Download Welsh Athletics National Hamstring Strategy

Welsh Athletics
National Hamstring Strategy
Contents
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Page
1.0
Background to the strategy
3
2.0
Aims of the strategy
3
3.0
Anatomy of the Hamstring Muscle Complex
3
4.0
Function of the Hamstring Muscle Complex in sprinting
5
5.0
Incidence of Hamstring Injuries in Athletics
6
6.0
British Athletics Muscle Injury Classification System
6
7.0
Return to Training Following Hamstring Injury
7
7.1
Re-injury
7
8.0
Risk Factors for Hamstring Injury
8
9.0
How will the aims of the strategy be delivered/achieved?
9
9.1
3 Strand approach
9
10.0
How will the effectiveness of the strategy be measured?
9
11.0
Reference Tools
9
12.0
References
10
Figure 1. Pictorial depiction of the anatomy of the hamstring muscle complex
4
Figure 2. Schematic image of the proximal hamstring complex origin.
4
Figure 3. Schematic representation of the muscle - tendon complex of the long head
of biceps femoris.
5
Figure 4. Figure 3. The British Athletics Muscle injury Classification System.
7
Figure 5. A Table to show the average time to return to full training in days in different
British Athletics Muscle Injury Classifications
8
Appendix A. Detailed Anatomy of the Hamstring Muscle Complex
11
Appendix B. Guideline for hamstring injury rehabilitation through the stages of healing
13
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1.0 Background to the strategy
Hamstring injuries are common in track and field, football, rugby and other sports requiring sprinting, acceleration and kicking. They result in significant time loss from
sport, but despite recent efforts in the area of prevention and management, hamstring
injury and re-injury rates remain high.
A recent study showed 48.2% of all injuries sustained during track and field competition
were attributed to muscle injuries, with the hamstring group being the most commonly
affected (Alonso et al 2012). Anatomical and functional aspects of the hamstring muscle
complex predispose it to injury, including the fact that the muscles cross two joints and
undergo eccentric (lengthening) contraction during the gait cycle. Injury may occur anywhere between the origins of the muscles to the various insertions of the hamstring muscle complex.
Ahead of the XXI Gold Coast Commonwealth Games 2018, Welsh Athletics will endeavour to support and prevent hamstring injuries in its supported athlete population and the wider
athletics
community in Wales as part of its strategic plan.
This strategy is designed as a reference tool to aid coach, athlete and therapist education with
the primary aim of reducing the incidence and time loss from hamstring injuries in the athletic
population within Wales.
2.0
Aims of the strategy
The aims of this strategy are to;
• Reduce the incidence of hamstring injuries and re-injuries sustained by Welsh Athletics
supported athletes through a systematic process of education.
• Reduce time loss (training and competition) from hamstring injuries in Welsh Athletics
supported athletes through an education program on rehabilitation to target personnel.
• Implement a monitoring process of Welsh Athletics funded athletes training at satellite
centres.
• Promote regular objective screening of athletes by coaches in an attempt to highlight risk
factors and encourage training session modification based on findings.
• Promote the health and monitoring of athletes prior to entering the Welsh Athletics/British
Athletics support systems in an attempt to reduce one of the main risk factors for injury previous injury.
• Data collection of trends in hamstring injury with a view to publishing any relevant data to the
wider community.
3.0
Anatomy of the Hamstring Muscle Complex
The hamstring muscle complex (HMC) consists of three large muscles on the back of the thigh.
The biceps femoris is found laterally, with the semimembranosus (SMB) and semitendinosus (ST)
found medially as seen in Figure 1. These muscles are notable for the fact that they cross two
joints and have long proximal (upper) and distal (lower) tendons with resultant long muscle tendon
junctions that extend well into the muscle bellies, facilitating transmission and
dissipation
of forces across the muscle during muscle contraction and relaxation. The long
nature of the
hamstring tendons leads to a greater ‘‘spring’’ effect that enhances athletic performance but
increases injury risk. The interface between the muscle fibres and the
relatively stiff tendon
fibres is the weakest point of the muscle tendon unit (Linklater et al, 2010).
