Download Stevens, Ryan

CARDIFF SCHOOL OF SPORT
DEGREE OF BACHELOR OF SCIENCE
(HONOURS)
SPORT AND EXERCISE SCIENCE
TITLE
The comparison of muscle activation levels between a conventional bench press
without and with the use of a bench press block
NAME
Ryan Stevens
UNIVERSITY NUMBER
ST09001736
Contents
Page Number
ACKNOWLEDGEMENTS
ABSTRACT
Chapter One
1.0 INTRODUCTION
1
Chapter Two
2.0 LITERATURE REVIEW
2.1 Muscle activation between a conventional bench press and using the
bench press block
3
2.2 EMG
5
2.3 Factors affecting EMG
6
2.4 Reliability of EMG
8
2.5 Myoelectric cross talk
10
2.6 Importance of normalising EMG data
2.7 Aims and Hypotheses of the study
12
Chapter Three
3.0 METHODOLOGY
3.1 Participants
13
3.2 Experimental procedure
13
3.3 Familiarisation and pilot testing
14
3.4 Exercise descriptions
15
3.5 EMG
16
3.6 Statistical analysis
17
Chapter Four
4.0 RESULTS
4.1 EMG results
18
Chapter Five
5.0 DISCUSSION
References
Appendices
Participation information sheet
Questionnaire
Participation consent form
22
ACKNOWLEDGEMENTS
The author would like to show his appreciation to the following people:
To my dissertation supervisor Dr. Joseph Esformes, thank you for your support,
interest and valuable feedback throughout the process. Your time and effort has
been much appreciated and very beneficial.
To all of the 12 participants whom voluntary gave up their time to take part in the
present study. Your time was much appreciated as without your participation the
study would not have taken place.
To the physiology lab technicians Danny Newcombe and Mike Stembridge, for
arranging set timeslots for the testing to take place and providing me with the
knowledge needed to use the equipment. As well as this, I would like to show my
appreciation to Dr. Jon Oliver for aiding myself in the process of normalising the raw
data.
ABSTRACT
Introduction. The bench press exercise is what most people use to measure their strength
by. The sticking point in the bench press is a common area where failed attempts in the
bench press exercise may occur. This is due to the lack of activation from one set of
muscles to another. Many methods have been investigated to improve the bench press apart
from the use of bench press blocks. A bench press block is placed on an individual’s chest
performing the exercise to reduce the range of motion to train the activation of muscles
through the sticking point. To the author’s knowledge, at present, no study has compared
the muscle activation levels of a bench press without and with the use of a bench press
block. This would enable the identification of which of the prime movers were most dominant
at each phase of the bench press exercise. Methods. 12 undergraduate students (age, 20.4
± 0.8years; mass, 85.5kg ± 7.9kg; height, 1.76m ± 0.05m) took part in the study. Average
bench press experience was 3 years ± 1.1years. Each individual performed the bench press
without the block followed by using the block at 90% of their 1RM (one repetition max) for
one repetition only. All muscles investigated were collected using surface EMG
(electromyography). All signals were normalised in Microsoft Excel (Microsoft, USA) using a
rolling 25ms average. Results. The biceps brachii (BB), posterior deltoid (PD) and the tricep
brachii (TB) all showed significant differences (p<0.05) with the greatest peak amplitudes
being generated without the bench press block for the BB and PD (BB=1061.6mV ± 595.8;
PD= 441.9mV ± 314.5). However, the TB generated the greatest peak amplitudes with the
bench press block (TB= 2040.7mV ± 977.4). Conversely, the anterior deltoid (AD) and
pectoralis major (PM) showed no significant differences (p>0.05) (AD= without block
2233.6mV ± 736, with block 2231.1mV ± 791.5; PM= without block 2277mV ± 1826.6, with
block 192.5mV ± 179.6). Discussion. The AD and PM can be considered an agonist pair
and are vitally important throughout the whole lift in the bench press exercise. The BB and
PD are at their peak activation at the end of the eccentric phase without the use of the bench
press block. At this point, they are both contracted concentrically as flexion is at its greatest.
The peak activation of the TB was with the use of the bench press block. It was suggested
that the dramatic change in the TB considering the PM remained constant was due to the
fact that the TB has stabilization demands at both the elbow and the shoulder. Conclusion.
In conclusion, the sticking point may be caused by the delay in activation of the TB and/or
inability to sustain activation of the AD and PM. Therefore, isolation exercises to improve the
activation of the TB and sustain activation of the AD and PM will be of interest to those
coaches and athletes looking to improve bench press performance.
CHAPTER I
INTRODUCTION
1.0 INTRODUCTION
The bench press exercise is a multi-joint exercise that is normally used for ubiquitous
strength for the muscles involved in the pressing actions of the upper body amongst
recreational and performance athletes (Lehman, 2005).The bench press exercise
tends to be the most familiar of the resistance training exercises used from the elite
athletes to the recreational gym users as it provides a great turnover too many sports
and daily activities encountered (Richards and Dawson, 2009). For these reasons,
the bench press seems to be the most popular lift in the gym and an exercise that is
vital for strength training of the upper body (Barnett et al., 1995). In fact, the bench
press is a frequently used measure of upper body strength (Hyson, 2010).
The bench press lift is typically performed lying flat on a bench in a supine position
(Van Den Tillar and Ettema, 2010). The lifter is firstly required to lower the bar to the
chest (eccentric contraction) before pushing the bar back to the starting position
(concentric phase) (McLaughlin and Madsen, 1984). A successful bench press is
classified when the bar reaches a fully extended position. Similarly, the weight being
attempted may be greater than the force an individual is able to produce, the
individual may not be able to bring the bar to full extension which will result in a fail
(Van Den Tillar and Ettema, 2010).
A popular phase in the bench press that may enhance the chances of a failure is the
sticking point. This is referred to as the point in the range of motion during the bench
press where the upward movement of the barbell slows down or can even pause for
a small period of time (McLaughlin, 1984). This can also be referred to as the local
minimum of the upward velocity (Tvmin) (Madsen and McLaughlin, 1984). The sticking
point starts at 0.2 seconds from the moment the barbell is pushed off the chest and
can last up to one second thereafter (Van Den Tillar and Ettema, 2010) when using
loading intensities of ≥90% of 1RM (one repetition maximum) (Elliott et al., 1989).
Previous research has suggested that the occurrence of the sticking point during the
bench press exercise is due to the delay in the change from one set of activated
muscles to another (Elliot et al., 1989; Wilson et al., 1989). Much of the research has
compared different levels of EMG amplitudes between different methods and
exercises aimed at developing the bench press and the prime movers involved in the
bench press exercise (Schick et al., 2010; Lander et al., 1985; McCaw and Friday,
1
1994; Sandler 2006; Elliot et al., 1989). However, activation levels of the prime
movers in the bench press at each phase of the lift have still not been examined.
A more recent method of improving the bench press is to use a bench press block.
This aims to enhance improvement at the sticking point in the bench press lift. This
method involves placing a bench press block on the chest of the individual
performing the bench press. This enables the range of motion to be reduced so that
the individual will only lower the bar to the block where the start of the sticking point
occurs before pushing the bar back upwards to the starting position.
The implementation of the bench press block may enhance muscle activation at the
sticking point. Thus, reducing the effects of the sticking point by maintaining the
upward velocity of the barbell. Therefore, increasing the chances of a successful lift.
As well as this, it will allow the identification of the muscles that are involved in the
delay in activation causing the sticking point. A method that can be used to identify
levels of muscle activation is surface EMG (electromyography). EMG provides a
quantitative measurement of muscle activation by detecting, analysing and using the
electrical signal that is generated from contracting muscle (De Luca, 2006).
To the author’s knowledge, at present, no literature has examined the EMG
amplitudes between a conventional bench press without and with the use of a bench
press block. This will allow the identification of which muscles are most activated at
each phase in the bench press. As a consequence, identifying which muscles cause
the sticking point as a result of a delay in activation.
2
CHAPTER II
LITERATURE REVIEW
2.0 LITERATURE REVIEW
2.1 MUSCLE ACTIVATION BETWEEN A CONVENTIONAL BENCH PRESS AND
USING THE BENCH PRESS BLOCK
It has been established that the occurrence of the sticking point is due to the delay in
activation of one set of muscles to another (Elliott et al., 1989; Wilson et al., 1989)
and can be a vulnerable part of the bench press exercise that induces a failed
attempt. Therefore, muscle activation in the bench press is vitally important. Many
methods have been designed to develop strength in the bench press which may
prevent the decrease in velocity during the concentric phase of the bench press
exercise. Thus, if the velocity is maintained, it may enhance the chances of
completing the lift by reducing the effect of the sticking point.
