effects in improving hamstring muscle flexibility and reducing
muscle force.
Aim: To investigate and compare the effects of Muscle energy techniques and Proprioceptive
neuromuscular facilitation (PNF) stretching on hamstring muscle.
Objectives of the research
1.
To compare the effects of Muscle energy techniques and Proprioceptive
neuromuscular facilitation (PNF) stretching on hamstring muscle flexibility using
two different measurement tools i.e. Active knee extension and sit and reach test.
2.
To compare the effects of Muscle energy techniques and Proprioceptive
neuromuscular facilitation (PNF) stretching on muscle force using Vertical jump
Height measurement .
10
1. LITERATURE REVIEW
1.1 Hamstring Muscle Injuries
Muscle injuries are most common amongst the sport injuries and muscle injuries are said to be
one of the foremost prevalent time-loss injuries in sports and many of these are because of over-strain
or contusion (Jarvinen et al., 2005). The thigh region (lower-limb) is the very usual muscle site affects
in soccer (Ekstrand et al., 2011) and many other sports (Borowski, 2008). Hamstring muscle injuries
(HMIs) are the very common muscle injury in soccer (Ekstrand et al., 2011), and track and field
(Alonso, 2008). In Football, a professional player suffers 30% muscle injuries per season, 92% are
sited in lower limbs and 37% suffering hamstrings with a mean absence of 14.3 ± 14.9 days and a reinjury rate of 16% which may causes a player longer absence from a game (Hägglund et al.,
2012) .Drezner et al.,2003 stated that Hamstring muscle injuries have repeatedly founded as a very
common muscle injuries in sports like running and sprinting., as well as in Soccer (Askling &
Karlsson,2003)Talking about the common injuries in soccer game there has been many studies done
recently on many professional footballers. Ekstrand et al., 2011 stated that in football (soccer) muscle
injuries are very common injuries. The same said by studies done by Petersen et al., 2011; Woods et
al., (2004). A recent articles on male professional soccer players founded that in soccer injuries more
than 30% injuries occurs on muscle and cause about 1/3 of total injury absence (Waldén et al.,
2011).More than 90% of muscle injuries occurs in 4 major muscle clusters of the lower limbs:
hamstrings, quadriceps, gastrocnemius, and adductors (Ekstrand et al.,2011).Among these 4 muscle
groups, Hamstring Muscles reported to be very commonly affected in soccer with 37% injuries of all
injuries (Ekstrand et al., 2011)
Anatomical Structure of Hamstring Muscle
It is important to know about the knowledge of the particular anatomy of the muscle when we
discuss on and trying to understand the injuries. Hamstring muscle clusters are composed of 4
muscles situated in the posterior part of the thigh, the biceps femoris (long head), the biceps femoris
(short head), the semitendinosus (ST) and the semi-membranous(SM) (Miller, 2007). In general, these
4 muscles are branched to two clusters, the lateral hamstrings (biceps femoris long and short heads)
and the medial hamstrings (semi-tendinous and the semi-membranous) according to their locations on
the rear part of the thigh. The biceps femoris (long head), the semi-membranous and the semitendinous, are all two joint muscles (bi articular). These two joints muscles come across the hip, and
being connected to the the hip joint ischiac tuberosity (Batterman, 2011), and cross the knee, being
connected to the fibula and tibia, despite additional insertion sites have also been reported (Tubbs,
2006). These two joint (bi articular) muscles therefore cause both knee flexion and the hip extension.
The biceps femoris (short head) is a single-joint muscle and causes only knee flexion. Being a group
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Hamstring Muscle can be prepared by physical activities that involve either knee flexionor hip
extension. These two joint articular anatomy generallyimplies that the hamstring muscles are
loadedmaximum over two joints at the same time, as in tapering eccentrically at the level of hip and
knee whareas lengthened in end swing phase of sprinting (Chumanov et al., 2007; Dorn et al., 2012,)
Mechanism of Hamstring Injury
In eccentric contraction, once a force exerted on a muscle exceeds the force developed by a
muscle, work is completed on the stretching muscle and within the process the muscle absorbs energy.
The degree of energy that a muscle will absorb is believed to be associated with injury risk
(Garrett,1996; Mair et al.,1996; Magnusson et al.,2000). Hamstring strain injuries normally occur
close to musculo-tendinous junction (Proske, 2004) and generally while an individual is accelerating
or running (Verrall et al., 2003; Woods et al., 2004), specifically if there is a degree of forward
flexion (Verrall et al., 2003). Speculation exists regarding the precise point once hamstring strains
occur; few researchers dispute that starting stance is the serious (critical) point, whereas others
maintain that hamstrings are very biomechanically vulnerable to injury during terminal swing
(Heiderscheit et al., 2005 ;Chumanov et al., 2007; Chumanov et al., 2012). Such assumption has
normally been based on theoretical rationale (Stanton & Purdham, 1989) or analysis of symptomless
subjects (Orchard & Seward, 2002); these techniques are unable to definitely establish when in the
sprinting cycle the hamstrings fail.
1.2 Incidence & Risk factors Hamstring muscle injuries in Soccer
There is no second point of view that Soccer is one of the very leading and most popular
sports all over the world, with more than 300m participants(FIFA 2014) Unfortunately, studies on
sports injuries shows that high injury incidence rates for soccer games, particularly with male soccer
players
being
leads
over
the
counterparts
to
injury.(Dvorak
et
al.,2000;Wong
et
al.,2005;Ekstrand ,2011;van Beijsterveldt et al.,2014) Incidence rates of injuries are around 20.4% to
36.9%injuries/1000 match hrs., and 2.4%to 3.9%injuries/1000 training hrs. have been noted in male
soccer(Kordi et al.,2011;van Beijsterveldt et al.,2014).It’s said that Hamstring Muscle are quite usual
among the football injuries(Ekstrand,2011; van Beijsterveldt ,2012).They recital for 37% of all soccer
muscle injuries, requiring extensive therapy and prolonged rehabilitation duration (Hägglund et
al.,2009;Ekstrand ,2011;van Beijsterveldt ,2012). Repetition rates for hamstring injuries stays high
(12%-33%) despite preventive measures (Hägglund et al., 2009; Heiderscheit et al., 2010; Woods et
al., 2004).
Numerous epidemiological studies shown that the amount of injuries while the match is about
4–6 times over that in training session. Over 65% of soccer injuries are termed as acute 25% moderate
and 10%chronic (Rahnama, 2011). In men’s, the most rate of sports injuries is in soccer (Sreekaarini
12
et al., 2014).It is very vital to grasp the individual risk factors as a base for developing protective
measures. Hazards factors are usually divided into two key groups: internal and external. Moreover, it
would be more comparative to make a split between modifiable and non-modifiable (Bahr, HolmeI,
2003). Numbers of possible risk factors have been recommended for hamstring strains. But only some
areevidence based recommendation, and some are highly based on theoretical records. The very usual
non-modifiable factors in the studies are ageing (Woods et al.,2004; Verall et al.,2001; Arnason.A et
al.,2004) ethnic origin.(Woods et al., 2004)and in modifiable factors are flexibilities and imbalance
of muscular strength with a low hamstring to quadriceps ratio (H:Q ratio)(Croisier et
al.,2002;Drezner,2003,) muscle fatigue(Woods et al.,2004)insufficient warm up and hamstring
tightness(Garrett, 1996;Kujala et al.,1998;Drezner 2003;Hartig ,1999;Witvrouw, 2003), Based on
theory model proposed by Worrell et al., 1994 suggested that a combination of defects (strength,
flexibility, warm up, fatigue) will increase the probability of hamstring strain. As briefed by (Devlin,
2000) there might be a threshold at where number of risk factors causes damage. Players who return
to play before the full recovery are at risk of recurrent and have more probability of chronic
injury(Dzener, 2003) A recent prospective cohort study by Witvrouw et al.,2003 indicates that soccer
players with exaggerated tightness of the hamstring muscles have a considerably higher risk of a
subsequent musculoskeletal lesion.
In Soccer, mostly hamstring strains happens when players are running or sprinting (Arnason,
1996; Woods et al., 2004). The bicep femoris of all the three Hamstring Muscles has the much
muscle- tendon length and is stretched the more throughout sprinting, that’s why it is being the most
repeatedly injured. Soccer also needs fast and sudden change of speed and direction and this can also
be a reason to boost the rate of bicep femoris injuries as these muscle plays a vital role as lateral
rotators at the time when the knee is half-flexed and the hip is extended. While the first half of the
stance phase, the hamstrings muscle remain brisk through a concentric contraction, opposing knee
extension distally while extending hip. The hamstrings act to slow down knee extension distally while
in another end helping hip extension in the latter half of swing phase while sprinting. During the
eccentric contraction of the hamstrings muscle at the lateral starge of swing phase, the muscle
approches maximal length, and it is said just before the heel strike the most possibility of the muscle
strain injury is high(Ramahi , 2013). Most studies recommend that hamstring strains occur during the
latter part of the swing phase when the hamstrings are working to decelerate knee extension-that is,
the muscle develops tension while lengthening. This means that the hamstrings must change from
functioning eccentrically, to decelerate knee extension in the late swing, to concentrically, becoming
an active extensor of the hip joint.(Woods et al.,2004; Clanton , 1998) It has been found that it is
during this rapid change from eccentric to concentric function that the muscle is most vulnerable to
injury(Verrall , 2001) The reason of hamstring injuries have been credited to a not enough strength in
13
the hamstrings, reduced hamstring flexibility as well as imbalance or poor strength between the lower
extremities in hamstring and quadriceps muscle.
Internal Risk Factors;
-
Age
Gender
Body Composition
Health(including
previous
injury
history)
- Physical
Fitness(including
Flexibility)
- Anatomical Factors
- Skil lLevel
PREDISPOSED
ATHLETE
SUSCEPTIBLE
ATHLETE
External Risk Factors;
Inciting Event;
-
-
Other players
Protective Equipment
Sports Equipment
Environmental Factors
Fatigue
INJURY
Joint Motion
Playing Situation
Training Programme
Match Schedule
Figure 1. Showed the Conceptual model of injury pre-disposition (modified from Meeuwisse, 1994)
Flexibility is included as an intrinsic risk factor in most conceptual models of injury such as
the one shown in Figure-1.(Meeuwisse,1994) and is considered a primary etiological factor associated
with musculo-tendinous strain injuries(Kroll & Raya, 1997; Kujala et al., 1997; Bennell et al.,1999
;Devlin,2000;Hrysomallis, 2009 ;Engebretsen et al., 2010; Beijsterveldt et al.,2012).Eleven
prospective cohort studies examining the relationship between flexibility and hamstring injury have
been conducted. These studies used amateur (Bennell et al.,1998; Gabbe et al .,2005; Yeung et
al.,2009; Engebretsen et al.,2010) and professional participants (Orchard et al.,1997; Witvrouw
et
al.,2003; Arnason et al.,2004; Gabbe et al.,2006; Bradley &Portas,2007; Arnason et al.,2008;
Henderson et al.,2010) and measurements were either ROM( Witvrouw et al.,2003; Arnason et
al.,2004; Gabbe et al.,2005; Gabbe et al.,2006 ; Bradley &Portas,2007; Engebretsen et al.,2010) or sit
and reach test scores (Orchard et al.,1997). Eight of these studies demonstrated no significant
association between flexibility and hamstring injury incidence via logistic regression analysis (Bennell
et al.,1998; Arnason et al.,2004; Gabbe et al.,2005; Gabbe et al.,2006; Arnason et al.,2008; Yeung et
al.,2009; Engebretsen et al.,2010). Three studies involving professional footballers reported lower
ROM of hip and knee flexors in players who subsequently sustained muscles train injury (Witvrouw
et al., 2003; Bradley & Portas, 2007; Henderson et al., 2010). The disparity in findings may be
14
associated with the type of analysis applied and the inclusion or exclusion of participants with
previous injury. Consistently it must be remembered that risk factors only lead to injury susceptibility
and to provide a greater understanding of patterns leading up to an injury situation, the inciting event
should also be described(Bahr, 2003).
Decreased flexibility is increasing the hazards for injuries and this includes the hamstring
(Jönhagen.S, 2005) .Unlike other features ofmotor activity, there is no intention of developing
maximum output when it comes to flexibility. The athlete’s level of flexibility should be optimum or
allow for a slight excess in ROM when performing an exercise (Makaruk & Makaruk, 2009). It
remains unclear if reduced hamstring flexibility is either cause or consequence of hamstring injury
because large number of
information about risk factors are composed retrospectively(Bahr R
2003).This studies will so put the focus on hamstring flexibilities and strecthing targeting developing
of hamstring force .
1.3 Flexibility of the Hamstring muscle
Muscle flexibility is known as the ability of a muscle to enlarge, allowing one joint or more
than one joint in movements to move through a range of motion (Marginson et al., 2003). Flexibility
is important to permit for the greatest efficiency of the musculoskeletal system (Buschbacher, 2002)
particularly for functional range of motion (Sexton & Chambers, 2006).Flexibility is considered as an
important element of regular biomechanical functioning in sport (Hopper et al., 2005). The studies
review reports a several associated advantage of flexibility which includes improved athletic
performance, lowering injury risk, hindrance or reduce of post-exercise soreness and improved coordination (Pope et al., 2000).
Flexibility training is said to be a key reason of injury prevention in athletes despite a lack of
strong potential scientific studies (Witvrouw & Mathieu, 2004). It is suggested that increased
flexibility can lower the chance of muscle strain injury because of higher capacity of the passive
components of the muscle-tendon group to absorb energy as a result of majorassent (Witvrouw, 2004).