Hamstring muscle fibres are notable for containing a relatively large proportion of fast twitch
fibres that enable a relatively short time to develop peak muscle tension, allowing faster muscle
contractions, of greater intensity, in an anaerobic environment.
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Figure 1. Pictorial depiction of the anatomy of the hamstring muscle complex.
The three hamstring muscles originate close to one another from the ischial tuberosity (sitting
bone) of the pelvis as seen in Figure 2. A joint semitendinosus-biceps femoris tendon extends from
the attachment before separate biceps femoris and semitendinosus tendons become
evident.
Figure 2. Schematic image of the proximal hamstring complex origin.
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The biceps femoris can be divided into two portions; the long head (lhBF) and short head (shBF).
The lhBF originates as part of the joint tendon with semitendinosus, its fibres then run
downwards to attach into the lateral side of the knee. The upper and lower tendons of lhBF are relatively long, with the lower tendon being one of the longest of all tendons within the HMC. It is
considered that the upper and lower tendons of lhBF overlap as seen in Figure 3. This may be a
feature that predisposes it to greater injury risk than the other two muscles of the HMC. The shBF
arises from the shaft of the femur, just below the gluteus maximus, its fibres also run downwards
and insert into the lateral part of the knee (Linklater et al, 2010).
Figure 3. Schematic representation of the muscle - tendon complex of the lhBF
The semitendinosus originates as part of the joint tendon with biceps femoris, its fibres run downwards and form a long, thin lower tendon inserting into the upper part of the inside of the lower
leg.
Semimenbranosus originates from the ischial tuberosity (sitting bone) separate to the joint tendon of biceps femoris and semitendinosus, its fibres also travel downwards attaching into the
inside part of the lower leg.
A more detailed description of the hamstring muscle complex can be found in Appendix A.
4.0
Function of the Hamstring muscle complex in Sprinting
The commonly thought of function of the hamstring muscle complex is to produce knee flexion
and hip extension. In movement, however, particularly in high speed running and sprinting, one
of the primary functions of the hamstring muscle complex is to decelerate the lower leg through
terminal swing phase. With the bi-articular hamstring muscles spanning the hip and knee, they
contribute to the movements exerted about both joints simultaneously. The hamstring muscles
undergo a stretch–shortening cycle during sprinting. The stretch or lengthening phase occurs during terminal swing when the hip flexes and the knee extends, while the shortening phase occurs just before foot strike and continues throughout stance when the hip extends and the knee
flexes.
The load on the HMC is found to be greatest during terminal swing just before foot strike. At this time in
the stride cycle, ST, SMB, and lhBF all reach peak muscle-tendon strain (lengthening whilst active), produce
peak muscle-tendon force, and perform much negative work. The lhBF has the largest peak muscle-tendon
strain (12.0% increase in length from upright stance position), ST displayed the greatest muscle-tendon
lengthening velocity, and SM produced the highest muscle-tendon force, absorbed and generated the most
muscle-tendon power, and
performed the largest amount of positive and negative work (Schache et al,
2012).
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Although the lhBF undergoes the greatest lengthening through terminal swing, this lengthening
doesn't seem to increase with accompanying increases in speed. Other parameters such as force
generation and absorption did. For instance, an increase in running speed from 80% to maximum
was associated with an increase in net hamstring muscle force and energy absorption during terminal swing of 1.4 and 1.9 fold, respectively (Schache et al, 2012). With the majority of hamstring
injuries occurring to the lhBF in this phase, it can be assumed that the ability of the muscle to
deal with the forces required during lengthening seem to be an important injury predictor rather
than the length of the muscle itself.