It is stated that when developing maximal strength, training intensity is the essential
training variable to consider in strength athletes (Hakkinen et al., 1988; Hakkinen et
al., 1987; and Tan, 1999). The traditional method of developing strength is using a
heavy load and low repetitions (Baechle and Earle, 2008). Several studies have
shown that loads between 80-100% of 1RM are the most effective in developing
strength (American College of Sport Medicine, 2002). This is because working in
these loading ranges appears to recruit the muscle fibres at a maximum and produce
further neural adaptations (Hakkinen et al., 1985). Experienced weight training
athletes and weightlifters tend to use loads >90% of 1RM (Chestnaut and Docherty,
1999) because these loads have been shown to bring about optimum strength gains
most effectively. Hakkinen et al. (1987) support this by stating that they found an
increase 1RM in weightlifters performance when performing repetitions at an
intensity of 80-100%.
Another method used to increase the 1RM in the bench press exercise is to use
eccentric loading (Brandenburg and Docherty, 2002). Brandenburg and Docherty,
(2002) suggest that resistance training employing eccentric loading improves the
concentric 1RM of the elbow extensors which are used in the concentric phase of the
bench press exercise. Previous research has also shown that using 105% of 1RM of
concentric bench press in the eccentric phase of the lift and 100% of 1RM in the
concentric phase of the bench press increases the weight that can be lifted on the
successive concentric phase, and therefore, 1RM performance (Doan et al., 2002). A
3
possible mechanism for this is that eccentric loading creates cross bridges in
preparation for the concentric phase of the lift as the prime movers get into an active
state and force (Bobbert et al., 1996). This allows for greater joint moments and
therefore greater force production which allows heavier loads to be lifted (Bobbert et
al., 1996).
A further method that is recognised in increasing the bench press is by using
variable resistance. Variable resistance is a built in mechanism that provides varying
external resistances based on the muscle generating force capacity throughout the
full range of motion (Manning et al., 1990). Variable resistance usually comes in the
form of elastic bands or steel chains. Research has shown that variable resistance
increases muscle strength in the bench press (Bellar et al., 2011). This is used so
that individuals are lifting more weight where they are at their strongest phase during
the bench press and less weight where they are weakest. Therefore, as the
resistance varies throughout the full range of motion, it results in a degree of
synchronization of motor units (Aboodarda et al., 2011).
A more recent method is to incorporate the use of bench blocks, a training method
designed to train the sticking point which is caused by a lack of muscle activation
from one set of muscles to another (Elliot et al., 1989; Wilson et al., 1989). The
implementation of the bench press block may enhance muscle activation at the
sticking point. Therefore, reducing the negative effects of the sticking point
increasing the chances of completing the bench press lift. To the author’s
knowledge, at present, this is the first study comparing muscle activation levels
between a conventional bench press without and with the use of a bench press
block. This will allow the identification of which muscles are most activated at each
different phase in the bench press. As a consequence, identifying which muscles
cause the sticking point as a result of a delay in activation.
Previous research has compared the muscle activation levels between a free weight
bench press and a bench press using a smith’ machine (Schick et al., 2010). It was
found that the medial deltoid was more activated using the free weights bench press
and these occurred at loads of 90% of 1RM than that at 70% of 1RM (Schick et al.,
2010). Lander et al. (1985) and McCaw and Friday (1994) also support these
findings. These stated that the muscles in the shoulder are activated more during a
4
free weights bench press compared to a bench press performed on a Smith’
machine. A plausible explanation is suggested by Schick et al. (2010) stating that
there is less work for the synergist muscles with the smith’ machine bench press.
This could be due to the fact that the actual machine provides support during a
smith’ machine bench press which results in the shoulder muscles not having to
work as hard compared to a free weight bench press where there is no support
available.
Research also compared the electrical activity in the upper and lower pectorals and
the frontal deltoids between barbell bench press and the dumbbell bench press
(Sandler, 2006). Results suggested that the upper pectorals and frontal deltoids
showed greater electrical activity in the barbell bench press where as the dumbbell
bench press targeted the lower pectorals to a larger extent. However, this study was
conducted with loading intensities of 75% of 1RM which from previous research, has
shown to be too low for a sticking point to occur (Schick et al., 2010). Therefore, the
transition of one set of activated muscles to another would not have been identifiable
as the weight was not set at relative intensities.
Elliot et al. (1989) investigated the movement of the joints and muscle activation
patterns of the prime movers in the bench press exercise. These have been stated
by Clemons and Aaron, (1997) as being the shoulder muscles, pectoralis major
(PM), biceps brachii (BB) and triceps brachii (TB). However, the information in this
study was very brief and did not break down the muscular activation patterns of the
prime movers at each phase in the bench press lift.
One method by which levels of muscle activation is quantified in the studies listed
above is through the use of surface EMG.
2.2 EMG
EMG is the discipline that deals with the detection, analysis and the use of electrical
signal that is generated from contracting muscle (De Luca, 2006). EMG can be
performed by placing electrodes on the skin or invasively within the muscle (Day,
2003). Surface EMG is normally the favoured method of measurement due to its
non-invasive aspect. Therefore, there is less risk and pain free to the participants.
Surface EMG involves the measuring of electrical signals that are associated with
5
contracting muscle (De Luca, 2006). These signals are generated by the flow of ions
across muscle fibre membranes that pass through dominant tissues which can then
be quantified by surface electrodes (De Luca, 2006).
2.3 FACTORS AFFECTING EMG
There are many factors that can affect the amplitude of the EMG signal. These have
been identified as fatigue, causative, intermediate and deterministic factors.
Muscle fatigue is recognised as a decline in the tension development during constant
stimulation (Dimitrova and Dimitrov, 2002) and has a recognised relationship with the
amplitude and duration of motor unit activation potentials (Maestu et al., 2006).
Sandercock et al. (1985) demonstrated an increase in the EMG signal with fatigue.
Hakkinen and Paavo, (1999) disagreed with these findings by suggesting that there
was no significant difference during fatigue. However, despite the controversy
between the results, they both have their limitations. Sandercock et al. (1985)
conducted their study on animals which lacks validity. Also, the study conducted by
Hakkinen and Paavo, (1999) looks at isometric contractions which lack specificity to
the purpose of the current study. Therefore, a study conducted by Glass and
Armstrong, (1997) indicated that fatigue resulted in an increase in the EMG signals
when performing different variations of the bench press exercise. As this is more
specific to the purpose of the current study, it is important to consider the fatigue of
participants when conducting the study to ensure reliable results.
The EMG signal can be affected by the grip width used in the bench press, training
load and intensity. Pearson et al. (2009) noted that such factors have to be kept the
same in order to make a comparative assessment of muscle activation under
different conditions. When performing the bench press, research literature has
suggested that the usual grip is in the range of 10 to 30cm outside the shoulder joint
(Wagner et al., 1992). Previous research has shown that different grip widths effects
muscle activity (Clemons and Aaron, 1997; Barnett et al., 1995). Both of these
studies showed conflicting results. Clemons and Aaron, (1997) suggests there is an
increase in muscle activation of all muscles as grip width is widened. On the other
hand, Barnett et al. (1995) had mixed results with some muscles being more
activated and others less activated as the grip width increases. For example, Barnett
et al. (1995) suggested that the triceps brachii muscle was more activated with a
6
narrow grip as opposed to a wide grip. A possible explanation for the difference in
results could be due to the fact that both studies used different loading intensities
which can affect the amplitude of the EMG signal for each muscle. Therefore, in
order for reliability and validity of the study, each subject will perform the bench
press without and with the bench press block using a grip of 1.5 biacromnial width as
this appears not to affect muscle activation patterns and reduce injury risk (Green
and Comfort, 2007). The training load will affect the amplitude of the EMG signal
because the heavier the load, the more motor units are needed to be recruited.
Hence, the muscles are working harder which will generate greater muscle activation
levels (De Luca, 1997). This has been shown by Elliot et al. (1989) who
demonstrated that the sticking point occurs at ≥ 90% of 1RM.
The sticking point in the bench press exercise has also been suggested as not being
the phase where all attempts in the bench press will be unsuccessful (Van Den Tillar
and Ettema, 2010). However, the reduction in velocity of the bar will obviously
influence a failure in the bench press. This is because the failure you experience
during the sticking point occurs because the individuals applied force against the
loaded bar is not greater than the amount of weight being attempted (Wilson et al.,
1989). As the sticking point is caused by the delay in switching from one set of
activated muscles to another (Elliot et al., 1989; Wilson et al., 1989), muscle
activation in the bench press exercise is vitally important.