Hamstring strains are very frequent athletic injury with a tendency to reaccure (Worrell, 1992).
Lack of flexibility has been said as a predisposing issue to hamstring strains (Jonhagen, 1994).
Therapist have usually considered flexibility training to be an associate element in the prevention and
rehabilitation of injuries, similarly as an approach of increasing one’s performance in daily activities
and sports. A potential study of 146 soccer players shown that 21% of players tends to hamstring
injuries, which these players had considerablydecreased hamstring flexibility before sustaining the
injury compared with non-affected players (Witvrouw, 2003).
One among the foremost effective ways of preventing the implications of muscle shortness is
stretching exercises or techniques (Kisner & Colby, 2002). Similar to the above, there are several
15
other researchers like (Bradley et al.,2007; Church et al.2001; Knudson et al., 2001; Evetovich et al.,
2003; Hoffman et al.,2000 )had contrasting opinions about the effects of stretching on Flexibility.
Therefore, this study attempts to find which stretching technique is more effective on Hamstring
muscle Flexibility.
1.4 Application of Stretching on Hamstring muscle
Stretching is said to be a movement applied by an external or internal force in order to
improve muscle flexibility or joint range of motion (Weerapong et al., 2004). Taylor et al., (1994)
showed that during stretching, the overlap between myosin and actin filaments within the sarcomere
decreased which resulted in muscle fibre elongation until maximum resting length. After reaching the
maximum resting length, a maintained stretching force acts upon the non-contractile elements such as
tendon, perimysium, epi-mysium and endo-mysium (Kolt & Snyder-Mackler, 2007). To understand
the concept and application of stretching, the physiological characteristic of compliance must first be
discussed.
Stretching is a type of physical activity in which a muscle or a cluster of muscles are put in a
lengthened state by positioning the joints in the inverse direction to the action of that objective muscle
or group of muscle action(Weerapong et al., 2004). Stretching is mostly used as a part of warm-up, or
as a warm up itself, before a game action (Fradkin et al., 2010; Marek et al., 2005; Tsolakis et
al.,2010;Witrouw,2004). Kisner et al., (2009) stated that, one of the very effective techniques of
preventing the incidence of muscle shortness is stretching exercises or techniques. As per Shrier
(2005), the conviction is that stretching will increase performance. Stretching has been explored for
its commitments in many areas of study: (a) to decrease the chance of muscle damage (Herbert &
Gabriel, 2002;Thacker et al., 2004;Shehab, &Gorenflo,2006; Small & McNaughton, 2008; McHugh
& Cosgrave, 2010), (b) to increase athletic performance (Papadopoulos et al ., 2005), (c) to anticipate
delayed onset of muscle soreness (Johansson, Lindstrom &Lindsrom, 1999) and (d) to improve the
range of motion (ROM) of the joint (Ryan, 2008).There are few research focused on improving the
flexibility through various training methods like heavy-resistance training, plyometric training,
maximal strength training, electrostimulation training, vibration therapy (Markovic, 2007).Most
therapists, however, still recommend and include stretching in their warm-up (Shrier, 2004), as it
improves flexibility, prevents injuries, and improves performance (Young & Behm, 2002).
Despite the statement made by Young & Behm (2002) that stretching prevents injuries and
improves performance, many researchers (Bradley et al., 2007; Unicket al., 2005; Church et al., 2001;
Nelson et al., 2001) stated that stretching prior to any sporting activity results in decreased muscle
strength, which may also lead to injuries. Liebesman and Cafarelli (1999) stated that joint stability is
compromised due to a sudden increase in joint mobility due to stretching and may predispose an
16
athlete to injury. In support of the above comments, Lally (1994) conducted a survey of 6,000
marathon runners and found that the injury rates were highly associated with athletes who included
stretching in their warm-up.
Following this Avela et al., (1999) measured the activity of the muscle spindles the following
stretching, and found that there was a significant decrease in muscle spindle activity and sensitivity to
force, which leads to decreased force production. Despite all this research showing a relationship
between injury and stretching, stretching before any physical activity is the most common practice
followed from amateurs to elite athletes (Holcomb, 2000; Church et al., 2001; Shrier, 2004). The
therapists are aware of this issue and have focused on types of stretching thereby trying to eliminate
detrimental effects of stretching. This has influenced some researchers to examine the effects of
various types of stretching on flexibility and the muscle performance. These days, a variety of
stretching techniques are performed to improve the flexibility of contractile and non-contractile
connective tissues. All these techniques have certain benefits, special features, and effects. Numerous
studies have found the effectiveness of these methods. Moreover, there are not many unanimous
consensuses on which stretching method is best and with well-defined parameters (Ballantyne, 2003,
Chan 2001).
Proprioceptors and Stretching
Located in muscles, tendons, and joints are sensory receptors, which are sensitive to tension
and pressure. These receptors are sending information from the muscles to Central Nervous System
(CNS), we should consider two important proprioceptors during stretching: Muscle spindles and
Golgi tendon organs (GTOs). Muscle spindles, located inside intra-fusal muscle fiberswhich run
parallel to extrafusal muscle fibers, monitor difference in muscle length. Meanwhile duringa rapid
stretching techniques, sensory neuron from the muscle spindle goes through a motor neuron in the
backbone of the spine. The motor neuron then makes a muscle action of the earlier stretched intrafusal
muscle fibers; this is the stretch reflex. Stimulation of the muscle spindle and the subsequent
activation of the stretch reflex should be avoided during stretching, as motion will be limited by the
reflexive muscle action. If the muscle spindles are not stimulated the muscle relaxes and allows
greater stretch. Because of the very slow movement during the static stretching, the stretch reflex is
not invoked. Rapid (ballistic and dynamic) stretching movement may stimulate the muscle spindles,
causing a stretch reflex.” (Baechle, & Earle, 2008)
Stretching Compliance: Compliance is defined as “the reciprocal of stiffness, and
mathematically it is equal to the length change that occurs in a tissue divided by the force applied to
achieve the change in length (Shrier,2007).According to this definition, the equation to
calculatecompliance can be expressed as follows:Compliance (c) = (Final length – Initial length).Applied Force -1 (Shrier, 2007).
17
Figure 2.Muscle spindle - stretching muscle activates sensory neuron; which sends an impulse to the spinal cord, where it
synapses with a motor neuron, causing the muscle to contract ( modified from Thomas r. Baechle; & Roger; 2008).
Mechanisms of Stretching
The mechanisms of stretching will be catagorised into discussions regarding the
biomechanical and neurological mechanisms affected during stretching followed by the effects of
immediate and long-term stretching. The mechanisms of stretching are detailed by its influence on
biomechanical properties of the musculo-tendinous unit MTU (ROM, creep, stress relaxation,
hysteresis, and thixotropy) and by neurological mechanisms (Hoffman reflex, autogenic and
reciprocal inhibition) (Cross, 1999; Weerapong,., 2004).
Benefits of Stretching:
Stretching has been shown to have numerous effects, including a reduction of injury risk,
enhanced athletic performance, and increased flexibility. Of these effects, an increase in flexibility is
the most commonly cited benefit with little debate regarding this specific effect of stretching (Feland
et al.,2001;Feland & Marin, (2004); Nordez et al., 2006; Reid, & McNair, (2004).Further, acute and
long-term stretching protocols produce varying results .Currently, there is little consensus regarding
the role of stretching on reducing the risk of muscle strain injuries (Shrier, 2007). However,
numerous studies suggest that there is a decreased risk of muscle strain injury associated with regular
stretching (Mason, et al., 2007; et al., 2004).
1.5 Types of Stretching
There is variety of stretching techniques aiming to improve the muscle flexibilities, but
generally, three starching techniques likes1) Static Stretching, 2) Dynamic stretching and 3) PreContraction Stretching are defined in the studies in an effort to improve flexibility after stretching.
18
The above-mentioned stretching techniques have it’s own advantages and disadvantages based on
effects, techniques which have been into many trails and studies.
Figure 3. Types of stretching-(Modified from Page,2012)
1. 5.1-Static Stretching
Static stretching is one of the most used techniques of stretching. This method of stretches is a
very effective for increasing range of motion; yet not as effective as Proprioceptive neuromuscular
facilitation (PNF) method, (Hatfield, 2011). In general there are 2 types of static stretching: (1) staticactive and (2) static-passive (Hatfield, 2011). In static-active stretches the person will slowly move to
assume a position, where is his or her extreme range of motion for the joint they want to stretch, and
they hold the position for 20 to 30 seconds; using their muscles without any assist. In static-passive
stretching the doer will remain in the assumed position with the help of an assistant. The assistant can
be partner or another apparatus such as a wall. Static stretching does not elicit a stretch reflex;
therefore the possibility of injury is less compare to that in ballistic stretching, and it allows greater
stretch. (Baechle & Earle, 2008).
1.5.2-Dynamic Stretching
Dynamic stretching refers to the movement of limbs in an well-organized pattern to improves
range of motion(ROM) ,Unlike static stretching movements do not exceed the individual’s limits of
range of motion within the joints being warmed up. The activities are sport/activity-specific (Carrand
et al., 2010). Some do not consider dynamic stretching a form of “stretching” but rather types of
warm-up activities. Dynamic stretching would still be considered a category of stretching techniques
because it purposefully elongates muscles being activated in exercise and it often replaces standard
19
acute static stretching. This technique is most widely used prior to exercise and has become more and
more prevalent in competitive athletic settings.
Cameron McGarr, exercise and fitness specialist encourages dynamic stretching because of its
ability to prepare the muscles better for exercise therefore, reducing the occurrence of injury. He says
that it should be done often because it learns the muscles to elongate while in movement improving
moving flexibility (McGarr, 2007). The concept of active flexibility is thought to be a factor in
decreasing the likelihood of injury. When an individual uses static stretching to prepare the muscles
for activity, the active flexibility has not been increased; only passive flexibility has been improved.
Dynamic stretching increases active flexibility and a person’s range of motion during exercise. It is
believed that static stretching alleviates muscle soreness but is it possible that muscle soreness could
be reduced through dynamic stretching. No direct research has been published to show that dynamic
stretching can be used to ease muscle soreness (Weerapong et al., 2004). However, it is observed that
dynamic stretching is more effective at stretching the muscle without damaging the ligaments while
static stretching often over-stretches the ligaments (Okragly, 2011). More research should be
conducted on chronic dynamic stretching and its impact on preventing musculoskeletal injuries and
relieving muscle soreness.
1.5.3 Ballistic Stretching
Ballistic stretching is a technique that involves a bouncing or bobbing motion during a stretch.
Instead of holding a position as in static stretching, the individual moves in and out of the stretch over
and over. It uses the momentum of the body part to force a greater range of moments in the joint.
Ballistic stretching promotes the stretch reflex reaction to the rapid lengthening of the muscle and has
been contraindicated in many textbooks (Morán & Arechabala, 2009). The Oxford Dictionary of
Sports Science and Medicine deems it a potentially injurious type of stretching, as ballistic stretching
increases the risk of muscle tears. In addition, Kent, 2006 reports that the risk of tissue damage
increases because the rapid, bouncing motion may carry the joints beyond their maximum range of
motion (ROM). Unlike dynamic stretching, ballistic stretching is erratic and uncontrolled and is rarely
recommended for the use of the general population (Blahnik, 2013). Despite the negative connotation
of ballistic stretching, it has been shown to improve flexibility in some cases (Mahieu et al., 2007). In
addition, one particular study revealed that ballistic induced significantly less muscle soreness than
static stretching (Smith et al., 1993). Several other studies have also investigated ballistic stretching
and its effects on performance. Ballistic stretching has also been shown to have no significant effect
on performance. A study investigating vertical jump after ballistic stretching showed no significant
difference in vertical jump height from not stretching (Jaggers et al., 2008).
20
1.5.4 Muscle Energy Techniques
Muscle energy technique is a manual technique developed by osteopaths which is used in lots
of different manual therapy by many manual therapy technicians (Ballantyne, 2003). Such approach
which targets the soft tissues has been termed as Muscle energy technique and this is also referred as
active muscular relaxation technique.
Effects of Muscle energy Techniques
Muscle energy techniques one amongst the most effective for a wide range of purposes which
includes lengthening shortened muscles and improving the range of motion (Ballantyne, 2003;Leon,
2000;Madeleine,2008).Muscle Energy Technique (MET) is one of few Manual technique which
includes specific contraction of a muscle, and is claimed to extend muscle flexiblity and joint motion
(Chaitow 1996). Muscle Energy Technique (MET) deals with both the soft tissue and articular
component of somatic dysfunction, and is mostly suggested by authors of manual therapy (Chaitow
1996). These kinds of techniques are a part of the evolution from quite forceful techniques such as
maximum velocity low amplitude thrusts, towards gentler techniques (Chaitow 1996). Numerous
studies have shown that both static stretching and isometric stretching such as MET are most effective
in increasing muscle flexibility, however there are different results as to the best effective technique
(Magnusson et al., 1996; Ballantyne et al., 2003; Gribble et al., 1999). Furthermore, few more authors
of MET have also suggested different methods of application of the technique, with some variation in
the force and duration of the stretch component and even in the direction of the isometric contraction
(Chaitow, 1996). Consequently, in addition studies into which techniques are the very effective to
assist manual therapists to providing the most effective treatments. Muscle energy techniques differs
from static stretching since it involves isometric contraction of the muscle when stretch from the
patient towards the resistance of the therapist in additional to other stretching. Once its applied for the
finding of improving muscle flexibility, there are resemblance between muscle energy techniques and
isometric techniques, like as contract relax (CR) and Proprioceptive neuromuscular facilitation
techniques executed in some other manual therapy disciplines.