Schache et al’s (2012) in-depth study into hamstring kinematics whilst sprinting reported that the
hamstring muscles lengthened from early swing until terminal swing, after which they shortened
and continued to do so for the duration of stance. Peak muscle-tendon strain for lhBF during
sprinting exceeded the peak values for SMB and ST by 2.2% and 3.3%, respectively. Furthermore,
the time of peak muscle-tendon strain for lhBF preceded that for SMB and ST by approximately
1.5% of the stride cycle. It can therefore be assumed that peak loading of lhBF occurs prior to
any of the other muscles and gets injured more often due to the fact it reaches its tolerance point
prior to any of the other muscles in the HMC.
It can be highly postulated that because the bi-articular hamstring muscles all reach peak
muscle-tendon strain, produced peak muscle-tendon force, and performed much negative work
during the terminal swing phase of sprinting, it would seem that the hamstrings are likely to be
most vulnerable to injury at this time in the stride cycle. Unlike concentric contractions, eccentric
contractions have been shown to be capable of producing muscle fibre damage. It seems sensible
then to have a hamstring strengthening program that promotes the ability of the hamstrings to
deal with these lengthening forces at the hip and knee joints.
5.0
Incidence of Hamstring Injuries in Athletics
It is widely acknowledged that hamstring injuries make up a significant percentage of time loss
injuries in athletics. In their recent publication, British Athletics reported 65 hamstring injuries in
44 out of 230 athletes. This consisted of 31 sprinters, 8 vertical/horizontal jumpers, 3 middle
distance athletes, 1 thrower and 1 endurance runner (Pollock et al, 2015). This consisted of 28
males (63.6%) and 16 females (36.4%), and the mean age was 23.8 (SD=4.3, range 18–39) years.
Fourteen of the athletes suffered two or more separate injuries. There were 8 injuries in the
proximal third, 18 in the central third and 18 in the distal third. The most commonly injured
muscle was the long head of biceps femoris (n=28). Other injuries were to the semitendinosus,
semimembranosus, biceps femoris short head or multiple muscles
In agreement with this, Askling et al (2007) reported a distinction between two injury mechanisms
leading to injury in different muscles of the hamstring muscle complex at a different site in sprinters. Asking et al (2007) reported that all 18 hamstring injuries specifically encountered in their
high speed running population of athletic sprinters affected the lhBF. Eight (44%) of the athletes
had a secondary injury with 7 of these occurring in ST and 1 occurring in the shBF. 12 of the
primary injures to lhBF we located at the proximal MTJ and/or proximal tendon at an average 7cm
distal to the ischial tuberosity, whilst the remaining 6 were located in the distal MTJ, distal tendon
or distal muscle belly.
The Welsh Athletics Injury Audit 2015/16 (domestic indoor season) highlighted that 35% of all time
loss injures from 1st September 2015 to 29th February 2016 were muscles injuries, with 100% of
these muscle time loss injuries affecting the hamstring muscle complex. The Welsh Athletics Injury
Audit is comparable with previous research, with biceps femoris being affected in 85% of our cases.
Of these muscle injuries, 42% of the athletes affected were from the sprints/hurdles disciplines,
with 29% occurring in jumps and 29% occurring in endurance athletes.
The reason for the predominance of hamstring injuries in these particular parts of the hamstring
muscle complex have been attributed to the muscles undergoing the most amount of eccentric
lengthening at the end of the swing phase, with the long, overlapping, relatively stiff proximal
and distal tendons of lhBF contributing to the tiger incidence seen in lhBF.
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6.0
British Athletics Muscle Injury Classification System
The categorisation of hamstring injuries has an important role to play in identifying those
injuries that may require specific prevention or management strategies, have different time to return to training or re-injury rates. Classification refers to the categorisation of injury based on key
descriptive features and grading provides an indication of severity or extent of injury.
The British Athletics Muscle Injury Classification has classification as well as grading elements.
Injuries are classified (a, b or c) according to their anatomical site within the muscle and graded
(0–4) based on MRI indicators of injury extent, as shown in Figure 4. Injuries are classified as ‘a’
if they occur in the muscle or fascia, ‘b’ if they occur in the muscle-tendon junction or ‘c’ if they
occur within the tendon itself. The grading of injuries from 0 to 4 is based on the MRI measurements of cross-sectional area (CSA) and length of injury within the muscle or tendon, 0 being the
least damage, and 4 being the highest level of damage to tissue. The British Athletics classification
system has been demonstrated to have excellent inter-observer reliability rates and MRI parameters in hamstring injury have previously also been shown to demonstrate excellent reliability (Patel
et al, 2015). The British Athletics Muscle Injury Classification system will be adopted by Welsh
Athletics when referring to and diagnosing injuries to the HMC.