Other factors that have been known to affect the EMG signal have been classified
into groups by De Luca, (1997). These are causative factors, intermediate factors
and deterministic factors. These are briefly described in this literature review, for
further information the reader is directed to the paper by De Luca, (1997).
Causative factors are those that have a fundamental effect on the signal. These can
either be extrinsic or intrinsic. Extrinsic causative factors are associated with the
location of where electrodes are situated (De Luca, 1997). McGill et al. (1996) found
that appropriately placed surface electrodes reflect the level of amplitude of active
muscles. Intrinsic causative factors are uncontrollable. They relate to the
characteristics of the muscle from an anatomical, physiological and biomechanical
point of view (De Luca, 1997). These may include the number of motor units being
recruited, the proportion of muscle fibre types. For example, fast twitch fibres have a
7
high fatigue rate due to its rapid production of lactic acid (McArdle, Katch and Katch,
2010) which has been shown to increase the amplitude of the EMG signal
(Sandercock et al., 1985; HÄkkinen and Paavo, 1999). Also, the position of active
fibres within a muscle in comparison with the surfaces in which the electrodes are
located (De Luca, 1997). This can determine the spatial filtering and the amplitude
and frequency characteristics of the detected signal (De Luca, 1997). The
intermediate factors represent the physical and physiological phenomena which are
influenced by one or several causative factors (De Luca, 1997). Such intermediate
factors include the volume of electrodes that determine the strength of the signal as
it dictates the quantity of motor unit action potentials, the rate at which the action
potentials conduct which have a direct affect on the amplitude and frequency of the
signal and myoelectric cross talk (De Luca, 1997). Myoelectric cross talk is
discussed in further detail at the latter parts of the literature review. Finally,
deterministic factors are those that have an immediate impact on the EMG signal
with regards to its information and force amplitudes produced (De Luca, 1997).
Deterministic factors may include the number of active motor units, the pool of motor
units detected and the length, amplitude and nature of motor unit action potentials
(De Luca, 1997).
2.4 RELIABILITY OF EMG
Surface EMG is a popular tool used for the assessment of the neuromuscular
system (English and Weeks, 1989; Hermens et al., 2000; Lowrey et al., 2003). With
regards to the reliability of EMG, De Luca, (2002) has identified two problems that
influence the reliability of the signal generated. The first of these concerns is the ratio
between the energy in the EMG signal and the energy in the noise signal created by
the external environment. In order to increase the fidelity of the signal, maximising
the retrieval of information from the EMG signal with as minimal interference as
possible from the noise signal is desired (De Luca, 2002). There are two sources of
unwanted noise that can occur which are known as ambient and transducer noise.
Ambient noise is emitted from any device that is plugged into a socket where as
transducer noise is generated at the electrode-skin junction (Day, 2003). Many
methods have been used to try and reduce noise such as using conductive
electrolytes to improve contact with the skin, removing all hair and dead skin from
pre-arranged sites and using large surface areas (De Luca, 2002). However, there is
8
a consequent risk of increasing myoelectric cross talk. Hermens et al. (2002)
suggested the use of Ag-AgCl electrodes to reduce the impedance effects. The
second concern is the alteration of the EMG signal meaning that the frequency
component should remain the same (De Luca, 2002).
It is also established that fatigue can affect the reliability of the EMG signal (Glass
and Armstrong, 1997). Therefore, the participants will be restrained from upper body
exercise 24 hours prior to testing as this has been recognised as sufficient amount of
time to replenish the ATP/PC system (Bompa et al., 2002); the primary energy
system for explosive events lasting up to 10 seconds in duration (McArdle, Katch
and Katch, 2010).
Reliability is justified as the consistency of a device (Locono, 2004). Any new
measurement technique has to be examined for its reliability and validity (Locono,
2004). Regardless of the copious amounts of methods that have been developed to
measure reliability (Tyron, 1957; Hoyt, 1951), Test-retest procedure is considered
one of the most appropriate for EMG because it is the closest to the view of reliability
as a measure of consistency (Pedhazur et al., 1991). The length of measurement,
homogeneity of the objects being measured and the measurement interval are
factors that affect the test-retest method (Locono, 2004). With regards to the length
of measurement, the greater the amount of participants, the stronger its reliability.
With homogeneity of the objects being measured, the more homogeneity an object,
the less reliable it becomes. Finally, the measurement interval should not change the
object being measured. Thus, the object should remain constant at all times for
maximal reliability. However, it is impossible to consider the object to remain
constant no matter what the time between testing and retesting is. Slight alterations
may occur such as positional changes and placement of electrodes (Locono, 2004;
Mathur et al., 2005). This was demonstrated in a study conducted by Larson et al.
(2003) who conducted a study on the test-retest reliability of root mean squared
(RMS) and mean frequencey (MNF). Although the study showed good reliability, the
value of reliability was decreased due to the removal of the electrodes during the
interval time between the testing and retesting. This could be due to the fact that the
placement of electrodes may have been slightly different which could have given
different noise measurements between the two testing sessions resulting in a lower
reliability value.
9
2.5 MYOELECTRIC CROSS TALK
There are many advantages to EMG. A major advantage is the ability of the surface
electrodes to pick up large volumes (Lowrey et al., 2003). Thus, allows the
investigation of the activities of a variety of motor units. In contrast, there can be
unwanted signals generated from neighbouring muscles. This is known as cross talk
which has been identified by Lowrey et al. (2003) as a major limiting factor within
surface EMG. An effective method to reduce the susceptibility of cross talk is to
reduce the length and width of the detection surfaces. Larger electrodes are more
prone of detecting signals from adjacent muscles so situations of where this is a
concern could be overcome with the use of smaller electrodes (De Luca, 2002).
Cross talk can be influenced by many factors. Solomonow et al. (1994) identified
cross talk as an issue when conducting surface EMG on muscles surrounded with
copious amounts of subcutaneous adipose tissue. This is due to the fact that
subcutaneous fat and skin are anisotropic and act as a spatial filter (Day, 2003).
Thus, fewer signals can be measurable from distant electrical sources. Lindstrom
and Magnusson, (1997) states that cross talk can be avoided by decreasing the
distance of the inter-electrode that decreases the recording distance, which in turn,
shifts the EMG bandwidth to higher frequencies. Larsson et al. (2003) also identified
that surface EMG data can be tampered with if surface electrodes are not positioned
correctly. For example, near innervations zones or tendon locations.
Many methods have been designed to improve EMG data and also detect unwanted
signals. Cross talk can be estimated between two muscles by examining changes in
their electrical activity following a spontaneous effect in one of the muscles in
response to nerve stimulation (Mezzarane and Kohn, 2009). In this study, a reflex
compound muscle action potential was used to bring about a silent time phase in the
muscle that causes cross talk. Therefore, if a target muscle is picking up muscle
activity from other sources, a silent period would be observed in the electromyogram
of the distant muscle simultaneously with a decrease in the EMG of the targeted
muscle (Mezzarane and Kohn, 2009).
Farina et al. (2004) also identifies that cross talk are non-propagating signal
components, generated by the extinction of the intracellular action potentials at the
tendons. Therefore, cross talk has different shape signals in comparison to those of
10
active muscles. Thus, methods to reduce cross talk such as cross-correlation
coefficient and high-pass temporal filtering are not reliable (Farina et al., 2004). In
turn, detection systems used must be discussed separately with regards to
propagating and non-propagating signal components.
A more recent study by Vieira et al. (2010) incorporated bi-dimensional grids (8 rows
and 15 columns) of surface electrodes in order to improve the accuracy of EMG
data. Grayscale images were created from EMG data, filtered then segmented into
clusters of activity with the watershed algorithm. The results indicated that segment
accuracy was 60% and increased substantially to 95% when pixels below an
intensity of 70% of maximal EMG amplitude in each segment were not included
(Vieira et al., 2010). Therefore, the segmentation method is ideal for such studies
who want to automatically track specific skeletal muscle activity.
2.6 IMPORTANCE OF NORMALISING EMG DATA
EMG normalisation is a prerequisite for an analysis of comparing EMG signals
(Mathiassen et al., 1995). Normalisation is a method that can help with comparing
electrode sites of a muscle, on different muscles and a change over a period of time
(Lehman & McGill, 1999). Normalisation is the process by which muscle activity is
expressed as a percentage from millivolts (Lehman & McGill, 1999). However, as the
voltage of surface EMG depends on factors varying between individuals and the
course of time in which it is distributed, Mathiassen, (1997) considers the amplitude
of surface EMG unnecesary in group comparisons or following events over a
prolonged time period. Gerdle et al. (1999) explains the importance for normalisation
of surface EMG with the fact that all EMG recorded is never absolute. Possible
reasons for this are due to the variations in impedance of active muscle fibres and
electrodes. Thus, gives an important value to normalising data when comparing
amplitude variables between measurements. A popular technique of normalisation is
converting the signal amplitude with regards to force or torque (Day, 2003).