Within the field of osteopathy, many other authors have suggested lots of ways applying
muscle energy techniques (MET), by altering the force, timing of contraction, angles of isometric
contraction and distance of post-contraction stretch (Bandy, 1998). Moreover, there has been not
numerous concerning investigation of the most effective application of Muscle energy techniques, or
has there been a study into the effectiveness of the Chaitow technique for the application of muscle
energy techniques (MET) to improve hamstring muscle flexibility. Chaitow , (1996) suggested
passive stretching of the hamstring muscles to a sense of tension, followed by an active, moderate
force isometric contraction of the hamstrings against the therapist resistance, and then an volunteer
contraction of the quadriceps muscles by the subject to reach increased range of motion, and last 30
21
seconds of passive stretching. In distinction, few other authors of Muscle energy techniques studies
suggest more soft contraction forces, exceptional to the agonist (quadriceps) contraction, and a fewer
duration of passive stretch (Greenman,1996). Shadmehr et al., 2009 stated both passive stretch and
muscle energy technique treatment methods were useful of increasing the shortness of hamstring
muscles.
1.5.5 Proprioceptive Neuromuscular Facilitation Stretching
Proprioceptive neuromuscular facilitation (PNF) stretching techniques are normally utilized in
the athletic and Hospital environments tore activate each active and passive range of motion with a
view to optimising motor performance and rehabilitation. Proprioceptive neuromuscular facilitation
(PNF) is a stretching used to improve ROM and flexibility. Proprioceptive neuromuscular facilitation
(PNF) technique to improve flexibility can be divided into 3 basic phases. First, the muscle is
lengthened in a stretch either actively or passively. Subject then preforms an isometric contraction
with the muscle that was just lengthened. Lastly, the subject actively or passively stretches the muscle
into further ROM. Proprioceptive neuromuscular facilitation (PNF) improves ROM by improving the
length of the muscle and by improving neuromuscular capability.
In a contract-relax-antagonist-contract (CRAC) stretch, the antagonists are first passively
stretched, which is followed by 6s to 11s or 15s isometric contractions and then followed by an
immediate 6s to 15s concentric contractions of the agonists. A 20s rest is needed between repetitions
(Hall & Brody, 1999). Previous studies which used the hamstrings as the antagonist muscle began the
CRAC sequence with a slow passive straight leg raising to the point of mild discomfort (Worrell et
al.,1994) or stretch sensation (Ryan et al.,2010) as determined by the participant. The durations of
isometric hamstring (antagonist) contraction during contract-relax-antagonist-contract (CRAC) in
these studies ranged from 5 s (Worrell et al., 1994) to 7 s (Ryan et al., 2010). While the rest duration
was not explicitly specified, it was inferred that Ryan et al (Ryan et al., 2010) used an immediate
transition to concentric quadriceps (agonist) contraction after the isometric hamstring (antagonist)
contraction. In contrast, Worrell et al., 1994, specified that the limb was maintained in the position of
stretch for a 5srest period after the isometric hamstring (antagonist) contraction. The duration of
quadriceps (agonist) contraction ranged from 4 s (Ryan et al., 2010) to 5 s (Worrell et al., 1994),
which was not within the duration range suggested previously (Hall & Brody, 1999). In addition,
Ryan et al., 2010 used a concentric quadriceps contraction, while Worrell et al., 1994 asked
participants to perform a maximal isometric quadriceps contraction, further demonstrating the
differences in documented techniques of CRAC stretching. There is No previous studies have
provided conclusive evidence of an optimal rest period between repetitions of the CRAC stretch
22
technique. However, previous studies have suggested rest periods between stretch repetitions of 10 s
to 20 s (Marek et al., 2005; Ryan et al., 2010).
Effects of Proprioceptive neuromuscular facilitation (PNF)
Proprioceptive neuromuscular facilitation stretching is listed in the reviews as the very
effective stretching methods when the aim is to improve passive range of motion (Sharman et al.,
2006). Proprioceptive Neuromuscular Facilitation (PNF) is a stretching technique used to increase
muscle elasticity and has been shown to possess a good effect on active and passive range of motions
(Funk et al., 2003). Latest studies has been targeted on the effectuality of the intervention on few
outcome measures, like passive range of motion (PROM), active range of motion (AROM), and
strength of the muscle. In clinical point of view, Proprioceptive neuromuscular facilitation (PNF) is
already used by teqhnicians to revive the functional range of motion (ROM) and improved strength in
patients who have sustained soft tissue injuries or underwent invasive surgeries. Funk et al., 2003 has
proven that proprioceptive neuromuscular facilitation (PNF) techniques also improve Range of
Motion (ROM). Two techniques are seen in the literature more frequently than others, the contractrelax method (CR) and the contract-relax-antagonist-contract method (CRAC) of Proprioceptive
neuromuscular facilitation (PNF). Likewise static stretching, modified hold-relax stretching is
currently utilized in many kind of manual therapy professions. These kindof exercises are modeled to
reinforce the neuromuscular response of the proprioceptors. Its been found to be very effective in
many conditions, such as in improving the length of reduced muscle, strengthening weak muscles,
improving lymphatic or venous return to aid the draining of fluid, and improving the joint range of
motion (ROM) of a limited joint (Ballantyne ,2003).
Talking about the importance of hamstring flexibility normally and athletic population,
retaining the flexibility of hamstring muscle is of foremost importance for health care technicians and
to realize this effect must grasp the very effective and best technique to improve hamstring flexibility.
Several research estalished Proprioceptive neuromuscular facilitation methods more very effective
than all other traditional stretching exercises for improving range of motion or improving muscle
flexibility. Marked improvement have been seen in the hamstring flexibility once Proprioceptive
neuromuscular facilitation stretching techniques are incorporated when compared to ballistic stretch,
static stretch or slow stretch(Surburg, 1997).
Funk et al 2003 stated Proprioceptive neuromuscular facilitation (PNF) stretching has shown
to improve range of motion in untrained as well as trained sportsman. He also stated that effects can
be last more or less than 90 mins after the completion of strectching.(Funk et al., 2003) Many
scientisthave examined the impact of contract-relax techniques (like as to modified hold-relax
stretching) on hamstring flexibility and said that these techniques produced improvement in muscle
flexibility (Gribble,1999;Handel, 1997). Handel et al 1997 stated marked improvement in hamstring
23
flexibility along with an improved in passive torque of muscle once a contract-relax exercise
performed. Relatedly, Wallin et al. Stated that the contract-relax technique was much effective
compare to ballistic stretching for increasing muscle flexibility over a 30-day period, whereas few
other researchers have stated no remarked difference between the these 2 techniques(Gribble,
1999;Handel, 1997).
Reviews and the studies in earlier which compared ballistic, static and proprioceptive
neuromuscular facilitation stretching techniques have proven that proprioceptive neuromuscular
facilitation was the most effective form of stretching (Funk et al., 2003; Sharman et al., 2006).
However, there are many variations of proprioceptive neuromuscular facilitation stretching protocols
.For example, earlier studies and reviews have reported varying agonist isometric contraction times
ranging from 3 s to 15 s (Feland et al.,2004;Ferber et al., 2002;Schuback et al., 2004;Sharman et
al.,2006,Spernoga et al.,2001). There is no compromise among studies regarding the specific duration
of fundamental components of proprioceptive neuromuscular facilitation (CRAC) stretches, which
include the durations of initial passive stretch, maximal isometric contraction, antagonist contraction,
rest between isometric and antagonist contractions, rest between isometric contraction and passive
stretch and rest between repetitions. Further, the total dose of stretching also determines cumulative
stretch impact. The dosage of stretch may be measured by total stretch duration; number of stretches
per session; amount of sessions per day or week and the course of time over which the protocol was
conducted. As a result of the lack of consensus regarding the optimal proprioceptive neuromuscular
facilitation duration and frequency of application, critical evaluation of proprioceptive neuromuscular
facilitation and its outcomes becomes difficult. A general review of the literature with the aim of
uncovering the impact of hamstring stretching techniques on range of motion finalised that it is
difficult to trustfully determine the foremost effective hamstring stretching techniques (Decoster,
2005). One more, Feland et al., 2001 stated that the hold-relax and static stretching had similar kind
of effects in increasing hamstring flexibility. Though, the improvement was much more for the
contract-relax proprioceptive neuromuscular facilitation group as related with the control and static
groups. Nagarwal et al., 2009 stated Proprioceptive neuromuscular facilitation Contract RelaxAntagonist Contract (CRAC) stretching method has shown more effective than Proprioceptive
neuromuscular facilitation (PNF) Hold-Relax stretching technique for increasing hamstring flexibility
but these both the methods are nearly same in their clinical effectiveness for increasing hamstring
flexibility and any of these methods can be utilized in theraputical practice for improving hamstring
flexibility. Feland et al., 2001 proved that contract-relax and static stretching both has same profits in
increasing flexibility. Similarly, Gribble et al., (1999) stated that static and hold-relax stretching both
the techniques are equally useful in increasing hamstring range of motion. Similiarly, Lim et al., 2014
founded that both the static and proprioceptive neuromuscular facilitation (PNF) stretching has
24
similiar effects on hamstring. Youdas et al., 2010 found that statistically significant increase seen in
hamstring muscle length using a one, 10s hold relax or 20s (Hold Relax-AC) cycle of modified
Proprioceptive neuromuscular facilitation stretching in normal healthy subjects with lesser hamstring
muscle length.
Few studies were found that investigate the differences between each proprioceptive
neuromuscular facilitation (PNF) technique. However, in 2012 a study was done Maddigan et al., to
compare assisted and unassisted proprioceptive neuromuscular facilitation (PNF) stretching.
Originally proprioceptive neuromuscular facilitation stretching required the assistance of a partner,
but in recent years straps have been implemented so that stretching may be completed alone. All three
methods of proprioceptive neuromuscular facilitation were completed with a partner and with a strap;
flexibility, reaction time, and movement time were measured pre-stretching and post stretching. No
significant difference was found between any of the assisted or unassisted Proprioceptive
neuromuscular facilitation techniques and ROM significantly increased for all methods. Reaction time
was not impacted and movement time decreased by 3.4% (Maddigan et al., 2012). Further research
would facilitate a greater understanding of how each Proprioceptive neuromuscular facilitation
technique can be used for maximum benefit. Several additional studies have been done that uncover
the effect of Proprioceptive neuromuscular facilitation on range of motion. Range of motion has been
found to considerably increase due to proprioceptive neuromuscular facilitation. A 4-day a week 6week Proprioceptive neuromuscular facilitation protocol elicited significant gains in range of motion,
but no statistically significant gains were observed in jump performance (Yuktasir, & Kaya, 2009).
Another study examined the plantar flexor range of motion (ROM) and the stiffness in the Achilles
tendon. The findings supported the notion that Proprioceptive neuromuscular facilitation (PNF)
stretching results in increased ankle dorsiflexion. But the increase in ROM could not be proven as a
result of decreased passive resistive torque or altered Achilles tendon stiffness. The author concluded
that the increased ROM is explained by an increase in stretch tolerance (Mahieu et al., 2009).
There are only a few researches which actually found, how long the effect of stretching lasts.
Moreover, these findings are important for a player to understand the optimal time for performing
stretching routines before any sporting events. Bradley et al., (2007) stated that the effects of
stretching lasted for 15 minutes, Similarly, DeWeijer et al., (2003) also found that the muscle length
gains after stretching declines within 15 minutes, whereas Fowles et al., (2000) found that the
isometric torque remained reduced by 9% even at 60 minutes after static stretching. However, a
limitation of Fowles et al., (2000) study could be that the measurements were taken using an
isokinetic machine, which does not represent the complexity of movement during a vertical jump. In
contrast, De Pino et al., 2000, found that the increased hamstring flexibility after stretching lasted
25
only for 3 minutes. Therefore, further research should focus on examining how long the achieved
effects does last.
1.6 Vertical Jump Performance (VJP)
Vertical jump is one of the most common activities in sports and VJP is considered to be one
of the most important criteria for athletic performance (Markovic, 2007). Hoffmann et al., 2000,
stated that the VJP test is more appropriate for basketball, since the sport involves constant jumping.
Similarly, Wisloff et al., 2004 stated that during a game of football an athlete covers about 8-12 km
and performs a jump every two minutes. This underpins the importance of vertical jump in sport
which involves constant jumping. Power is defined as the ability of the muscles to produce maximum
muscular contraction instantly in to a burst of movements (Thompson, 2007). The peak power is the
maximal power produced during the transition from eccentric to concentric contraction during the
vertical jump (Lara et al., 2006).
Wisloff et al., (2004) stated that an increase in power and force production in the muscles as a
result of stretching, strength training, resistance training, and plyo-metrics may increase VJP, which
in turn could improve sporting performance.
Similarly, Yamaguchi & Ishii (2005) stated that
stretching does improve VJP. In contrast to the above, Christensen & Nordstrom (2008) found that
stretching does not have any influence on VJP.
Similar to the above, there are several other
researchers like (Bradley et al., 2007; Church et al., 2001; Knudson et al., 2001; Evetovich et al., 2003;
Hoffman et al., 2000 had contrasting opinions about the effects of stretching on Vertical jump height
performance.