Figure 4. The British Athletics Muscle injury Classification System.
7.0
Return to Training Following Hamstring Injury
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Pollock et al (2015) reported that Grade 0 injuries were associated with a shorter time to return
to full training (TRFT) than any of the other injury grades. There was a significant difference
within the British Athletics Muscle Injury Classifications 1a–3c for TRFT. Analysis of grade and site
demonstrated that grade 3 severity and intratendinous (c) site were associated with an increase
in the TRFT as shown in Figure 5. No significant differences in TRFT were found between grades 1
and 2 or between classifications (a) and (b). An awareness of this is important to understand and
appreciate that the type c injuries and higher grade injuries require a longer time for healing and
subsequent rehabilitation.
7.1
Re-injury
There was a significant difference within the British Athletics classifications 1a-3c with respect to
injury recurrence. Analysis of grade and site suggested that grade was not associated with recurrence but that intratendon injuries (c) were associated with a higher risk of recurrence. This
significantly increased repeat injury rate was 63% in 2c injuries and 57% in 3c injuries. In comparison, the repeat injury rate in 2b injuries was only 6% and there were no recurrences in any myofascial (a) injury class
Figure 5. A Table to show the average time to return to full training in days in different British
Athletics Muscle injury classifications.
As part of this strategy, Welsh Athletics will provide guidance to coaches, athletes, and therapists
on the appropriate management of acute hamstring injuries through the stages of healing. A
sample of the reference documents produced can be found in Appendix B. The Welsh Athletics
Injury Audit will be used to inform coaches of high risk periods of the season where hamstring
injury incidence is high.
Coaches, athletes and therapists will be encouraged to chart progression objectively through the
rehabilitation process to more accurately direct return to training times. This will be guided by
Welsh Athletics as required by coaches, with a graded and objective return to sprinting protocol
advised.
For this to be successful, coaches, athletes and therapists will be encouraged to regularly screen
for movement deficiencies, muscle patterning, ranges of movement, strength and speed norms to
highlight any risk factors for hamstring injury, but also provide objective data for comparison in
the rehabilitation process should a hamstring injury occur.
8.0
Risk Factors for Hamstring Injury
Previous Injury
It is widely acknowledged that one of the greatest risk factors for injury is previous injury.History of previous injury to a particular muscle, is the single greatest risk factor for future
injury (Frekleton & Pizzari, 2013).
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Self Reporting Risk Factors
Low back pain/stiffness
Hamstring DOMS/Stiffness/Pain/Misfiring
Prolonged sitting - travel/exam periods
Objective Risk Factors
Reduced Passive Straight Leg Raise or Active Knee Extension test
Hamstring pain on contraction/resisted testing
Reduced Spinal movement
Reduced hip Internal Rotation
Other Risk Factors
Age is a significant risk factor for injury, with athletes of older age tending to be at increased
risk of sustaining a hamstring injury
Fatigue
Dehydration
9.0
How will the aims of the strategy be delivered/achieved?
The main aims of this strategy will be achieved through a systematic education process to
coaches, athletes, and therapists. All geographical areas within Wales will be covered with
specific event groups targeted through existing channels of education.
Presentations to coaches, athletes and therapists will be made at existing opportunities such as;
• National Development Programme Days
• National Performance Programme Days
• Round Table meetings
• Coach Education seminars
• 1:1 trackside sessions
Electronic presentations will be made to relevant groups with copies of presentations made available as resources, accessible for all. Education material will backed up and accompanied by a
series of podcasts reflecting the main areas of focus.