Therefore, making it useful to all measurement occasions. For example, relating the
EMG to maximal voluntary contraction (MVC), sub maximal contractions or reference
voluntary contractions (RVC) (Lehman and McGill, 1999; Day, 2003). For other
examples of normalisation techniques, the reader is directed to the papers by
Mathiassen et al. (1995, 1997) and Merletti et al. (1995). Using peak and average
11
normalised data will allow for the results of the study to have a greater reliability
value.
2.7 AIMS AND HYPOTHESES OF THE STUDY
The research at present has identified the prime movers in the bench press, the
cause of the sticking point and loading intensities at which these occur. A copious
amount of comparative research has been conducted on muscle activation involving
the prime movers in the bench press. However, there is no research, to the author’s
knowledge, at present that compares muscle activation using bench press blocks.
Also, there is no research that suggests which of the prime movers are most
activated during each phase of the bench press exercise.
Therefore, due to the lack of research, the author fails to hypothesise about the
study. However, the aim of the study is a twofold. The first aim is to compare the
muscle activation levels of the prime movers in the bench press exercise without and
with the use of a bench press block. This will allow the investigation of the second
aim, the identification of the muscles that are most activated at each phase of the
bench press exercise, indicating what muscles are delayed in activation causing the
sticking point to occur.
12
CHAPTER III
METHODOLOGY
3.0 METHODOLOGY
3.1 PARTICIPANTS
12 undergraduate male students (age, 20.4 ± 0.8years; mass, 85.5kg ± 7.9kg;
height, 1.76m ± 0.05m) studying at the University of Wales Institute Cardiff (UWIC)
were recruited for the study. The students were chosen based on the criteria needed
to participate in the study. The criteria needed to participate in the study was to have
had at least one years experience in the bench press exercise. The average bench
press experience of the group was 3 years ± 1.1years. All participants chose to
participate in the study on their own accord. They were fully aware of what was
expected of them from the participant information sheet they received with the
questionnaire. All participants were then required to sign an informed consent sheet.
Ethical approval was granted by the UWIC Ethics Committee in order for the study to
commence. For examples of all forms please see appendices. All subjects were
prohibited from upper body exercise for 24 hours prior to testing to ensure full
restoration of ATP/PC (Bompa et al., 2002). This will also ensure the participants are
not fatigued, which has been shown to influence the amplitude of the EMG signal
(Glass and Armstrong, 1997).
3.2 EXPERIMENTAL PROCEDURE
Each participant was required to attend one session. The load was already placed
on the bar at 90% of the individuals 1RM which had been previously calculated from
the familiarisation session. Prior to the testing, each individual had their stature
measured using a stadiometer (Model Holtain, Holtain Ltd, Crymych, Wales) and
mass was obtained using an electronic set of weighing scales (Model 770, SECA,
Vogel and Halke, Hamburg, Germany). Continually, all individuals were sustained to
a warm up of 10 repetitions maximum on the bench press and upper body stretches.
Following on from the warm up, surface electrodes (H59P, Tyco healthcare group,
MA, USA) and multi channel wires were attached to each individual at the prearranged sites which were secured with electrical tape. The individual was then
required to get into position whilst a grip of 1.5 biacromnial width was measured for
the individual using a tape measure. Subjects were required to perform a
conventional bench press followed by a bench press incorporating the use of a
13
bench press block with the same load on the bar. The repetition was completed in 5
seconds, broken down into 2 seconds for the eccentric and 3 seconds for the
concentric phase. The concentric phase was given an extra 1 second to take into
account the decrease in velocity of the barbell when pushing through the sticking
point. The total time frame given to participants to complete each contraction was 12
seconds. The additional time was added so that participants did not feel rushed to
perform the lift so they had time to fully prepare themselves as it was near maximal
lifts taking place. Trials that did not need the additional time were cropped to 5
seconds.
This was normalised using an electronic metronome. The load was calculated to the
nearest 2.5kg for 90% of the participants 1RM because 1.25kg were the smallest
weight plates available (1.25kg each side of the bar equals 2.5kg). For example,
90% of a participant 1RM was calculated at 138kg, thus 137.5kg was implemented
as the test weight. Participants were allocated 2 minute rest between each lift which
was
monitored
using
a
stopwatch
(Fastime
5
Dual,
display
stopwatch,
Leicestershire, England). Participants were allocated 2 minute rest periods as this is
sufficient amount of time to restore ATP/PC stores (Richmond and Goddard, 2004).
3.3 FAMILIARISATION AND PILOT TESTING
A pilot session was arranged four weeks prior to actual testing with one of the
participants. The aim of this session was to elevate the researcher’s confidence with
using the equipment and solve any issues that arose before actual testing starts. A
major issue that was addressed was the movement of electrodes and wires during
the bench press exercise which were affecting the electromyogram. This was
overcome by securing the electrodes and wires with electrical tape. Also, as the
process of testing was perceived time consuming, it was suggested that all
participants would be tested individually to prevent time wasting of the other
participants.
Two weeks prior to actual testing, all participants were then required to attend a
familiarisation session. This session was to confirm with participants of the
procedures that were going to take place, familiarise themselves with the apparatus
and to identify their 1RM lifts so that relative loads could be calculated in preparation
14
for actual testing. This allowed the actual testing sessions to run more effectively and
efficiently.
3.4 EXERCISE DESCRIPTIONS
The bench press: Each participant took a lying supine position on the bench press
where a natural lordotic curve was evident and feet were firmly placed on the floor. A
firm overhand grip was used with a grip of 1.5 biacromnial width to prevent injury.
The movement was initiated with flexion at the elbow until the bar touched the chest
before pressing the bar back up to its original starting position. It was compulsory for
the back, feet and head to remain firm and in contact at all times.
The bench press block: The same procedures applied with the use of the bench
press block. However, the bar was only brought down until it made contact with the
block before being pressed back up to its original starting position. The bench press
block was designed based on the research by Van Den Tillar and Ettema, (2010)
who stated that the sticking point starts at 0.2 seconds after the barbell is pushed of
the chest.
Figure 1. Visual representations of the variations of the bench press exercise performed in
this study
15
3.5 EMG
An 8 channel EMG recorder was used in the process of collecting the muscle activity
of the prime movers in the bench press (Mega ME600, Mega Electronics, Kuopio,
Finland). Signals were monitored by the software Megawin 1.2 (Mega Electronics
Ltd, Finland) that was stored on a laptop computer. The laptop and EMG recorder
were connected via a fibre optic cable allowing the monitoring of generated signals.
EMG sampling rates were completed at a frequency of 1000Hz. Fridland and
Cacioppo, (1986) suggest that anything under 1000Hz comes with a danger of under
sampling and Durkin and Callaghan, (2005) suggested oversampling can take place
with frequencies over 1000Hz. Also, there was only very little significant difference
when comparing sampling rates of 1000Hz and 2000Hz (Durkin and Callaghan,
2005). Therefore, a sampling rate of 1000Hz is deemed necessary.
EMG data was measured using the prime movers in the bench press. These were
indicated as being the muscles in the shoulder, pectoralis major, biceps brachii and
the triceps brachii (Clemons and Aaron, 1997).
Bipolar Ag-AgCI surface electrodes were placed at the pre-arranged sites. They
were located as accurately as possible along the muscle bellies, parallel to the
underlying muscle fibres (Gouvali and Boudolos, 2005). Location of surface
electrodes on the muscle belly has been suggested as the easiest location to record
large surface EMG signals (Hermens, 2000). EMG signals were recorded at 5
locations: approximately 4cm below the clavicle for the anterior deltoid (AD) (Schick
et al., 2010), approximately 4cm below the acromion process for the posterior deltoid
(PD) (Schick et al., 2010), 4cm from the axillary fold for the pectoralis major (PM)
(Schick et al., 2010), middle of the muscle belly for the biceps brachii (BB) (Van,
1993) and half way between the olecranon and the acromion for the triceps brachii
(TB) (Gouvali and Boudolos, 2005). All electrodes were placed on the right side of
the body (Goodman et al., 2008).
Prior to the testing and preparation of electrodes, all hair was removed from prearranged sites, lightly sanded to remove dead skin followed by cleanse of alcohol to
improve conductivity of the EMG signal (Wahl and Behm, 2008). After skin
preparation, the identification of a light red colour to the skin shows good skin
impedance (Konrad, 2005). This allows for maximal recordings of EMG signals.