In contrast, another study that examined the acute effects of proprioceptive neuromuscular
facilitation (PNF) on explosiveforce, maximal contraction, and jumping performance found no
significant difference in performance due to the stretching (Elliot & Young, 2001). No significant
change was detected in twenty soccer players from a proprioceptive neuromuscular facilitation (PNF)
stretching routine on agility. The rationale behind the study was the notion that proprioceptive
neuromuscular facilitation stretching has been shown to produce an increase in musculotendinos unit
stiffness which is believed to be linked to an increased ability to store and release elastic energy. A
group of tennis players were studied to establish the effects of proprioceptive neuromuscular
facilitation on jump performance. No statistically significant change occurred to suggest that
Proprioceptive neuromuscular facilitation has a positive influence on power production (Carvalho et
al., 2009). Therefore, this study attempts to find whether stretching have any effect on Vertical jump
height performance.
26
Jump technique - countermovement jumps
Markovic et al., (2004) compared five different vertical jump techniques and two horizontal
jump techniques on 93 healthy physical education male students and concluded that
countermovement and squat jump techniques are the most reliable techniques to calculate the
maximal power output in the lower limb.
Similarly, Artega et al., (2000) stated that both
countermovement and squat jump are highly reliable. The reliability value for countermovement
jump was 93.7% to 95.7% and for squat jump 93.7% to 95%. Harman et al., 1996 found high testretest reliabilities for countermovement and squat jump (α = 0.94 and 0.99), while measuring the
jump height, peak power, and peak vertical force. But this study was conducted 20 years ago and the
sample size was fewer than 20. Moreover, they measured the variable with only one trial to prevent
fatigue.
Hunter and Marshall (2002) stated that countermovement jump produced a better result
(increase in jump height) than drop jump. Similarly, Linthrone (2001) suggested that an athlete can
jump higher in a countermovement jump than in a squat jump. This is clearly evident from their
force-displacement curves. They attributed this increase in jump height to stretch-shorten cycle; that
is, muscle action in a particular direction preceded by another movement in the opposite direction.
Bradley et al., (2007) stated that vertical jump involves multiple joint movements and requires a high
degree of coordination. Therefore, in this study a countermovement jump was used to determine the
effect of Vertical jump performance after stretching.
1.7 Measuring Hamstring Flexibility
Outcome Measures
Hamstring flexibility is most commonly measured by objective muscle length tests, including
the sit and reach test (Comble et al., 1996; Orchard et al., 2005; Youdas et al., 2008), straight leg raise
test (Henderson et al., 2010; Youdas et al., 2008), the passive knee extension test (Feland et al., 2001;
O’Hora et al., 2011) and the AKE test (DePino et al., 2000; Spernoga et al., 2001). There is no
confirmed evidence to suggest the superiority of one test over another (Orchard et al., 2005).
However, the advantages of the AKE test are the ability to isolate hamstring muscle length, and the
minimized amount of pelvic motion and neural stretch compared to the straight leg raise (Gajdosik et
al., 1993).In this particular study, Hamstring Flexibility is measured using Active knee extension
(AKE) test and Sit and Reach Test.
Numerous instruments might be used to quantify Muscle flexibility, which including the
flexo-meter (Mikesky et al., 2002). Inclinometery (Awan et al., 2002) and goniometery (DePino et
al., 2000; Funk et al., 2003). With regards to measures of hamstring flexibility, the reliability and
validity of both the measurement instrument and the testing procedure needs to be established.
27
Reliability in Goniometry refers to the repeatability of ROM measurements, if the application of an
instrument and test procedure will yield the same measurements consistently under the same
conditions (Gajdosik, 1987). Validity in goniometry refers to the degree of accuracy of the
measurement instrument and test procedure (Gajdosik, 1987). Goniometric measurements have
limitations because ROM results are expressed and limited to the degree units (°) of a circle which
would be valid if a fixed axis of motion was assumed .However, this is not true for human articular
structures which exhibit sliding, rotation and glide movements about axes of motion which are not
fixed (Kolt ,2007; Noedin & Frankel , 2001).
Straight-leg raise test (SLR). The principle measure of hamstring flexibility was mostly
decided by executing the Straight-leg raise test SLR test. This test was selected because of its wellknown acceptance as the principle measure of hamstring extensibility (Castro-Piñero et al., 2009;
Hartman & Looney, 2003; Kanbur et al., 2005). With the subject laid supine, the subject’s evaluated
leg was actively raised into hip flexion with the knee extended, slowly and progressively. To evaluate
the angle, the therapist placed an inclinometer (AcuAngle®, Japan) on the distal third of the tibia
anterior side, placing it at zero degrees in the starting position. The same therapist placed his hand
over the participant´s knee to keep the knee straight. Add to this, an auxiliary tester kept the contra
lateral leg straight into contact with the surface of the mat, avoiding pelvis external rotation and
preventing posterior pelvic tilt .The end point of the leg raise was determined by the tester's
perception of a firm resistance, and palpation by the auxiliary tester of the initiation of pelvis rotation.
The principle score of the hip flexion range of motion was the maximum angle recorded by the
inclinometer at the point of maximum hip flexion. (Sainz &Ayala, 2010).
The Inclinometery
Compared to the goniometer, the advantage of the inclinometer is that it responds to gravity
and there is no need to establish an axis of rotation during ROM measurements (Gajdosik , 1996).
Saur et al., 1996 founded that the reliability and validity of the inclinometer for measures of trunk
flexibility. Clapiset al., 2008 compared the reliability of the inclinometer and goniometer using hip
extension, to date no studies has compared instrument reliability using the AKE test as a measure of
hamstring flexibility.
Youdas et al., 2010 provided opposing evidence for the use of an inclinometer as a valid
measurement tool of hamstring flexibility during the sit and reach test. A pilot study showed high
intra-tester reliability of the inclinometer (ICC = 0.98; SEM = 1.9°) for hip joint angle measurement
during the sit and reach test. Hamstring flexibility was compared using hip flexion angle during the
sit and reach test (measured by an inclinometer) and passive SLR (measured by a goniometer). The
moderate correlation (r = 0.59) between passive SLR and hip flexion angle values during the sit and
reach test accounted for only 35% of the variability between the two measures of hamstring flexibility
28
(Youdas et al., 2010). Youdas et al., 2010 concluded that the measurement of hip joint angle using an
inclinometer during the sit and reach test was not a valid method of assessing hamstring muscle
length in individuals who could achieve long-sitting independently. However, the findings should be
interpreted with caution as the passive Straight-leg raise test procedure, participant positioning and
goniometer positioning during Straight-leg raise test was not explicitly described and a pilot study to
establish goniometer intra-tester reliability was not conducted.
Active Knee Extension (AKE)
Hamstring flexibility is generally measured by objective muscle length tests, Test containing
the sit and reach test (Comble et al., 1996; Rolls& George, 2004; Youdas et al., 2010 ), straight leg
raise test (Gajdosik , 2001; Henderson et al., 2010; Youdas et al., 2010 ), the passive knee extension
test (O’Hora et al., 2011)and the active knee extension(AKE) test (Spernoga et al., 2001).There is no
confirmed proof to propose the superiority of one test over another test(Rolls & George ,2004).
Though, the benefits of the Active knee test are the capacity to isolate hamstring muscle length, and
the minimized amount of pelvic motion and neural stretch compared to the straight leg raise
(Gajdosik, 2001).Additionally, compared to the SLR test, movements at the sacro-iliac joint, hip joint
and lumbar spine are controlled by stabilization during the AKE test (Rakos et al., 2001). The active
knee extension test position requires the participant to lie supine and the leg to be tested is positioned
at 90°/90° hip and knee flexion while the pelvis and opposite leg are stabilized using adjustable
straps. Sullivan et al., 1992 studied the effect of pelvic position on hamstring flexibility. A two way
ANOVA test that compared stretching technique (static and Proprioceptive neuromuscular
facilitation) and pelvic position (anterior and posterior tilt) found that anterior pelvic tilt notably
improves hamstring flexibility. Additionally, there were no significant differences between stretching
methods or for hamstring flexibility during the posterior pelvic tilt position, which suggests that
pelvic position was more influential for hamstring flexibility than stretching technique. Sullivan et al.,
1992 concluded that it was important to control pelvic motion while measuring the hamstring
flexibility. Rakos et al., 2001 investigated the inter-tester reliability of the active knee extension test.
The results of the pilot study established high intra-tester reliability (ICC = 0.99, 0.99 and 0.95) of
three examiners, for the AKE test as a measure of hamstring flexibility. While the results of the study
showed good inter-tester reliability (ICC = 0.79), the ankle position and hip rotation was poorly
controlled which may have influenced the results (Rakos et al., 2001).Gajdosik & Lusin, 1983,
investigated the intra-tester reliability of the AKE test performed bilaterally on 15 male participants.
The results showed high intra-tester reliability for test-retest measurements (ICC = 0.99 for both
lower limbs), which suggest that the AKE test was an objective and reliable test when conducted by
one examiner under controlled and standardized conditions .The difference in the AKE measurement
procedure used by Gajdosik & Lusin, 1983 compared to Rakos et al., 2001, was the use of slow
29
active knee flexion by the participant (self-applied) to the point at which myoclonus subsided. This
difference may have accounted for decreased active knee extension inter-tester reliability (ICC =
0.79) found previously, compared to the higher active knee extension intra-tester reliability found by
Gajdosik & Lusin (ICC= 0.99).
Gabbe et al., 2004, investigated the inter-tester and test-retest reliability of the AKE test as a
measure of hamstring flexibility together with other common lower extremity screening tests. Two
examiners performed each of the screening tests one week apart on 15 participants and the results
showed high inter-tester reliability (ICC= 0.93) and high test-retest reliability (ICC = 0.94 to 0.96) for
the active knee extension. However, Gabbe et al., (2004) did not control pelvic motion or stabilize the
contra lateral limb during the AKE test which may have influenced the ROM measurements as
suggested previously (Sullivan et al., 1992). Compared to the previous use of the point of myoclonus
as an indicative measure of the limit of active knee extension ROM (Rakos et al., 2001}.The results
of previous studies (Gabbe et al., 2004; Rakos et al., 2001; Sullivan et al., 1992; Webright et al.,
1997) suggested that differences in participant positioning and control of confounding factors
including pelvic, hip, sacroiliac, lumbar spine and neural tissue movement may influence reliability
of the AKE test as a measure of hamstring flexibility. The A active knee extension(AKE) test may
therefore provide a more realistic measure of hamstring flexibility, as active ROM that is induced by
active muscle contraction may simulate performance scenarios during sport more accurately.
Sit and Reach Test
Sit-and-reach tests are widely used as measurement tools for evaluating hamstring and lower
back flexibility (Baltaci et al., 2003; Holt et al., 1999). The sit and reach test and toe test have the
same testing procedure. They both have maximal trunk flexion with knee straight and ankle in 90 of
dorsiflexion but the only defense is the position of the test i.e. sitting and standing position
respectively. Most of the researchers always wanted to select a test that has the more validity and
reliability with the least equipment and preparation time (Hui & Yuen, 2000). There has been no
previous study that has 1) analyzed test retest reproducibility of Straight leg raising, sit and reach test
and toe test via contemporary statistical assessments, 2) determined the criterion-related validity of
Sit and Reach test for estimating hamstring flexibility measured through the passive straight leg raise
test (PSLR) and 3) used recreationally active young adults as sample. Several studies have analyzed
the reproducibility of SRT tests (the variability between repeated trials within a day) using traditional
measures of reliability, mainly though the calculation of intra-class correlation coefficient (ICC),
showing values ranging from r ¼ 0.91 to r ¼ 0.99 (Davis, Quinn et al., 2008; Hui et al., 1999; Hui &
Yuen, 2000; Jones et al., 1998; López et al., 2009; LópezMiñarro et al., 2008; Perret et al., 2001)
The most common understandings of sit and reach test results is that subjects with good scores
possess a higher degree of hamstring flexibility than those with less scores (ArreguiEraña & Martinez
30
de Haro, 2001; Bandy et al., 1998), while, the validity of the classic sit-and-reach test (CSR), and its
different modifications for estimating the hamstring muscle extensibility among young people has
been mostly questioned (Castro-Piñero et al., 2009; Garcia, 1995; Hartman & Looney, 2003; Kanbur
et al., 2005, López-Miñarro et al., 2008).
The sit and reach (SR) test is widely used to measure hamstring and low back flexibility
(Baumgartner, 1995). This test is present in most health related fitness test batteries because it is
believed that maintaining hamstring and low back flexibility may prevent acute and chronic
musculoskeletal injuries and low back problems, postural deviations, gait limitations, and risk of
falling. Numerous studies on the reliability and validity of sit and reach test(SR) protocols have been
mentioned, and a number have been proposed(Jones et al.,1998;Chung et al., 1999;Patterson et al.,
1996).The assumed validity of the sit and reach test is based on a inductive analysis of its provisions.
However, Jackson and Baker described a study that tested the relations between the sit and reach (SR)
test and criterion measures of hamstring muscle and low back flexibility in girls of aged around 13–
15. What they found in that study was validity coefficients of r = 0.64 between the sit and reach test
and a criterion measure for hamstring flexibility, and r = 0.28 when compared with a criterion
measure for low back flexibility. All sit and reach(SR) test procedures produce mild validity for
hamstring flexibility and poor validity for lower back flexibility(Jackson et al., 1998).The most
common belief when representing Sit and reach flexibility test results is that subjects with higher
scores holds a higher degree of trunk and hip flexibility than those with fewer scores(Bandy et al.,
1998). Previous research’s signifies that reliability estimates for the standard sit and reach are
frequently high (0.96<0.99) (Shaulis et al., 1994). There has been some studies12–15 into the relation
between flexibility as measured by the SR test and leg length, standing reach, reach length, and head
position during the test (Hui et al., 1999; Minkler, 1994). Although the Sit and reach (SR) test are
generally considered acceptable field test measures of hamstring flexibility for most age groups, there
are no studies of which is the best technique. Baltaci et al., 2003 studies indicate that the back saver
sit and reach test produces reasonably accurate and stable measures of hamstring flexibility.