Specific workshops on injury prevention programs will be arranged with coaches working with high
risk athletes incorporating aspects (e.g. lower extremity postures, muscle lengths, contraction
type) that are most similar to the conditions associated with injury, such that the athlete can
optimise the gains in functional strength and minimise the risk of future injury.
9.1
3 Strand approach
Rather than delivering one large educational seminar to cover all aspects of hamstring anatomy,
mechanics, injury incidence and prevention, a 3 strand approach will be adopted to break
information down into relevant and topical sections.
The 3 main strands will take the form of;
Why? (Why are the hamstrings affected the way they are, and why do we have the need for such
strategies?)
• State of the nation - injury audit analysis
• Anatomy/Physiology and Mechanics
• Risk factors
What? (What happens when a hamstring muscle becomes injured, and what can we do to rehabilitate the injury and reduce re-injury risk?)
• Injury site & classification - implications for time loss
• Rehabilitation Guidelines/Principles
• Return to sprinting
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Where next? (Where are we able to make changes to potentially reduce the incidence of hamstring injuries?)
• Injury prevention through physical preparation - ROM, Strength, technical cuing and postural
set
10.0 How will the effectiveness of the strategy be measured?
The main aims of this strategy will be measured through analysis of the Welsh Athletics injury
audit of funded athletes. A reduction in hamstring injury incidence, a reduction in time loss from
injury (training and competition) and a reduction in hamstring injury recurrence in this population
being regarded as success of this strategy.
Less formal success will be gleaned from formal and informal feedback from coaches, athletes
and therapists using the educational resources made available.
11.0
Reference Tools
P.Ol.I.C.E Guidelines for the management of acute soft tissue injury www.physiosinsport.org
British Athletics Hamstring Injuries Video - https://youtu.be/VdPQvwktMOY
12.0
References
Alonso J., Edouard P., Fischetto G., Adams B., Depiesse P., and Mountjoy M. (2012)
Determination of future prevention strategies in elite track and field: analysis of Daegu 2011
IAAF Championships Injuries and illness surveillance
British Journal of Sports Medicine 46(7): 505 - 514
Askling C., Tengvar M., Saartok T., and Thorstensson A. (2007)
Acute first-time hamstring strains during high-speed running: a longitudinal study including clinical and magnetic resonance imaging findings
American Journal of Sports Medicine 35(2):197- 206.
Freckleton G., and Pizzari T. (2013)
Risk factors for hamstring muscle strain injury in sport: a systematic review and meta-analysis
British Journal of Sports Medicine 47: 351 - 358
Linklater J., Hamilton B., Carmichael J., Orchard J., and Wood D. (2010)
Hamstring Injuries: Anatomy, Imaging, and Intervention
Seminars in Musculoskeletal Radiology 14(2): 131 - 161
Patel A., Chakraverty J., Pollock N., Chakraverty R., Suokas A., and James S. (2015)
British Athletics muscle injury classification: a reliability study for a new grading system
Clinical Radiology 70: 1414 - 1420
Pollock N., Patel A., Chakraverty J., Suokas A., James S., and Chakraverty R. (2015)
Time to return to full training is delayed and recurrence rate is higher in intratendinous (‘c’) acute
hamstring injury in elite track and field athletes: clinical application of the British Athletics Muscle Injury Classification
British Journal of Sports Medicine 0: 1 - 6
Schache A., Dorn T., Blanch P., Brown N., and Pandy M. (2012)
Mechanics of the Human Hamstring Muscles during Sprinting
Medicine and Science in Sports and Exercise 44(4): 647-58
Van der Made A., Wieldraaijer T., Kerkhoffs G., Kleipool R., Engebretsen L., van Dijk C., and
Golanó P. (2015)
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The Hamstring Muscle Complex
Knee Surgery, Sports Traumatology, Arthroscopy 23: 2115 - 2122
Appendix A
Detailed Anatomy of the Hamstring Muscle Complex
The three hamstring muscles originate in close proximity to one another from the ischial tuberosity. An oblique ridge divides the hamstring origin into upper/lateral and lower/medial surfaces.