16
Ground electrodes were also located on inactive tissue/bony parts as required by
(Hermens et al., 2000). Hermens et al. (2000) suggested the wrist was a popular
location to use for the muscles in the arm and the sternum for the shoulder and
chest. Earth electrodes were placed on the clavicle for the AD and PD, the sternum
for the PM and the styloid process of the radius and ulna for the TB and BB.
However, each participant found it uncomfortable to fully extend their arms due to
the length of the wires. Therefore, earth electrodes for the TB and BB were relocated
to half way between the styloid process of the radius and ulna and the olecranon.
EMG signals were normalised in Microsoft Excel version 2007 (Microsoft, USA)
using a Rolling 25millisecond average. The raw data was inputted into an EMG
template in Microsoft Excel where the raw data was rectified giving each piece of
data its absolute value. This allowed the data to be processed as the data was
smoothed using a 25millisecond rolling average. Peak activation was located for
each muscle, in each participant, for each contraction from the processed channel.
An average was taken from the peak activation values for each muscle. This enabled
the identification of the maximal motor unit recruitment for each muscle in both
conditions.
3.6 STATISTICAL ANALYSIS
All peak EMG values for the five muscles were imported into the Statistical Package
for the Social Sciences (SPSS version 17 for windows, SPSS Inc., Chicago, IL)
where statistical analysis could take place. A paired sample t-test was used to
identify any differences within individuals for the muscles examined between the two
different conditions. All data was presented as peak value ± standard deviation,
unless stated otherwise. The level of significance was set at p<0.05.
17
CHAPTER IV
RESULTS
4.0 RESULTS
4.1 EMG RESULTS
Figure 2 and 3 gives examples of raw electromyograms for the bench press without
and with a bench press block. Figure 4 shows an electromyogram once the data has
been processed. The normalised peak EMG values for the bench press without and
with a bench press block are illustrated in figures 5 and 6. Table 1 examines the
normalised peak values for each muscle in both conditions.
The results indicate that the BB, PD and PM have higher peak activation levels when
performing the bench press without the bench press block. However, the TB
indicates higher muscle activation levels with the use of the bench press block. The
peak activation levels for the AD and PM appear to have not changed (see figure 5,
6 and table 1).
Figure 2. An example a raw electromyogram for the conventional bench press
exercise without the bench press block.
18
Figure 3. An example of a raw electromyogram for a conventional bench press with
the use of a bench press block.
Figure 4. An example of a raw electromyogram after a rolling 25millisecond
averaging had been applied to the TB muscle.
19
Peak Activation (mV)
Peak Activation Levels for a Conventional Bench
Press
4500
4000
3500
3000
2500
2000
1500
1000
500
0
BB
TB
AD
PD
PM
Muscle
Figure 5. Normalised peak activation levels for the 5 prime movers of the bench
press exercise without the bench press block.
Peak Activation (mV)
Peak Activation Levels for a Bench Press with a
Bench Press Block
3500
3000
2500
2000
1500
1000
500
0
BB
TB
AD
PD
PM
Muscle
Figure 6. Normalised peak activation levels for the 5 prime movers of the bench
press exercise with the use of a bench press block.
The outcome of the paired sample t-test indicated a significant difference for peak
activation levels for the BB, PD and TB (p<0.05). The BB and PD generated their
greatest peak amplitudes without the bench press block as oppose to the TB, which
generated the greatest peak amplitude with the use of the bench press block.
However, the AD and PM failed to show any significant difference as they generated
similar peak muscle activation levels under both conditions (p>0.05) (see table 1).
20
Table 1. Normalised peak activation levels for the 5 different muscle groups tested
for the bench press exercise without and with the bench press block.
Conditions
Bench Press Without Block
Bench Press With Block
Biceps Brachii
(BB)
Peak
1061.6 ± 595.8*
270.9 ± 72.9
Peak
1305.3 ± 789.3
2040.7 ± 977.4*
Peak
2233.6 ± 736
2231.1 ± 791.5
Peak
441.9 ± 314.5*
192.5 ± 179.6
Peak
2277 ± 1826.6
1757.4 ± 1564.1
Triceps Brachii
(TB)
Anterior Deltoid
(AD)
Posterior Deltoid
(PD)
Pectoralis Major
(PM)
*Significantly different ( p<0.05).
21
CHAPTER V
DISCUSSION
5.0 DISCUSSION
The aim of the study was to compare muscle activation levels of the bench press
exercise without and with the use of a bench press block. Thus, distinguishing which
of the prime movers in the bench press were most dominant at each phase of the lift.
Therefore, contributing to knowledge by identifying which of the prime movers in the
bench press play an important role in the transition through the period of the sticking
point. The results from the present study indicate that the sticking point will occur
due to the delay in activation of the TB. The AD and PM appeared to have no
significant differences but were highly activated in both conditions indicating that they
are both very important throughout the whole lift. As a result, the AD and PM have to
maintain their muscle activation level throughout the entire lift in order to induce a
successful lift. To the author’s knowledge, at present, this is the first study comparing
muscle activation levels between a bench press without and with the use of a bench
press block.
Results obtained from the present study were in agreement with findings of other
investigators of similar studies (Elliot et al., 1989, Ferreira et al., 2003a; 2003b and
Sadri et al., 2011). The two of the five muscles, the AD and PM act as primary motor
agonists and shoulder joint stabilizers during the movement (Ferreira et al., 2003a;
2003b). These actions are considered to occur at the same time suggesting them to
be an agonist pair (Sadri et al., 2011). This gives a plausible explanation to their
increased activation throughout the whole lift. Elliot et al. (1989) indicates both the
AD and PM are activated at the initial phase of the concentric movement and
continue their activation throughout. This is in agreement with the findings from the
current study as both were highly active throughout the movement with similar
activation levels. However, the margins between both muscles varied with the AD
being slightly greater during the bench press with the use of the bench press block.
This may have occurred as the reduced range of motion decreased the activation of
the PM; the primary motor agonist at horizontal flexion (90 degrees) (Sadri et al.,
2011).
Peak activation levels for the PD had the lowest amplitudes out of all the muscles
examined. The PD was significantly different giving the greatest peak muscle
activation level during the bench press without the use of the bench press block.
22
During the bench press exercise, the PD is contracted concentrically at the end of
the eccentric phase resulting in enhanced EMG amplitude (Scoville et al., 1997).
However, there is also slight activation from the PD in the bench press with the use
of the bench press block where the PD is not contracted as the range of motion is
reduced. This contradicts the research by Schick et al. (2010) that does not identify
the PD as a prime mover in the bench press. This may have occurred due to cross
talk of the electrodes with the medial deltoid; a stabilizing muscle in the bench press
exercise (Schick et al., 2010). Smaller electrodes could be used to prevent cross talk
of neighbouring muscles. However, at the same time the electrodes need to be big
enough to record an adequate amount of motor units (day, 2003).
It is important to note that although the BB is not seen as a primary agonist in the
concentric phase of the bench press (Schick et al., 2010), it produced EMG
amplitude which was significantly greater in the bench press exercise without the
bench press block. This could have occurred as the BB is the prime mover in elbow
flexion which would be restricted from occurring with the use of the bench press
block due to the decreased range of motion (Oliveira et al., 2009). Therefore, the BB
would have greater activation levels at the end of the eccentric phase in the bench
press where elbow flexion would be the greatest. This supports similar findings of
Beck et al. (2011) that clearly identify different EMG intensities between eccentric
and concentric contractions with accuracy rates up to 100%. Eccentric contractions
have been associated with higher rate of force production as oppose to concentric
contractions which would agree with the greater activation amplitudes of the BB
experienced without the bench press block and during the eccentric contraction
phase (McArdle, Katch and Katch, 2010). Also, the speed of control at which the
eccentric phase is carried out can generate greater muscle activations in the BB and
affect the subsequent concentric phase (Van Den Tillar and Ettema, 2010). Thus, the
muscles are under tension for longer periods of time generating greater muscle
activations. However, it is evident that the BB was still activated in the bench press
with the use of the bench press block. This could have occurred as although the
range of motion is reduced, there is still some flexion of the elbow taking place.
Peak activation of the TB was significantly greater in the bench press with the use of
the bench press block. Therefore, this suggests activation of the TB is vitally
important in the second phase of the bench press in order to complete the lift. The
23
increase in the TB with the use of the bench press block may have occurred due to
post activation potentiating induced from the previous bench press set without the
bench press block. Metzger et al. (1989) suggested this could improve muscle twitch
and rate of force development due to the increase in sensitivity of calcium in the
myofilaments. Another possible mechanism is the reflex potentiation that leads to an
increase in muscle response to an afferent neural volley (Iglesias-soleur et al.,
2011). As a result, increasing muscle responses for the lift with the bench press
block eliciting greater muscle activation levels.