31
2. METHODS AND METHODOLOGY
2.1. Research objects
This study was designed to investigate the effects of Muscle Energy Techniques and
Proprioceptive neuromuscular facilitation stretching on Hamstring Flexibility on soccer players and
also to determine the effects of muscle for by measuring vertical jump performance. All subjects
performed the stretching protocol on the first and second day of testing. The stretching protocol
targeted only the Hamstring muscle groups (Bicep femoris, semitendinosus and semimembranosus).
All the subjects were asked to take a measurement for muscle flexibility by using stright leg
raise(SLR) test, Active Knee Extension and Sit and Reach test before and immediately after the
stretching and after 10 minutes and average of the 3 trail were calculated. VJP (jump height) was
measured using a piezoelectric Quattro jump force platform.
All the subjects performed 3
countermovement jumps on the force platform before stretching, immediately after stretching, after
10 minutes and the average of the 3 trials were calculated. The graphs and readings were recorded.
2.2. Participants
Thirty Amateur Soccer players from football clubs were volunteered to participate in this study.
Of this group, 20 were members of Lithuanian U19 soccer team and 10were soccer players from
division football club. Subjects selected for the studies are according to the inclusion criteria.
Subjects were excluded if they have any pathology or any neural injuries or low back pain. Subjects
were recruited from FC Stumburas, Kaunas.
The athletes had no restrictions from participation in their normal practice schedule or other
activities during the course of a day. The experimental procedures and the risks involved were
explained to all the subjects and a signed informed consent was obtained the protocol was approved
by the institutional research ethics committee. All the subjects were handed a research information
sheet and given the option to withdraw at any time from the study.
32
Table 1 . Subjects descriptive data of three groups.
Groups
Age (Years) Mean
Height (cm) Mean
Weight (Kg) Mean
±SD
±SD
±SD
179.5±7.8
71.6±9.3
17.5±1.3
176.5±6.5
65.8±6.3
19.7±1.1
181.1±6.4
80±8.7
Group A(METs-PIR)
17.6±1.1
Group
B(PNF-
CRAC)
Control Group C
MET(PIR): Muscle energy technique(Post isometric Relaxation)
PNF(CRAC): Proprioceptive neuromuscular
facilitation(contract relax agonist contract)
** Non-significant
Inclusion criteria
1. Aged between 17 and 21 years.
2. HealthyMaleAmature Soccer Players
3. All participants were healthy and had no injuries before joining the study.
4. Volunteers signed the consent form to become participants.
Exclusion criteria
1. The participants were sickorinjured.
2. Participantshad a problem associated with neuro-muscular or skeletal in lower extremities.
3. Participants were not purely voluntary.
4. Participants were absent from investigation more than 20%.
2.3 Methods
Active Knee Extension (AKE) Test
The active knee extension test (AKE) was used to measure hamstring flexibility. The subject
was requested to lie in supine position with the non-tested limb and the pelvis was strapped to the
plinth for stabilization. The tested leg was positioned in 90 degrees of hip flexion and the knee flexed.
Hip flexion was maintained through the use of a crossbar to maintain the proper position of hip and
thigh (Russell, 2004). A full circle universal goniometer was used to measure the angle of knee ROM.
The fulcrum of the goniometer was centered over the lateral condyle of the femur with the fixed arm
secured along the femur using the greater trochanter as a reference. The movable arm was aligned
with the lower leg using the lateral malleolus as a reference. Subject was asked to actively extend the
tested knee as far as possible until a mild stretch sensation was felt. The procedure was repeated 3
33
times and the average was taken for analysis. Baseline, post- and follow-up measurement data on
AKE were collected from both groups.
Figure 4. Active knee extension (AKE)-90o-90o degree position
Sit and Reach Test
The SR test was performed using the procedures outlined in the ACSM manual 2. A standard
SR box was placed on the floor, by placing tape at a right angle to the 38 cm mark. The participant sat
on the floor with shoes on, and fully extended one leg so that the sole of the foot was flat against the
end of the box. She then extended her arms forward, placing one hand on top of the other. With palms
down, she reached forward sling hands along the measuring scale as far as possible without bending
the knee of the extended leg. Throughout testing, the physiotherapist checked to ensure that the heel
remained at the 45 cm mark. Three trials were performed on one side; then the participant changed
leg position and repeated the procedure on the other side. The average of the three trials on each side
was used for subsequent analyses.
Figure 5. Sit and reach test
34
Muscle Energy Techniques
Muscle energy technique Muscle energy technique was applied using post-isometric
relaxation technique. an application of MET as advocated by Chaitow (2006): the supine subject’s hip
was passively flexed and the leg extended until tension was sensed by the researcher and the subject
reported a moderate stretching sensation. The participant provided a moderate (approximately 40% of
maximal contraction) knee flexion isometric contraction, against the researcher’s shoulder for 7–10 s.
This was followed by 2–3 s of relaxation, and then the leg was passively stretched to the palpated
barrier and/or tolerance to stretch and held for 30 s. The leg was then lowered to the table for a short
resting period (approximately 10 s). To prevent an increase in blood pressure via the Valsalva
manoeuvre (chaitow, 2006) and to reduce compensatory muscle recruitment during the isometric
contraction, the participant was instructed to breathe normally and avoid hip elevation. This
procedure was repeated two more times.
Figure 6. Muscle energy techniques –Post isometric relaxation
Contract Relax Agonist Contract Technique(PNF)
With the knee in full extension, the partner gently pushed the subject's lower limb with the
kneefullyextendedintohipflexion to the point of discomfort and foot in relaxed plantar flexion. The
subject then instructed to contract the antagonist (hamstrings) maximally into extension while being
resisted by their partner for 5s. The subject then was instructed to maximally contract the agonist
(quadriceps) into flexion for 5s then relaxes; the partner then passively moved the leg further into
flexion until discomfort and held for 20 sec. This procedure was repeated twice more with a 5s rest
period between each stretch.( Hall. & Brody, 1999).
35
Figure 7.Proprioceptive neuromuscular facilitation (CRAC)
The countermovement jump
The counter-movement jump technique (as described by Church et al., 2001) was used to
measure Vertical jump height performance on the force platform. In this technique, the subjects stand
in an upright standing position with the feet shoulder width apart. Initially the subject makes a
downward movement by flexing the hips and knees and vigorously extends the hips and knees to
perform a vertical jump. The subjects were asked to keep their hands on their hips throughout the
whole push-off,flight and landing phase of the jump.
Figure 8. Countermovement Jump
Figure 9. Countermovement Jump Technique (Church et al., 2001)
36
Figure 10. Study protocol
37
2.4-Study organization
Testing took place in the exercise room of FC Stumburas soccer club,Kaunas. The subjects
reported to the exercise room on 3 separate days for all three groups. On the day of testing, all the
subjects were asked to perform static cycling for about 5 minutes at their own comfort and selfselected speed as general warm-up. After 5minutes of warm-up,subjects are than asked to measure a
Pre-test followed by strectching of the desired group than immediate post measurement.Then the
subjects were instructed to take rest for 10 minutes. Again the subjects were taken the measurement
for all three measuring tools and the readings were recorded.
2.5 Statistical Analyses
Satistical analysis was performed using SPSS version 23.0. A 2-way [mode (control group vs
METs group vs PNF group) * time (pre vs post vs after 10 min)] repeated measures analysis of
variance between subjects was used using SPSS version 23 for Windows.
Levene’s test was
performed to prove the homogeneity of variance. Three separate 2-way repeated measures for
measuring jump height, 2 methods of muscle flexibility measurement are used. Descriptive statistics
were calculated for the dependent variables (jump height, muscle flexibility) and the assumptions
were normally distributed. The statistical significant value for all analyses was set at p ≤ 0.05. The
Mauchly’s Test of Sphericity was performed to test the assumptions of sphericity. Post-Hoc test was
performed to find the relationships between groups.
38
3. RESULTS
3.1-Hamstring Flexibility
This study took two tools to measure the outcomes of Hamstring flexibility i.e. Active Knee
Extension and Sit and Reach Test. The mean changes in range of motion at pretest, post intervention and
follow-up in three groups for both measuring tools are summarized in table separately.
Active Knee Extension (AKE):
There was a notable improvement in post-stretch Muscle flexibility (figure11) was found with
Muscle energy techniques stretching Techniques (4.0%) and there was a marked improvement in
post-stretch (figure 11) with Proprioceptive neuromuscular facilitation stretching (3.3%), while there
was no significant changes in post-stretch with control group. It’s also found that muscle energy
techniques is much effective than Proprioceptive neuromuscular facilitation stretching on muscle
flexibility. Following muscle energy techniques stretching, there was an increase in ROM (2.7%,
p<0.05) post immediately, when measured after 10 minutes the ROM further increased to (4.0%,
p<0.05). Following Proprioceptive neuromuscular facilitation stretching, there was an increase in
Range of motion (2.0%, p<0.05) post immediately, when measured after 10 minutes the ROM further
increased to (3.3%, p<0.05). Statistics shows that there is significant difference with in the groups
(p<0.066), but Post Hoc Statistics for comparisons revealed that there were no significant difference
in knee range of motion between the two experiment groups .Both groups showed significant
improvements at post intervention but the improvement in muscle energy technique (P<0.569) was
better than that of PNF stretching (P<0.961).
Active Knee Extenstion(CM)
175
170
165
METs
160
PNF
155
CON
150
145
AKEpre
AKE post
FOLLOWUP
Figure 11. Mean, standard deviation of (AKE)Pre-Post ,followup ROM within Group A, B and C
39
165
163,5
162
161,3
161
METs
159
159
158,5
158,9
PNF
Control
157
156
155,8
153
PreTest
PostTest
Followup
Figure 12. Range of motion of Active Knee extension
8
6,3
5,2
4
1,9
0
Post Difference
METs
PNF
control
Figure 13.Mean difference between pre and followup-Active knee extension ranges in Three groups
40
Sit and Reach Test
There was a marked improvement in post-stretch Muscle flexibility (figure12) were
found with Muscle energy techniques stretching (8.18%, p<0.05). There was also some improvement
in post-stretch of sit and reach measurements (figure 12) with PNF stretching (5.26%, p<0.05), while
there was no marked difference in post-stretch distance with control group. It’s also found that
muscle energy techniques is much effective than that in PNF stretching on muscle flexibility.
Following METs stretching, there was an increase in Sit and Reach measurement (3.03%, p<0.05)
post measurement, when measured after 10 minutes the ROM further increased to (8.18%, p<0.05).
Following PNF stretching, there was an increase in Sit and Reach test (3.02%, p<0.05) when
measured after 10 minutes, the ROM further increased to (5.26%, p<0.05). Statistics show that there
is no significant difference within groups also post hoc comparisons revealed that there were no
significant difference in knee range of motion across the two experiment groups .Both groups showed
significant improvements at post intervention but the improvement in muscle energy technique
(P<0.301) was better than that of PNF stretching (P<0.635).
43
41
Sit and Reach test (CM)
39
37
35
METs
33
PNF
CON
31
29
27
25
AKEpre
AKE post
FOLLOWUP
Figure 14. Mean, standard deviation of (SRT)Pre-Post ,followup ROM within Group A, B and C.
41
37
35,7
35
34,5
33
33
32,4
METs
31,4
31
30,4
30,4
29,8
Control
29,1
29
PNF
27
25
PreTest
PostTest
Followup
Figure 15. Estimated Marginal Mean of Sit and Reach Test
4
2,7
2
1,3
0
Post Difference
METs
PNF
control
Figure 16 Mean PRE and POST difference stretching of Sit and reach ranges in Three groups
42
3.3-Muscle force (Vertical Height)
Hamstring muscle Force was measured by Vertical Jump height. All the players underwent
the pre jump measurement; two experiment groups were given their respective stretching techniques.
There was a significant reduction in post-stretch jump height (figure 13) were found with Muscle
energy techniques stretching (4.5%). There was a reduction in post-stretch jump height (figure 13)
with Proprioceptive neuromuscular facilitation stretching (4.3%), while there was no slight difference
in post-stretch jump height with control group. Following METs stretching, there was a decrease in
jump height (-5.6 %) when measured immediately after stretching, while the jump height there was
slight improvement in height value (-4.5 %) to the post-stretch value when measured after 10 minutes.
Following Proprioceptive neuromuscular facilitation stretching, there was a decrease in jump height
(5.3%) when measured immediately after stretching, while the jump height returned closer to the prestretch value when measured after 10 minutes. Post Hoc Statistics for comparisons revealed that there
were no significant difference in knee range of motion between the two experiment groups,( p<0.130).
45
Vertical jump Height(CM)
40
35
METs
PNF
30
CON
25
20
AKEpre
AKE post
FOLLOWUP
Figure 17 . Mean, standard deviation of (VJH)Pre-Post ,followup ROM within Group A, B and C .