The upper/lateral area forms the origin for the semimembranosus tendon and is crescent shaped,
extending superoinferiorly over 3cm and transversely over 1cm. The lower/medial aspect gives
rise to the conjoint tendon of semitendinosus and biceps femoris, also situated more posteriorly,
and oval in shape with average measurements of 2.7 cm superoinferior and 1.8 cm transversely.
A significant portion of the semitendinosus muscle arises directly from the ischial tuberosity, medial to the conjoint tendon as shown in Figure 1 (Linklater et al, 2010).
The sacrotuberous ligament inserts onto the posterior margin of the conjoint origin of semitendinosus and biceps femoris and directly onto the ischial tuberosity, anatomically linking it with the
conjoint tendon origin.
Figure 1. Schematic (a) and cadaveric (b) images of the proximal hamstring complex origin.
(a)
(b)
SMB has the longest proximal tendon of the hamstrings, measuring an average of 31.9 cm (Linklater
et al, 2010). The SMB muscle belly extends over 26 cm and has the largest cross-sectional area of
the hamstring muscles with a mean area of 15.7 cm, giving it the maximal potential for force
generation out of the hamstring muscle complex, but the lowest velocity of fascicle shortening.
The distal tendon of SMB is relatively thick and broad in it insertional aspect. The mean length of
the distal tendon is 26.1 cm. The distal insertion of the SMB is primarily on the medial tibial
condyle posteriorly with expansions onto the posterior oblique ligament, posterior capsule, and
arcuate ligament, and in 50% of cases onto the periphery of the posterior horn of the lateral
meniscus.
The conjoint semitendinosus-biceps femoris (ST-BF) tendon extends for an average of 9.9 cm before separate biceps femoris and semitendinosus tendons become evident. The semitendinosus
muscle belly extends longitudinally over 31.6 cm with a mean total cross-sectional area of 8cm.
It lies posterior to the tendon of semimembranosus and becomes tendinous about halfway down
the thigh. The mean length of the proximal ST tendon is 12.9 cm, with often no clearly definable
tendon separate to the conjoint ST-BF tendon. The proximal MTJ is also relatively short, with a
mean length of 11.7 cm. The ST has a complex tendinous inscription on the surface of the muscle
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that divides the muscle into superior and inferior regions that are innervated by separate branches
of the tibial nerve. It has been speculated that the proximal and distal segments of the ST muscle
have some specificity of action on the hip and knee, respectively. The distal ST tendon is long and
thin, with a mean length of 25 cm, the distal MTJ extending over a mean of 13.9 cm. The distal
11 cm of the tendon has no muscle fascicles inserting into it. The distal insertion is via the pes
anserinus on the medial border of the proximal tibial shaft.
The proximal tendon of the long head of biceps femoris (lhBF) is relatively long, with a mean
length of 27.1 cm, including the conjoint ST-BF component. The lhBF muscle extends longitudinally over 28 cm and has a mean cross-sectional area of 10 cm. The distal tendon of lhBF is the
longest of the HMC, with a mean length of 27.5 cm. It is considered that the the proximal and
distal tendons of lhBF overlap as seen in Figure 2. This may be a feature that predisposes it to
greater injury risk than the other two muscles of the hamstring muscle complex. The ventral
portion of the distal tendon serves as the insertion site of the short head biceps femoris (shBF)
muscle. The distal lhBF tendon inserts in variable proportion onto the fibular head just lateral to
the styloid process, lateral condyle of the tibia, and the lateral fascia of the leg. The shBF arises
from the linea aspera below the gluteus maximus insertion, from the upper part of the lateral
supracondylar line of the femur and from the lateral intermuscular septum. The average muscle
length is 25.8 cm, with a total cross-sectional area of 3 cm. The distal insertion of the shBF is into
the distal tendon of lhBF, the fibular head, lateral tibial condyle, posterolateral capsule, and
capsule-osseous layer of the iliotibial tract.
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Appendix B
Guideline for hamstring injury rehabilitation through the stages of healing
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