The amplitude of the post activation potentiating is largely dependent on the
characteristics of the muscle, with the fibre type being the most important (Hamanda
et al., 2000). The larger the post activation potentiating in fast twitch muscle fibres is
related to their greater capacity of myosin regulatory light chain phosphorylation in
response to high frequency stimulation (Grange et al., 1993). However, post
activation potentiating has been shown to have no significant improvement in bench
press performance (Requena et al., 2005). This can be suggested as there is a
proposed link between fatigue and high stimulation frequencies indicating that
potentiating mechanisms and fatigue act simultaneously (Masiulis et al., 2008).
Therefore, it may not result in an improvement in bench press performance as the
muscles maybe fatigued instead of the excitement of the central nervous system.
However, still generating high levels of muscle activation as the muscles have to
work harder for any given intensity due to fatigue (Maestu et al., 2006). This may
have occurred in the present study as both conditions were completed on the same
day. This may give a plausible explanation for the large standard deviations
experienced in the results, as some of the participants may not have fully recovered
from the first set (without the bench press block) heading into the second set (with
the bench press block) fatigued.
Another thing to note is how the PM remained fairly consistent between the two
testing procedures compared to the TB which changed dramatically in the second
phase of the bench press. This is in accordance with similar findings of Lehman et al.
(2006) who investigated shoulder EMG during different variations of a push up on
different surfaces. Although this study does not match with the present study, the
same results were obtained. Lehman et al. (2006) provided a possible explanation
for the results by explaining the differences between the joints they cross and
24
movements they produce. The PM is a single joint muscle where as the TB muscle is
a two joint muscle. Therefore, the PM may only be concerned with its primary
movement, where as the TB has stability and movement demands at both the elbow
and shoulder resulting in such a dramatic change throughout the phases of the
bench press (Lehman et al., 2006).
Although the present study generated meaningful results, potential cross talk from
neighbouring muscles reduces the reliability of the results. This maybe in particular
with the PD detecting muscle activation of the medial deltoid; a stabilizing muscle in
the bench press exercise (Schick et al., 2010). Moreover, all electrodes remained
intact during testing which is known to affect the test-retest reliability method
(Locono, 2004; Marthur et al., 2005). Thus, increasing the studies reliability status.
Also, there is no set point in the current study that separates the eccentric phase
from the concentric phase of the bench press lift. Therefore, it is difficult to
distinguish when the contraction starts and ends. This could be improved by using
sensors that enable the identification of when a contraction starts and finishes. This
could lead to further improvements by using data integration to normalise the raw
data, which would enable the sum of all muscle activation levels over the course of
the contraction (Fridlund and Cacioppo, 1986). All participants in the study had a
minimum of one years experience in the bench press exercise. It is likely that
experience in resistance training such as the bench press will allow greater force
production to be produced as the prime movers are more likely to be developed in
the experienced lifters (Anderson and Behm, 2005). As a result, the findings cannot
be generalised to the general population. The sticking point was suggested to start at
0.2 seconds from the start of the concentric phase in the bench press exercise (Van
Den Tillar and Ettema, 2010). However, this may vary between individuals as it has
the potential to continue up to one second thereafter (Van Den Tillar and Ettema,
2010). This may have resulted in participants not reaching or pushing through their
sticking points when using the bench press block. Therefore, to ensure reliable
results, all sticking points could be individually analysed and bench press blocks
made specific to each individual.
The area of improvement identified in the present study has given potential options
for future research. Future research could conduct a similar study using needle
electrodes as oppose to surface EMG as it has the potential to improve the quality of
25
the signal generated (De Luca, 2006). However, this was not an option to
undergraduate students due to ethical reasons. Distinguishing between concentric
and eccentric muscle activity levels could be beneficial. Van Den Tillar and Ettema,
(2010) found that the greater control of the eccentric phase gave a larger muscle
activation in the BB and TB which may have had a transference on the muscle
activation level on the subsequent concentric phase. By distinguishing the muscle
activation levels between both, the concentric and eccentric phase can indicate more
accurate results for each of the individual muscles. As previously mentioned as a
limitation of the current study, the same study could also be repeated separating
both conditions by a period of 24 hours to ensure full recovery of all participants
(Bompa et al., 2002). This could reduce the standard deviations experienced in the
present study making the results more accurate and reliable. As previously stated,
the current study cannot be generalised to the general population. Anderson and
Behm, (2005) stated that neuromuscular adaptations associated with experience
lifters will improve muscle activation further. Thus, there is a possibility that different
results may be obtained if the same study was conducted with novice lifters. As a
result, a similar study should be designed as the study previously conducted and
applied to a range of homogenous groups. As a consequence, the study can then
start to be generalised to a wider population. The researcher purposely did not use
different homogenous groups in the present study as this would have decreased the
reliability status of the results (Locono, 2004). Future research could also conduct a
similar method and individualise each of the participant’s sticking points as this may
vary between individuals. Therefore, this would ensure all participants are pushing
through their sticking points when using the bench press block, creating more
accurate and reliable results. Lastly, a larger scale version of the current study could
be used because as previously mentioned, the larger the length of measurement, the
more reliable the results (Locono, 2004). Also, future research could conduct a
similar study including muscles that act as synergists to provide more in depth
knowledge of muscle activation in the bench press such as those of the rotator cuff
muscles (Schick et al., 2010).
In conclusion, suggestions can be made that the sticking point may occur due to the
delay in activation of the TB and/or failure to maintain muscle activation levels in the
AD and PM. The current research has not only challenged previous research and
26
contributed to current knowledge, but has given an incentive for future research to
expand knowledge further.
The knowledge gained from the current study may be of interest and apply to any
individual that coach and/or intend on improving bench press performance. To the
author’s knowledge, at present, no other study has compared the muscle activation
levels in the bench press exercise without and with the use of a bench press block.
Therefore, the present study can aid in indication of which muscles are dominant at
each phase in the bench press exercise. This can have practical implications in
improving bench press performance as the sticking point in a bench press exercise
has been previously mentioned to be due to the delay in activation of one set of
muscles to another (Elliot et al., 1989; Wilson et al., 1989). The current study can aid
in this situation by identifying which of the prime movers need to be developed to
prevent this from future occurrence. If an individual is experiencing failure at the
sticking point in a bench press, exercises to isolate the TB, sustain activation of the
AD and PM could be implemented.
27
REFERENCES
Aboodarda, S.J., George, J., Mokhtar, A.H., and Thompson, M. (2011). Muscle
strength and damage following two modes of variable resistance training. Journal of
Sports Science and Medicine, 10, 635-642.
American College of Sport Medicine. Position Stand: Progression models in
resistance training for healthy adults. Journal of Sports Medicine in Sport and
Exercise Science, 34(2), 364-380.
Anderson, K., and Behm, D.G. (2005). Trunk muscle activity increases with unstable
squat movements. Canadian Journal of Applied Physiology, 30, 33–45.
Baechle, T.R., Earle, R.W., and Wathens, D. (2008). Resistance training In T.
Baechle and R. Earle (Ed.), Essentials of Strength and Conditioning: National
Strength and Conditioning Association (pp. 401). USA: Human Kinetics.
Barnett, C., Kippers, V., And Turner, P. (1995). Effects of variation on the bench
press exercise on the EMG activity of five shoulder muscles. Journal of Strength and
Conditioning Research, 9, 222-227.
Beck, T.W., Stock, M.S., and DeFreitas, J.M. (2011). Paired pattern classification of
electromyographic intensity patterns during concentric and eccentric muscle actions.
Journal of Clinical Kinesiology, 76-77.
Bellar, D.M., Muller, M.D., Barkley, J.E., Chul-Ho, K., Ida, K., Edward, R.J., Bliss,
M.V., and Glickman, E.L. (2011). The effects of combined elastic and free weight
tension Vs free weight tension on one repetition maximum strength in the bench
press. Journal of Strength and Conditioning, 25(2), 459.
Bobbert, M.E., Gerritsen, K.G.M., IJtjens, M.C.A., and van Soest, A.J. (1996). Why
is countermovement jump height greater than squat jump height? Medicine and
Science in Sport and Exercise, 28(11), 1402-1412.
Bompa, T.O., Di pasquale, M., and Cornacchia, L.J. (2002)(2nd ed.). Serious strength
training. Champaigne, III: Human Kinetics.
Brandenburg, J.P., and Docherty, D. (2002). The effects of accentuated eccentric
loading on strength, muscle hypertrophy, and neural adaptations in trained
individuals. Journal of Strength and Conditioning Research, 16(1), 25-32.