43
40
39
39,2
38,5
38
37,4
37,5
37,3
37,3
37,1
37
METs
PNF
Control
36
35,7
35,3
35
34
PreTest
PostTest
Followup
Figure 18. Estimated Mean Value of Vertical Jump Height
1
Post Difference
-1
-1,5
-1,7
-3
METs
PNF
control
Figure 19.Mean PRE and POST difference stretching of Vertical jump Height ranges in Three groups
44
4. DISCUSSION
This study was a Pre-test ,Post-test Randomized controlled experimental design.Following the
Assesment of Stright Leg raising(SLR),Subjects were Randomly assigned into 3 equal groups, Group
A(Muscle
energy
Techniques-(Post
isometric
Relaxation)(n=8),Group
B(Proprioceptive
neuromuscular facilitation –(CRAC)(n=8),Group c(controlled group)(n=8). The treatment was given
as one treatment session in a day as all three groups’ measurement took place in three different days.
Measurements for three groups were taken as baseline in the 1st day as pre-test; the experimental
group performed 3*30-second stretches with a 15-second rest between stretches. Immediately after
the last stretch, subjects were positioned for post-testing and later after 10 minutes. 10 minutes Posttest measurements were taken according to previous study done by (DePino, 2000). Assessment was
done approximately at the same time in the day, in which a trained physiotherapist who was blinded
about the subject conducting all the measurements.
The review of previous studies regarding the role of different techniques in increasing muscle
flexibility reveals lots of information about the effects. There was not many studies done before
which compared the effectiveness of two stretching techniques i.e. Proprioceptive neuromuscular
facilitation-CRAC and Muscle energy techniques-Post isometric relaxation (PIR) for improving
hamstring muscle flexibility and effects on muscle force. Therefore the current study was undertaken
to analyze the effectiveness of Muscle energy technique and PNF stretching. For the aim of this
comparison a pre–posttest, follow up of the both experimental study group was carried out. Reason
behind choosing the Hamstring muscle is , Hamstring muscle is the most frequent and most prone to
injuries during the soccer games, and if the flexibility of hamstring muscle
is adequate then
possibilities of hamstrings strains injuries can be reduced and performance can be improved as well.
Additionally, there are well documented, valid and reliable methods of testing flexibility of hamstring
muscles, such as the measure of Active Knee Extension and sit and reach test. A comparison of the
pre-test and the posttest and follow-up values of the Range of motion for the groups showed that there
was a significant improvement in experimental groups. Whereas no significant improvement in
controlled groups. Thus it may be said that these technique is effective individually in improving
flexibility of hamstrings.
The present study used a 10-second cycle for the Post isometric relaxation (PIR) technique
and a 20-second cycle for Contract relax agonist contract (CRAC). The next shortest duration was a
30-second cycle of single time (Sullivan et al.,1992) followed by 4*3 20-second cycles (Worrell,
Smith, and Winegardner, 1994); 5*3 20-second cycles (Osternig et al., 1990); and 5*3 26-second
cycles (Spernoga et al., 2001).The main aim for this study was to compare the effectiveness of two
different stretching techniques for improving hamstring muscle flexibility and to find the effects of
muscle force. The measurement tools used in this studies to evaluate the hamstring flexibility is
45
active knee extension and sit and reach test for the range of motion and Vertical Jump test for
measuring the vertical jump performance of the muscle. This study shows that the hamstring
flexibility remains significantly increased after both stretching protocol for 10 minutes. Past studies
using a static stretching protocol, hamstring flexibility increased frequently but only stayed increased
for 3 minutes after stretching (DePino et al., 2000). Spernoga et al., 2001 concluded his study, that
One-time, modified contract-relax stretching protocol was effective in improving hamstring
flexibility as measured by Active knee extension. Although, the benefits of improvement in Range of
motion lasted for only lasted 6 minutes after the final stretch and this protocol may not be any more
effective than static stretching. In this study, there was a significant improving in both the
experimental groups, marking that flexibility of the hamstrings can be increased effectively by both
protocols. The study also shows that post isometric relaxation (MET) is more effective than Contract
relax agonist contract stretching for improving hamstring flexibility. The improvement in muscle
energy techniques technique may be credited to the fact that pressure in the muscle creates autogenic
inhibition over initiation of group Ib fibers, thus, causing muscle relaxation of the tight muscle.
Additionally passive extension of muscle and fascia as the joint moves in the opposite direction after
the muscle relaxes from max isometric contraction. And this is quite even with the study proposed by
Nagarwal et al., (2010). The reason for this gain in flexibility might also be the alteration in stretch
approach or resistance, as has been proposed by Sharman et al., 2006. Waseem et al., 2009 showed
that muscle energy techniques significantly increase hamstring flexibility in young males. Muscle
energy techniques (MET) improved muscle length by a mixture of creep and plastic changes in
connective tissue. It happened due to neuro-physiological or biomechanical changes or due to a raise
in grit to stretching. Biomechanical and neuro-physiological mechanism might motivate changes to
both ROM and muscle stiffness following the application of muscle energy techniques (Magnusson et
al., 1996). The neuro-physiological factor is explained by inhibition of motor activity of muscle
showing to stretch, the purpose of the stretching is to reduce muscle activity to minimize resistance to
stretching. Similarly, in this study both Muscle energy technique and Proprioceptive neuromuscular
facilitation stretching showed significant difference in Vertical jump height performance.
There was an overall (5.5%) reduction in Vertical jump height performance following METs
stretching immediately and after 10 minutes and (4.5%) reduction in VJP following PNF stretching
immediately and after 10 minutes.(Magnusson et al. (1998) stated that PNF stretching induces stretch
relaxation to the musculotendinous unit. This results in increased flexibility by increasing the slack
in the tendon. This increase in slack could affect the force production in the musculotendinous unit
due to increase in length, which has a negative effect on the length-tension relationship (Nelson &
Kokkonen, 2001; Young & Elliott, 2001). The length-tension relationship depends upon the actin
and myosin filaments. When a muscle fiber contracts from a point where there was only minimal
46
overlap between actin and myosin filament (increase in length due to stretching), the force of
contraction is minimal (Alter, 2004). Similarly, in this study, Both Muscle energy technique and
Proprioceptive neuromuscular facilitation stretching could have increased the slack, thereby
increasing the length in the tendon and decrease the contact between actin and myosin filaments,
which could have resulted in decreased Vertical jump height performance.However, this conflicts
with Church et al. (2001) findings that the PNF stretching decreased vertical jump height to a larger
extent, that is, up to 20%. But in support of the present study, Young & Elliott (2001) also stated that
PNF stretching resulted in a minimal reduction in vertical jump height. The possible reason for these
varying conclusions could be the methods followed in these studies. Church et al. (2001) used 2
repetitions of 10-second isometric contraction with 10-second passive stretch, while Young & Elliott
(2001) did only 1 repetition of a 5-second isometric contraction with 15-second passive stretch and
the current study had 3 repetitions of a 10-second isometric contraction to agonist muscle followed by
10-second isometric contraction of the agonist muscle followed by 10-second passive stretch of the
agonist muscle. And in this studies we just used the Hamstring muscle where as in previous studies
Quadriceps, Plantar flexors muscle groups and hamstrings were stretched (Bradley et al., 2007).
Moreover, Church et al. (2001) study included only female participants and Young and Elliott (2001)
had both male and female participants, while current studies had only male participants.
Therefore more research is needed to determine the effects of volume of METs and PNF
stretching on Vertical Jump performance.
47
CONCLUSIONS
1. There is no significant difference in Hamstring muscle flexibility following Muscle energy
techniques and Proprioceptive neuromuscular facilitation types of stretching. Both Muscle
energy techniques and Proprioceptive neuromuscular facilitation types of stretching are equally
effective on hamstring flexibility .
2. The current study found a no significant difference in muscle force following Muscle energy
techniques and Proprioceptive neuromuscular facilitation stretching between the groups. Both
muscle energy techniques and Proprioceptive neuromuscular facilitation stretching are equally
effective in reducing the muscle performance in vertical jump height.
48
SUGGESTIONS
Moreover, the effect of these types of stretching on Muscle flexibility and muscle force was
found up to 10 minutes. This could be a little challenging for the therapist since in most games warmups are completed at least 15 minutes before the competition. Therefore, future research could focus
on two main aspects
1. to maintain the achieved effects of stretching till the game ends.
2. the exact mechanism underlying the increase or decrease of performance following
different types of stretching on performance.
49
ACKNOWLEDGMENT
I would like to thank my Research supervisor Assoc. Prof.PhD. Sandrija Capkauskiene and Research
advisor Prof. Doc. Dr. Vilma Juodzbaliene for guiding with their expertise, Mr.Ignas for his
assistance with participants and my wife for giving me full support during my whole study.
50
REFERENCE
1.
Alonso, J.M., Junge, A, Engebretsen, L, Renström, P, Mountjoy M, Aubry M. & Dvorak J.(2008).
Injury surveillance in multi-sport events: the International Olympic Committee approach. British
Journels of Sports Medicine, 42,413–21.
2.
Alter, M.J. (2004), Science of Flexibility (3rd edition.), Human Kinetics, Champaign, IL
3.
Árnason, A., Sigurdsson, S.B., Gudmundsson, A., Holme, I , Engebretsen, L. and Bahr, R. (2004)
Risk factors for injuries in football. American Journal of Sports Medicine ,32,S5-S16.
4.
Askling C, Karlsson J, Thorstensson A. (2003) Hamstring injury occurrence in elite soccer players
after preseason strength training with eccentric overload. Scandinavian Journal of Medical Science in
Sports,13, 244–50.
5.
Avela, J., Kryolainnen, H., & Komi, P.V. (1999), Altered reflex sensitivity after repeated and
prolonged passive muscle stretching. The Journal of applied Physiology ,86, 1283-1291
6.
Awan, R., Smith, J., & Boon, J. (2002). Measuring shoulder internal range of motion: A comparison
of 3 techniques. Archives of Physical Medicine and Rehabilitation, 83, 1229-1234.
7.
Ayala, F., & Sainz de Baranda, P. (2008). Effect of duration and technique of hamstring stretching on
hip flexion range of motion]. Cultura, Ciencia y Deporte, 3, 93-99.
8.
Baechle, T. R., & Earle, R. W. (2008). Essentials of strength training and conditioning. National
Strength and Conditioning Association journal.
9.
Bahr, R & Holme, I (2003) Risk factors for sports injuries--a methodological approach. British
Journels of Sports Medicine, 37,384-392.
10.
Ballantyne F,Fryer G & McLaughlin P (2003).The effect of muscle energy technique on hamstring
extensibility:the mechanism of altered flexibility.Journal of Osteophatic Medicine 6(2),59–63.
11.
Bandy, W.D, Irion,J.M & Briggler M. (1998).The effect of static stretch and dynamic range of
motion training on the flexibility of the hamstring muscles. The Journal of orthopaedic and sports
physical therapy.;27(4):295–300.
12.
Battermann, N., Appell, H. J., Dargel, J., & Koebke, J. (2010). An anatomical study of the proximal
hamstring muscle complex to elucidate muscle strains in this region. International journal of sports
medicine, 32 (03), 211-215.
13.
Blahnik, J. (2013). Full body flexibility. Human Kinetics: Champaign, IL.
14.
Borowski,L.A, Yard, E.E, Fields, S.K, Comstock,R.D. (2008).The epidemiology of US high school
basketball injuries, 2005-2007. American journels of Sports Medicine; 36(12):2328-2335.
15.
Bradley, P.S., Olsen, P.D., & Portas, M.D.(2007), The effect of static, ballistic, and proprioceptive
neuromuscular facilitation stretching on vertical jump performance. The Journal of Strength and
Conditioning Research ;21(1), 223-226.
51
16.
Carrand, D., Gallagher, P. M., & Vardiman, P. (2010). Stretching: Does it help? Strategies: A Journal
for Physical and Sport Educators, 23(4), 32.
17.
Chan S.P., Hong Y, & Robinson P.D. (2001). Flexibility and passive resistance of the hamstrings of
young adults using two different static stretching protocols. Scandinavian Journal of Medical Science
in Sports; 11(2):81-86
18.
Christensen, B.K., & Nordstrom, B.J. (2008), The effects of proprioceptive neuromuscular facilitation
and dynamic stretching techniques on vertical jump performance. The Journal of Strength and
Conditioning Research;.22(6), 1826-1831
19.
Chumanov E.S, Heiderscheit B.C, & Thelen D.G. (2007) The effect of speed and influence of
individual muscles on hamstring mechanics during the swing phase of sprinting. Journal of
Biomechanics; 40,3555–3562.
20.
Chumanov, E.S, Schache, A.G, Heiderscheit,B.C & Thelen,D.G.(2012)Hamstrings are most
susceptible to injury during the late swing phase of sprinting. British Journels Sports Medicine: 46,
90.
21.
Church, J.B., Wiggins, M.S., Moode, F.M., & Crist, R. (2001), Effect of warm-up and flexibility
treatments on vertical jump performance. The Journal of Strength and Conditioning Research.,15(3),
332-336.
22.
Clapis, P. A., Davis, S. M., & Davis, R. O. (2008). Reliability of inclinometer and goniometric
measurements of hip extension flexibility using the modified Thomas test. Physiotherapy Theory and
Practice, 24, 135-141.
23.
Cornbleet, S. L. & Woolsey, N. B. (1996). Assessment of Hamstring Muscle Length in School-aged
Children Using the Sit-and-Reach Test and the Inclinometer Measure of Hip Joint Angle. Physical
Therapy, 76, 850-855.
24.