Chestnaut, J.L., and Docherty, D. (1999). The effects of 4 and 10 repetition
maximum weight training protocols on neuromuscular adaptations in untrained men.
Journal of Strength and Conditioning Research, 14, 353-359.
Clemons, J.M., and Aaron, C. (1997). The effect of grip width on the myoelectrical
activity of the prime movers in the bench press. Journal of Strength and Conditioning
Research, 11(2), 82-87.
Day, S. (2003). Important factors in surface EMG measurement, [on-line].
http://www.bortec.ca/Images/pdf/EMG%20measurement%20and%20recording.pdf
[accessed 18th October 2011].
De Luca, C.J. (1997). The use of Surface Electromyography in biomechanics.
Journal of Applied Biomechanics, 13(2), 135-163.
De Luca, C.J. (2002). Surface electromyography: detecion and recording. Delsys
Incorporated, 1-10.
De Luca, C.J. (2006). Electromyography. Encyclopedia of Medical Devices and
Instrumention, 98-109.
Dimitrova, N.A., and Dimitrov, G.V. (2002). Amplitude related characteristics of motor
unit and M-wave potentials during fatigue. A simulation study using literature data on
intracellular potential changes found in vitro. Journal of Electromyography and
Kinesiology, 12(5), 339-349.
Doan, B.K., Newton, R.U., Marsit, J.L., Triplett-McBride, N., Koziris, L.P., Fry, A.C.,
and Kraemer, W.J. (2002). Effects of increased eccentric loading on bench press
1RM. Journal of Strength and Conditioning Research, 16(1), 9-13.
Durkin, J., and Callaghan, J.P. (2005). Effects of minimum sampling rate and signal
reconstruction on surface electromyographic signals. Journal of Electromyography
and Kinesiology, 15(5), 474-478.
Elliott, B.C., Wilson, G.J., and Kerr, G.K. (1989). A biomechanical analysis of the
sticking region in the bench press. Journal of Sports Medicine in Sport and Exercise
Science, 21, 450-462.
English, R.W., and Weeks, O.I. (1989).
Electromyographic cross-talk within a
compartmentalized muscle of the cat. Journal of Physiology, 416, 327-336.
Farina, D., Merletti, R., Indino, B., and Graven-Nielsen, T. (2004). Surface EMG
crosstalk evaluated from experimental recordings and simulated signals. Reflections
on crosstalk interpretation, quantification and reduction. Methods of Information in
Medicine, 43(1), 30-35.
Ferreira, M.I., Büll, M.L., & Vitti, M. (2003a). Electromyographic validation of basic
exercises for physical conditioning programmes. Analysis of the deltoid muscle
(anterior portion) and pectoralis major muscle (clavicular portion) in frontal-lateral
cross, dumbbells exercises. Electromyography and Clinical Neurophysiology. 43, 6774.
Ferreira, M.I., Büll, M.L., & Vitti, M. (2003b). Electromyographic validation of basic
exercises for physical conditioning programmes. The comparison of the response in
the deltoid muscle (anterior portion) and pectoralis major muscle (clavicular portion)
determined by the frontal-lateral cross, dumbbells and throwing exercises.
Electromyography and Clinical Neurophysiology. 43, 75-79.
Fridlund, A.J., and Cacioppo, J.T. (1986). Guidelines for human electromyographic
research. The Society for Psychophysiological Research, 23(5), 568-589.
Gerdle, B., Karlsson, S., Day, S., and Djupsjöbacka, M. (1999). Acquisition,
processing and
analysis of the surface electromyogram In U. Windhorst, H and H. Johansson (Ed.),
Modern Techniques in Neuroscience (pp.705-755). Berlin: Springer Verlag.
Glass, S., and Armstrong, T. (1997). Electromyographical activity of the pectoralis
muscle, during incline and decline bench presses. Journal of Strength and
Conditioning Research, 11, 163-167.
Goodman, C.A., Pearce, A.J., Nicholes, C.J., and Gatt, B.M. (2008). No difference in
1RM strength and muscle activation during the barbell chest press on a stable and
unstable surface. Journal of Strength and Conditioning Research, 22(1), 88-94.
Gouvali, M.K., and Boudolos, K. (2005). Dynamic and electromyographical analysis
in variants of push-up exercise. Journal of Strength and Conditioning Research,
19(1), 146-151.
Grange, R.W., Vandenboom, R., and Houston, M.E. (1993). Physiological
significance of myosin phosphorylation in skeletal muscle. Canadian Journal of
Applied Physiology, 18, 229-242.
Green, C.M., and Comfort, P. (2007). The affect of grip width on bench press
performance and risk of injury. Journal of Strength and Conditioning Research, 29
(5), 10.
Hakkinen, K., Alen, M., and Komi, P.V. (1985). Changes in isometric force and
relaxation time, electromyographic and muscle fibre characteristics of human
skeletal muscle during strength training and detraining. Acta Physiologica
Scandinavica, 125, 573-585.
Hakkinen, K., Kauhanen, H., and Kuoppa, T. (1987). Neural, muscular and hormonal
adaptations, changes in muscle strength and weightlifting results with respect to
variations in training during one year follow-up period of finish elite weightlifters.
World Weightlifting (IWF), 87(3), 2-10.
Hakkinen, K., Kauhanen, H., Pakarinen, A.J., and Komi, P.V. (1988). Neuromuscular
adaptations and serum hormones during one year training of elite junior weightlifters.
International Journal of Biomechanics, XI-B, 889-894.
Hakkinen, K., Komi, P.V., Alen, M., and Kauhanen, H. (1987). EMG, muscle fibre
and force production characteristics during a 1 year training period in elite weightlifters. European Journal of Applied Physiology, 56, 419-427.
Hakkinen, K., and Paavo, K.V. (1999). Effects of fatigue and recovery on
electromyographic and isometric force- and relaxation-time characteristics of human
skeletal muscle. European Journal of Applied Physiology and Occupational
Physiology, 55(6), 588-596.
Hamanda, T., Sale, D.G., MacDougall, J.D., and Tarnopolski, M.A. (2000).
Postactivation potentiation, fibre type, and twitch contraction time in human knee
extensor muscles. Journal of Applied Physiology, 88, 2131-2137.
Hermens, H.J., Frericks, B., Disslehorst-Klug, C., and Rau, G. (2000). Development
of recommendations for SEMG sensors and sensor placement procedures. Journal
of Electromyography and Kinesiology, 10, 361-374.
Hoyt, C. (1941). Test reliability estimated by analysis of variance. Psychometrika, 6,
153–160.
Hyson, S. (2010). Bench Press vs Shoulder Press. Journal of Strength and
Conditioning Research, 26(8), 20-22.
Iglesias-Soler, E., Paredes, X., Carballeira, E., Marquez, G., and Fernandez-DelOlmo, M. (2011). Effect of intensity and duration of conditioning protocol on postactivation potentiation and changes in H-reflex. European Journal of Sport Science,
11(1), 33-36.
Konrad, P. (2005) (1st ed.). The ABC of EMG: A practical introduction to kinesiology
electromyography. USA: Noraxon Inc.
Lander, J., Bates, B., Sawhill, J., and Hamill, J. (1985). A comparison between free
weight and isokinetic bench pressing. Journal of Sports Medicine in Sport and
Exercise Science, 17, 344-353.
Larsson, B., Karlsson, S., Eriksson, M., and Gerdle, B. (2003). Test-retest reliability
of EMG and peak torque during repetitive maximum concentric knee extensions.
Journal of Electromyography and Kinesiology, 13(3), 281-287.
Lehman, G. (2005). The influence of grip width and forearm pronation/supination on
upper-body myoelectric activity during the flat bench press. Journal of Strength and
Conditioning Research, 19(3), 587-591.
Lehman, G.J., MacMillan, B., MacIntyre, I., Chivers, M., and Fluter, M. (2006).
Shoulder muscle EMG activity during push up variations on and off a Swiss ball.
Dynamic Medicine, 9, 5-7.
Lehman, G.J., and McGill, S.M. (1999). The importance of normalization in the
interpretation of surface electromyography: A proof principle. Journal of Manipulative
and Physiology Therapeutics, 22(7), 444-447.
Lindstrom, L.H., and Magnusson, R.I. (1977). Interpretation of myoelectric power
spectra: a model and its applications. Proceedings of the IEEE, 65, 653-662.
Locono, C.U. (2004). Test-retest reliability of static EMG scan configural profiling.
Journal of Applied Physiology and Biofeedback, 29(1), 35-50.