Croisier J.L, Forthomme B, Namurois, M.H, Vanderthommen M, & Crielaard, J.M.(2002) Hamstring
muscle strain recurrence and strength performance disorders. American journels of Sports Medicine;
30 (2): 199-203.
25.
Cross, K. M. & Worrell, T. W. (1999). Effects of a Static Stretching Program on the Incidence of
Lower Extremity Musculotendinous Strains. Journal of Athletic Training, 34, 11-14.
26.
De Paiva Carvalho, F., Prati, J., de Alencar Carvalho, M., & Dantas, E. (2009). Acute effects of static
stretching and proprioceptive neuromuscular facilitation on performance of vertical jump in
adolescent tennis. Fitness & Performance Journal (Online Edition), 8(4), 264-268.
27.
Decoster L.C, Cleland J, Altieri, & Russell (2005).The effects of hamstring stretching on range of
motion: a systematic literature reviewJournal of Orthopaedic and Sports Physical Therapy, 35,377–
387.
52
28.
DePino G, Webright W.G, & Arnold B.L( 2000) Duration of maintained hamstring flexibility after
cessation of an acute static stretching protocol. Journal of Athletic Training; 35,56–59.
29.
Dorn T.W, Schache A.G, Pandy M.G.(2012)Muscular strategy shift in human running: dependence of
running speed on hip and ankle muscle performance , Journal of Experimental Biology. 215, 1944–
1956.
30.
Drezner J.A. (2003) Practical management: hamstring muscle injuries. Clinical Journal of Sport
Medicine; 13: 48 – 52.
31.
Dvorak J, Junge A, Chomiak J, et al. 2000.Risk factor analysis for injuries in football players—
possibilities to design a preventive program. American Journal of Sports Medicine , 28 (5)69–74.
32.
Ekstrand J., Hagglund M., Walden M. (2011). Injury incidence and injury pattern in professional
football—the UEFA injury study. British Journal of Sports Medicine, 45 (7), 553-558.
33.
Evetovich, T.K., Nauman, N.J., Conley, D.S., & Todd, J.B (2003), Effect of static stretching of the
biceps brachii on torque, electromyography, and mechanomyography during concentric isokinetic
muscle actions. The Journal of Strength and Conditioning Research ..17(3), 484-488
34.
Feland, J. B. & Marin, H. N. (2004). Effect of submaximal contraction intensity in contract-relax
proprioceptive neuromuscular facilitation stretching. British Journal of Sports Medicine, 38.
35.
Feland, J. B., Myrer, J. W., & Merrill, R. M. (2001). Acute changes in hamstring flexibility: PNF
versus static stretch in senior athletes. Physical Therapy in Sport, 2, 186-193.
36.
Fletcher, I.M., & Jones, B. (2004), The effect of differential warm-up stretching protocols on 20
meter sprint performance in trained rugby union players.
The Journal of strength &
conditioning,18,885-888
37.
Fowles, J.R., Sale, D.G., & MacDougall, J.D. (2000), Reduced strength after passive stretch of the
human plantarflexors. The Journal of Applied Physiology ,89, 1179-1188.
38.
Funk DC, Swank AM, Mikla BM, Fagen TA, Farr BK.(2003) Impact of Prior Exercise on Hamstring
Flexibility:
A
Comparison
of
Proprioceptive
Neuromuscular
Facilitation
and
Static
Stretching. National Strength and Conditioning Association journal. ;17(3):489–492.
39.
Gabbe, B. J., Bennell, K. L., Wajswelner, H., & Finch, C. F. (2004). Reliability of common lower
extremity musculoskelet al screening tests. Physical Therapy in Sport, 5, 90-97.
40.
Gajdosik, R. (2001). Passive extensibility of skeletal muscle: Review of the literature with clinical
implications. Clinical Biomechanics, 16, 87-101.
41.
Garrett W.E, Jr(1996) Muscle strain injuries. The American Journal of Sports Medicine, 24(6):S2–S8
42.
Greenman P. (1996)Principles of Manual Medicine. 2nd ed. Philadelphia, PA: Lippincott Williams &
Wilkins.
53
43.
Gribble P.A, Guskiewiez K.M, Prentice W.E, Shields E.W.(1999): Effects of static and hold —relax
stretching on hamstring range of motion using the Flexibility LE1000. Journal of Sport
Rehabilitation; 8 (3).
44.
Hägglund M, Waldén M, Ekstrand J,(2009). Injuries among male and female elite football players.
Scandinavian Journal of Medical Science in Sports, 19(6):819-827.
45.
Hagglund M., Walden M., Ekstrand J. (2012). Risk factors for lower extremity muscle injury in
professional soccer- The UEFA injury study. The American Journal of Sports Medicine, 20(10), pp.
1-9.
46.
Handel M, Horstmann T, Dickhuth HH, et al.(1997) Effects of contract-relax stretching training on
muscle performance in athletes European Journal of Applied Physiology, 76: 400–408.
47.
Harman, E.A., Rosenstein, M.T., Frykman, P.N., & Rosenstein, R.M. (1990), The effects of arms and
countermovement on vertical jumping. The Journal of Medicine & Science in Sports & Exercise, 22,
825-833
48.
Hartig DE, Henderson JM. (1999) Increasing hamstring flexibility decreases lower extremity overuse
in military basic trainees. American Journal of Sports Medicine;volume 27:173–6.
49.
Heiderscheit BC, Hoerth DM, Chumanov ES, Swanson SC, Thelen BJ, Thelen DG.
(2005),Identifying the time of occurrence of a hamstring strain injury during treadmill running: a case
study. Clinical Biomechanics (Bristol, Avon): 20: 1072–1078.
50.
Heiderscheit BC, Sherry MA, Silder A, Chumanov ES, Thelen DG.(2010)Hamstring strain injuries:
recommendations for diagnosis, rehabilitation, and injury prevention. Journal of Orthopedic and ,
Sports Physical Therapy;40(2):67-81.
51.
Henderson, G., Barnes, C. A., & Portas, M. D. (2010). Factors associated with increased propensity
for hamstring injury in English Premier League soccer players. Journal of Science and Medicine in
Sport, 13, 397-402.
52.
Herbert, R.D., & Gabriel, M. (2002). Effects of stretching before and after exercising on muscle
soreness and risk of injury: Systematic review. British Medical Journal, 325;468-473.
53.
Holcomb, W. (2000), Essentials of Strength Training and Conditioning (2nd ed.), Human Kinetics,
Champaign: IL.
54.
Hunter, J.P., & Marshall, R.N. (2002), Effects of power and flexibility training on vertical jump
technique. The journal of Medicine & Science in sports & exercise vol. 34, no. 3, pp. 478-486
55.
Jaggers, J. R., Swank, A. M., Frost, K. L., & Lee, C. D. (2008). The acute effects of dynamic and
ballistic stretching on vertical jump height, force, and power. Journal of Strength and Conditioning
Research, 22(6), 1844-9.
56.
Jarvinen,T.A.H., Jarvinen, T.L.N., Kaariainen, M., Kalimo, H., Jarvinen, M. (2005).Muscle injuries:
biology and treatment. American Orthopaedic Society for Sports Medicine, 33(5), pp. 745-763.
54
57.
Johansson, P. H., Lindström, L., Sundelin, G. & Lindström, B. (1999), The effects of preexercise
stretching on muscular soreness, tenderness and force loss following heavy eccentric exercise.
Scandinavian Journal of Medicine & Science in Sports, 9: 219–225.
58.
Kent, M. (2006). Ballistic stretching. The oxford dictionary of sports science & medicine: Oxford
University Press.
59.
Knudson, D., Bennett, K., Corn, R., Leick, D., & Smith, C.(2001), Acute effects of stretching are not
evident in the kinematics of the vertical jump. The Journal of Strength and Conditioning Research
15, 1, 98-101
60.
Kolt, G. S. & Snyder-Mackler, L. (2007). Physical Therapies in Sport and Exercise. (Second Ed.)
Churchill Livingstone Elsevier.
61.
Kordi R, Hemmati F, Heidarian H, Ziaee V.(2011) Comparison of the incidence, nature and cause of
injuries sustained on dirt field and artificial turf field by amateur football players. Sports Medicine
Arthroscopy Rehabilitation Therapy & Technology;3(1):3.
62.
Lally, D.A. (1994), Stretching and injury in distance runners. The Journal of Medicine & Science in
Sports & Exercise,. 26, S84
63.
Lara, A.J., Abian, J., Alegre, L.M., Jimenez, L., & Aguado, X. (2006), Assessment of power output in
jump tests for applicants to a sports sciences degree. The Journal of Sports Medicine and Physical
Fitness ,. 46, 3,419-424
64.
Leon Chaitow, Judith Walker Delany. Clinical application of neuromuscular techniques. Volume 1,
the upper body; Forwarded by John Lowe and Benny Vaughn, Churchill Livingstone. 2000.
65.
Liebesman, J., & Cafarelli, E. (1999), Physiology of range of motion in human joints: A critical
review. The Journal of Critical Review in Physical and Rehabilitation Medicine ,6, 131-160.
66.
Linthorne, N.P. (2001), Analysis of standing vertical jump using a force platform. The Americal
Journal of Physics , 69, 11,1198-1204
67.
Little, T., & Williams, A.G. (2006), Effects of differential stretching protocols during warm-ups on
high-speed motor capabilities in professional soccer players.
The Journal of Strength and
Conditioning Research ,20, 1203-207
68.
Maddigan ME, Peach AA, Behm DG (2012) A comparison of assisted and unassisted proprioceptive
neuromuscular facilitation techniques and static stretching.The Journal of Strength & Conditioning
Research. 26(5):1238-44.
69.
Madeleine Smith, Gary Fryer;(2008)A comparison of two muscle energy techniques for increasing
flexibility of the hamstring muscle group. Journal of Bodywork and Movement Therapies, 6.
70.
Magnusson SP, Aagaard P, Larsson B, Kjaer M. ( 2000)Passive energy absorption by human muscletendon unit is unaffected by increase in intramuscular temperature. Journal of Applied Physiology; 88:
1215–1220.
55
71.
Mahieu N.N., McNair P., De Muynck M., et al. (2007). Effect of static and ballistic stretching on the
muscle-tendon tissue properties. Medicine & Science in Sports & Exercise, 39(3), 494-501.
72.
Manoel, M.E., Harris-Love, M.O., Danoff, J.V., & Miller, T.A. (2008), Acute effects of static,
dynamic, and proprioceptive neuromuscular facilitation stretching on muscle power in women. The
Journal of Strength and Conditioning Research 22, 5, 1528-1534
73.
Marek, S.M., Cramer, J.T, Fincher, A.L., Massey, L.L., Dangelmaier, S.M., Purkayastha, S., Fitz,
K.A., & Culbertson, J.Y. (2005), Acute effects of static and proprioceptive neuromuscular facilitation
stretching on muscle strength and power output. The Journal of Athletic Training 40, 2, 94-103
74.
Markovic G., Jukic I., Milanovic D.(2007) Effects of sprint and plyometric training on muscle
function and athletic performance. Journal of Strength and Conditioning Research;21, 543-549.
75.
Mason DL, Dickens V, Vail A. (2007) Rehabilitation for hamstring injuries. The Cochrane Database
of Systematic Reviews.
76.
McGarr, C. (2007). Stretching the truth. Men's Fitness;volume- 23(2), 29.
77.
McHugh, M.P., & Cosgrave, C.H. (2010). To stretch or not to stretch: the role of stretching in injury
prevention and performance. Scandavian Journal of Medicine & Science in Sports, 20, 169-181.
78.
McMillan, D.J., Moore, J.H., Hatler, B.S., & Taylor, D.C. (2006), Dynamic Vs Static-stretching
warm up: The effect on power and agility performance. The Journal of Strength and Conditioning
Research 20, 3, 492-499
79.
Mikesky, A. E., Bahamonde, R. E., Stanton, K., Avley, T., & Fitton, T. (2002). Acute effects of The
Stick on Strength, Power and Flexibility. Journal of Strength and Conditioning Research, 16, 446450.
80.
Miller SL, Gill J, Webb GR.(2007)The proximal origin of the hamstrings and surrounding anatomy
encountered during repair. A cadaveric study. The Journal of bone and joint surgery. American;
89:44-48
81.
Morán, O. & Arechabala, I. (2009). Stretching exercises encyclopedia. Maidenhead: Meyer & Meyer
Sport.
82.
Nagarwal A.K.1, Zutshi K, Ram C. S, Zafar R.(2010)Improvement of Hamstring Flexibility: A
Comparison between Two PNF Stretching Techniques, International Journal of Sports Science and
Engineering ,04 ,01, 025-033
83.
Nelson, A.G., & Kokkonen, J. (2001), Acute ballistic muscle stretching inhibits maximal strength
performance. Research Quarterly for Exercise & Sports , 72, 415-419
84.
Nelson, A.G., Gullory, I.K., Cornwell, A., & Kokkonen, J. (2001), Inhibition of maximal voluntary
isokinetic torque production following stretching is velocity-specific. The Journal of Strength and
Conditioning Research ,15, 1, 241-246
56
85.
Nordez, A., Cornu, C., & McNair, P. (2006). Acute effects of static stretching on passive stiffness of
the hamstring muscles calculated using different mathematical models. Clinical Biomechanics, 21,
755-760.
86.
O'Hora, J., Cartwright, A., Wade, C. D., Hough, A. D., & Shum, G. L. K. (2011). Efficacy of Static
Stretching and Proprioceptive Neuromuscular Facilitation Stretch on Hamstrings Length After a
Single Session. Journal of Strength and Conditioning Research, 25, 1586-1591.
87.
Okragly, R. A. (2011). Static Stretching. In L. J. Micheli (Ed.), Encyclopedia of sports medicine ,4,
1397-1398).
88.
Orchard J and Seward H. (2002): Epidemiology of injuries in the Australian football league, seasons
1997-2000. British Journal of Sports Medicine , 36, 39-44.
89.
Papadopoulos, G., Siatras, T. & Kellis, S. (2005). The effect of dynamic stretching exercise on the
maximal isokinetic strength of the knee extensors and flexors. Isokinetics and Exercise Science, 13,
285-291..
90.
Petersen J, Thorborg K, Nielsen MB, Budtz-Jørgensen E, Hölmich P.(2011), Preventive effect of
eccentric training on acute hamstring injuries in men's soccer: a cluster-randomized controlled trial.
American journels of Sports Medicine , 39,2296-2303.
91.
Phil
Page,(2012),Current
Concepts
In
Muscle
Stretching
For
Exercise
And
Rehabilitation,International Journels Sports Physio Theraphy;volume 7(1): 109–119.
92.
Power, K., Behm, D., Cahill, F., Carroll, M., & Young, W. (2004), An acute bout of static stretching:
Effects on force and jumping performance. The Journal of Medicine & Science in Sports & Exercise
36, 8, 1389-1396
93.
Proske, U., Morgan, D. L., Brockett, C. & Percival, P. (2004). Identifying athletes at risk of
hamstring strains and how to protect them. Clinical and Experimental Pharmacology and Physiology,
volume 31, 546-550.
94.
Rahnama N.(2011). Prevention of football injuries. International journal of preventive medicine; 2(1):
38-40.
95.
Rakos, D. M., Shaw, K. A., Fedor, R. L., LaManna, M., Yocum, C. C., & Lawrence, K. J. (2001).
Interrater Reliability of the Active-Knee-Extension Test for Hamstring Length in School-Aged
Children. Pediatric Physical Therapy, 13, 37-41.
96.
Reid, D. A. & McNair, P. J. (2004). Passive Force, Angle, and Stiffness Changes after Stretching of
Hamstring Muscles. Medicine and Science in Sports and Exercise, 36, 1944-1948.
97.
Ryan, E. D., Beck, T. W., Herda, T. J., Hull, H. R., Hartman, M. J., Stout, J. R., & Cramer, J. T.
(2008). Do practical durations of stretching alter muscle strength? a dose-response study. Medicine
and Science in Sports and Exercise, 40(8), 1529-1537.
57
98.
Schuback, B., Hooper, J., & Salisbury, L. (2004). A comparison of a self-stretch incorporating
proprioceptive neuromuscular facilitation components and a therapist-applied PNF technique on
hamstring flexibility. Physiotherapy,90, 151-157.
99.
Sharman M, Cresswell A, Riek S. (2006)Proprioceptive Neuromuscular Facilitation Stretching:
Mechanisms and Clinical Implications. Sport Medicine,36(11):929–939.
100.
Shehab, R., Mirabelli, M., & Gorenflo, D. (2006). Pre-exercise stretching and sports related injuries:
knowledge, attitudes and practices. Journal of Sports Medicine, 16(3), 228-231.
101.
Shehab, R., Mirabelli, M., & Gorenflo, D. (2006). Pre-exercise stretching and sports related injuries:
knowledge, attitudes and practices. Journal of Sports Medicine, 16(3), 228-231.
102.
Shrier, I. (2004), Does stretching improve performance? A systematic and Critical Review of the
literature. The clinical journal of sports medicine ,14, 5, 267-273.
103.
Shrier, I. (2005). When and whom to stretch? Gauging the benefits and drawbacks for individual
patients. The Physician and Sportsmedicine, 21(3)
104.
Small, K., Mc Naughton, L. & Matthews, M. (2008). A systematic review into the efficacy of static
stretching as part of a warm-up for the prevention of exercise-related injury. Research in Sports
Medicine, 16, 213-231..
105.
Smith, L. L., Brunetz, M. H., Chenier, T. C., McCammon, M. R., Houmard, J. A., Franklin, M. E., et
al. (1993). The effects of static and ballistic stretching on delayed onset muscle soreness and creatine
kinase. Research Quarterly For Exercise And Sport. 64, 103–107.
106.
Spernoga, S. G., Uhl, T. L., Arnold, B. L., & Gansneder, B. M. (2001). Duration of maintained
hamstring flexibility after a one-time modified hold-relax stretching protocol. Journal of Athletic
Training, 36, 44-48.
107.
Sreekaarini I, Eapen C, Zulfeequer CP.(2014) Prevalence of Sports Injuries in Adolescent Athletes.
Journal of Athletic Enhancement; 3:5.
108.
Stanton, P., & Purdam, C. (1989). Hamstring injuries in sprinting-The role of eccentkic exercise.
Journal of Orthopedic and , Sports Physical Therapy, volume 10,343-349.
109.
Stewart, D., Macaluso, A., & De Vito, G. (2003), The effect of an active warm-up on surface EMG
and muscle performance on healthy humans. The European Journal of Applied Physiology volume
89, pp. 509-513
110.
Sullivan, M. K., Dejulia, J. J., & Worrell, T. W. (1992). Effect of pelvic position and stretching
method on hamstring muscle flexibility. Medicine and Science in Sports and Exercise, 24, 1383-1389.
111.
Surburg P R; Schrader J W. Proprioceptive Neuromuscular Facilitation Techniques in Sports
Medicine: A Reassessment. Journal of Athletic Training. 1997, 32(1)
112.
Taylor, D. C., Brooks, D. E., & Ryan, J. B. (1997). Viscoelastic characteristics
58
113.
Thacker, S.B., Gilchrist, J., Stroup, D.F., & Kimsey, Jr., C.D. (2004). The impact of stretching on
sports injury risk: a systematic review of the literature. Medicine & Science In Sports & Exercise,
36(3), 371-378.
114.
Thompson, R. C. (2007), Prevention Practice. SLACK Incorporated: New Jersey.
115.
Tsolakis, C., Douvis, A., Tsigganos, G., Zaharogiannis, E. and Smirni-otou A. (2010a) Acute effects
of stretching on flexibility, power and sport specific performance in fencers. Journal of Human
Kinetics,26, 105-114,
116.
Tubbs RS, Caycedo FJ, Oakes WJ, Salter EG.(2006) Descriptive anatomy of the insertion of the
biceps femoris muscle. Clinical Anatomy; 19: 517-521.
117.
Unick, J., Kieffer, S., Cheesman, W., & Feeney, A. (2005), The acute effects of static and ballistic
stretching on vertical jump performance in trained women. The Journal of Strength and Conditioning
Research ,19, 1, 206-212
118.
Van Beijsterveldt AMC, Stubbe JH, Schmikli SL, van de Port IGL, Backx FJG (2014) Differences in
injury risk and characteristics between Dutch amateur and professional players. Journal of Science
and Medicine in Sport;18, 2.
119.
van Beijsterveldt AMC, van de Port IGL, Krist MR, et al.(2012) Effectiveness of an injury prevention
programme for adult male amateur soccer players: a cluster-randomised controlled trial. British
Journels Sports Medicine;46(16):1114-1118.
120.
Verrall GM, Slavotinek JP, Barnes PG and Fon GT. (2003): Diagnostic and prognostic value of
clinical findings in 83 athletes with posterior thigh injury. Comparison of clinical findings with
magnetic resonance imaging documentation of hamstring muscle strain. American Journal of Sports
Medicine , 31: 969-973.
121.
Verrall GM, Slavotinek JP, Barnes PG, Fon GT, Spriggins AJ.(2001),Clinical risk factors for
hamstring muscle strain injury: a prospective study with correlation of injury by magnetic resonance
imaging.British Journels Sports Medicine. 2001,35(6):435-9.
122.
Walden M, Hagglund M, Magnusson H, Ekstrand J.(2011) Anterior cruciate ligament injury in elite
football: A prospective three-cohort study. Knee Surgery, Sports Traumatology, Arthroscopy;issues
19:11-19
123.
Wallin D, Ekblom B, Grahn R, et al. (1985): Improvement of muscle flexibility. A comparison
between two techniques. American Journels of Sports Medicine, 13: 263–268
124.
Wallmann, H.W., Mercer, J.A., & McWhorter, J.W. (2005), Surface electromyographic assessment of
the effects of static stretching on the gastrocnemius on vertical jump performance. The Journal of
Strength and Conditioning Research ,19, 3, 684-688.
125.
Wassim M, Nuhmani S,Ram.CS(2009),Efficacy of muscle energy technique on hamstring muscles
flexibility in normal Indian collegiate males, Calicut Medical Journal; 7, 4.
59
126.
Webright, W. G., Randolph, B. J., & Perrin, D. H. (1997). Comparison of Nonballistic Active Knee
Extension in Neural Slump Position and Static Stretch Techniques on Hamstring Flexibility. Journal
of Orthopaedic and Sports Physical therapy,26,7-13.
127.
Weerapong, P., Hume, A. P., & Kolt, G. S. (2004). Stretching: Mechanisms and benefits for sport
performance and injury prevention. Physical Therapy Reviews, 9, 189-206.
128.
Weijer C.D, Gorniak PT.(2003) The effect of static stretch and warm-up exercise on hamstring length
over the course of 24 hours. Journal of Orthopaedic and Sports Physical therapy.: 33: 727-33.
129.
Wisloff, U., Castagna, C., Helgerud, J., Jones, R., & Hoff, J. (2004), Strong correlation of maximal
squat strength with sprint performance and vertical jump height in elite soccer players. The British
Journal of Sports Medicine ,38, 285-288
130.
Witvrouw, E., Mahieu, N., Daneels, L., & McNair, P. (2004). Stretching and injury prevention an
obscure relationship. Journal of Sports Medicine, 34(7), 443- 449.
131.
Wong P, Hong Y, Soccer injuries in the lower extremities 2005 , British Journels Sports Medicine, 39,
473-482.
132.
Woods C, Hawkins RD, Maltby S, Hulse M, Thomas A, Hodson A. (2004) The Football Association
Medical Research Programme: an audit of injuries in professional football--analysis of hamstring
injuries. British Journels Sports Medicine, ;38(1):36–41.
133.
Worrell TW, Perrin DH. Hamstring muscle injury: the influence of strength, flexibility, warm-up, and
fatigue. Journal of Orthopaedic and Sports Physical Therapy .,16:12–18.
134.
Worrell, T. W., Smith, T. L., & Winegardner, J. (1994). Effect of hamstring stretching on hamstring
performance. Journal of Orthopaedic and Sports Physical Therapy, 20, 154-159.
135.
Yamaguchi, T., & Ishii, K. (2005), Effects of static stretching for 30 seconds and dynamic stretching
on leg extension power. The Journal of Strength and Conditioning Research ,19, 3, 677-683
136.
Youdas JW, Budach BD, Ellerbusch JV, Stucky CM, Wait KR, Hollman JH. (2010).Comparison of
muscle-activation patterns during the conventional push-up and Perfect Pushup™ exercises. The
Journal of Strength and Conditioning Research, 24(12):3352–3362.
137.
Young, W. and Behm, D. (2002) Should static stretching be used during a warm-up for strength and
power activities? Strength and Conditioning Journal 24, 33-37.
138.
Young, W., & Elliott, S. (2001), Acute effects of static stretching, proprioceptive neuromuscular
facilitation stretching and maximal voluntary contractions on explosive force production and jumping
performance. Research Quarterly for Exercise & Sports ,72, 273-279
139.
Yuktasir, B., & Kaya, F. (2007), Investigation into the long-term effects of static and PNF stretching
exercises on range of motion and jump performance. The Journal of Bodywork and Movement
Therapies ,13, 11-21.
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ANNEXURE
61
PARTICIPANT INFORMATION SHEET
Dear Participant,
You are being invited to take part in a research project. Before you decide to participate
it is important for you to understand why the research is being done and what it will involve. Please
take time to read the following information carefully and discuss it with others if you wish. Ask if
anything is unclear or if you would like more information.
The aim of this project is to compare the effects of Muscle Energy Techniques and PNF
stretching on Hamstring Muscle Flexiblity on sportsperson.If you do decide to take part, you will be
given this information sheet to keep and be asked to sign a consent form.
For this research, the subject should attend two testing sessions on two separate days with at least two
days gap in between each testing. Each testing session would last for about 20 to 25 minutes. The
testing procedure includes warm-up for 5 minutes and two different forms of stretching focusing on
the lower limb muscle groups.
The subjects will be asked to measure the Hamstring Muscle
Measurement before and after the stretching protocol and the readings were noted.
If you decide to participate in this study, your participation and any information collected from
you will be strictly confidential, and only available to the research team.
We would like to thank you, in advance, for your participation.
Yalayar Shaik Kader Sultan Mohamed Arshadh
Email id: [email protected]
Thesis Supervisor –Prof .Doc. Dr. Sandrija Čapkauskienė
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PARTICIPANT CONSENT FORM
CONSENT STATEMENT
1. I understand that my participation is voluntary and that I may withdraw from the research at any
time, without giving any reason.
2. I am aware of what my participation will involve.
3. I understand that there are no risks involved in the participation of this study.
4. All questions that I have about the research have been satisfactorily answered.
I agree to participate.
Participant’s signature: __________________________________
Participant’s name:-__________________________________
Tick this box if you would like to receive a summary of the results by e-mail
E-mail: _____________________
Age:-________
Date: __________
Height:-___________ Weight:-_________
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