Lowery, M.M., Stoykov, N.S., and Kuiken, T.A. (2003). A stimulation study to
examine the use of cross-correlation as an estimate of surface EMG cross talk.
Journal of Applied Physiology, 94, 1324-1334.
Maestu, J., Cichella, A., Purge, P., Ruosi, S., Jurimae, J., and Jurimae, T. (2006).
Electromyographic and neuromuscular fatigue thresholds as concepts of fatigue.
Journal of Strength and Conditioning Research, 20(4), 824-828.
Manning, R.J., Graves, J.E., Carpenter, D.M., Leggett, S.H., and Pollock, M.L.
(1990). Constant vs variable resistance knee extension training. Medicine and
Science in Sports and Exercise, 22, 397-401.
Masiulis, N., Skurvydas, A., Kamandulis, S., Snieckus, A., Brazaitis, M.,
Daniuseviciute, L., and Ramanauskiene, I. (2008). Post-activation potentiation and
fatigue in quadriceps femoral muscle after a 5s maximal voluntary isometric
contraction. Education Physical Training and Sport, 68, 55-56.
Mathiassen, S., Winkel, J., and Hagg, G. (1995). Normalization of surface EMG
amplitude from the upper trapezius muscle in ergonomic studies—a review. Journal
of Electromyography and Kinesiology, 5, 197-226.
Mathiassen, S.E. (1997). A checklist for normalisation of surface EMG amplitude In
H. Hermens, G. Hagg and B. Freriks (Ed.), Proceedings of the Second General
SENIAM Workshop (pp. 21-47) Sweden: Stockholm.
Mathur, S., Eng, J.J., and MacIntyre, D.L. (2005). Reliability of surface EMG during
sustained contractions of the quadriceps. Journal of Electromyography and
Kinesiology, 15, 102-110.
McArdle, W.D., Katch, F.I., Katch, V.L. (2010) (7th ed.). Exercise physiology:
nutrition, energy, and human performance. USA: Lippincott Williams and Wilkins.
McCaw, S., and Friday, J. (1994). A comparison of muscle activity between a free
weight and machine bench press. Journal of Strength and Conditioning Research, 8,
259-264.
McGill, S., Juker, D., and Kropf, P. (1996). Appropiately placed surface EMG
electrodes reflect deep muscle activity (psoas, quadrates lumborum, abdominal wall)
in the lumbar spine. Journal of Biomechanics, 29(11), 1503-1507.
McLaughlin, T.M. (1984). Grip spacing and arm position. Powerlifting USA, 8(6), 24.
McLaughlin, T.M., and Madsen, N.H. (1984). Bench Press techniques of elite
heavyweight powerlifters. Journal of National Strength and Conditioning Association,
6, 44-65.
Merletti, R., Gulisashvili, A., and Lo Conte, L.R. (1995). Estimation of shape
characteristics ofsurface muscle signal spectra from time domain data. IEEE
Transactions on Biomedical Engineering, 42(8), 769–776.
Metzger, J.M., Greaser, M.L., & Moss, R.L. (1989). Variations in cross-bridge
attachment rate and tension with phosphorylation of myosin in mammalian skinned
skeletal muscle fibers. Implications for twitch potentiation in intact muscle. The
Journal of General Physiology, 93, 855-883.
Mezzarane, R.A., and Kohn, A.F. (2009). A method to estimate EMG crosstalk
between two muscles based on the silent period following an H-reflex. Journal of
Medical Engineering and Physics, 31(10), 1331-1336.
O’Leary, D.D., Hope, K., and Sale, D.G. (1997). Post-tetanic potentiation of human
dorsiflexors. Journal of Applied Physiology, 83, 2131– 2138.
Oliveira, L.F., Matta, T.T., Alves, D.S., Garcia, M.A.C., and Viera, T.M.M. (2009).
Effect of shoulder position on the biceps brachii EMG in different dumbbell curls.
Journal of Sports Science and Medicine, 8(1), 24-26.
Pearson, S.N., Cronin, J.B., Hume, P.A., and Slyfield, D. (2009). Kinematics and
kinetics of the bench press and bench pull exercises in a strength trained sporting
population. International Journal of Sports Biomechanics, 8(3), 245-254.
Pedhazur, E.J., & Pedhazur-Schmelkin, L. (1991). Measurement, design, and
analysis: An integrated approach. Hillsdale, NJ: Erlbau.
Requena, B., Zabala, M., Ribas, J., Ereline, J., Paasuke, M., and Gonzalez-Badillo,
J.J. (2005). Effect of post-tetanic potentiation of pectoralis and triceps brachii
muscles on bench press performance. Journal of Strength and Conditioning
Research, 19(3), 622-626.
Richards, J.A., and Dawson, T.A. (2009). Optimizing exercise outcomes: the efficacy
of resistance training using conventional Vs. novel movement arcs. Journal of
Strength and Conditioning, 23(7), 2015-2024.
Richmond, S.R., and Godard, M.P. (2004). The effects of varied rest periods
between sets of failure using the bench press in recreationally trained men. Journal
of Strength and Conditioning Research, 18(4), 846-849.
Sadri, I., Jourkesh, M., Ostojic, S.M., Calleja- Gonzalez, J., Ojagi, A., and Neshati, A.
(2011). A comparison of EMG fluctuation of deltoid and pectoralis major muscles in
bench press. Department of Physical Education and Sports Science, 4(1), 30-33.
Sandercock, T.G. (1985). Single motor unit and fibre action potentials during fatigue.
Journal of Applied Physiology, 58(4), 1073-1079.
Sandler, D. (2010). Dumbbell flye/press. Joe Weider’s Muscle and Fitness, 71(4),
204.
Schik, E.E., Coburn, J.W., Brown, L.E., Judelson, D.A., Khamoui, A.V., Tran, T.T.,
and Uribe, B.P. (2010). A comparison of muscle activation between a smith machine
and a free weight bench press. Journal of Strength and Conditioning Research,
24(3), 779.
Scoville, C.R., Arciero, R.A., Taylor, D.C., Stoneman, P.D. (1997). End range
eccentric antagonist/concentric agonist strength ratios: a new perspective in
shoulder strength assessment. Journal of Orthopaedic Sports and Physical Therapy,
25(3), 203-207.
Solomonow, M., Baratta, R., Bernardi, M., Zhou, B., Lu, Y., Zhu, M., and Acierno, S.
(1994).
Surface
and
wire
EMG
in
neighbouring
muscles.
Journal
of
Electromyography and kinesiology, 4(3), 131-142.
Tan, B. (1999). Manipulating resistance training program variables to optimize
maximum strength in men: A Review Journal of Strength and Conditioning
Research, 13(3), 289-304.
Tryon, R.C. (1957). Reliability and behavior domain validity: Reformulation and
historical critique. Psychological Bulletin, 54, 229–249.
Van, W.W. (1993). Effects of external load and abduction angle on EMG level of
shoulder muscles during isometric contractions. EMG Clinical Neurophysiology, 33,
185–191.
Van den Tillar, R., and Ettema, G. (2010). The “Sticking period” in a maximum bench
press. Journal of Sports Sciences, 28(5), 529-535.
Vieira, T.M., Merletti, R., and Mesin, L. (2010). Automatic segmentation of surface
EMG images: Improving the estimation of neuromuscular activity. Journal of
Biomechanics, 43(11), 2149-2158.
Wagner, L.L., Evans, S.A., Weir, J.P., Housh, T.J., and Johnson, G.O. (1992). The
effect of grip width on bench press performance. International Journal of Sports
Biomechanics, 8, 1-10.
Wahl, M.J., and Behm, D.G. (2008). Not All instability training devices enhance
muscle activation in highly resistance-trained individuals. Journal of Strength and
Conditioning Research, 22(4), 1360-1370.
Wilson, G.J., Elliott, B.C., and Kerr, G.K. (1989). Bar path and force profile
characteristics for maximal and submaximal loads in the bench press. International
Journal of Sport Biomechanics, 5(4), 390-402.
APPENDICIES
PARTICIPATION INFORMATION SHEET
Title of Project: A Comparison of muscle activation between a conventional bench
press and using the bench press block.
PARTICIPANT INFORMATION SHEET
THANK YOU FOR AGREEING TO TAKE PART IN THE STUDY
The bench press exercise is a very popular exercise choice with resistance training
individuals and it is what most people use to measure their strength by. All resistance
training individuals are always seeking to find new ways of improving the bench press
exercise. There are many different well known methods that are used to improve the bench
press. Recently, an increasing more popular method that is being used to develop the bench
press exercise is to incorporate the use of bench press blocks. A bench press block is
designed to reduce the range of motion to develop strength at the sticking point of the lift.
This occurs due to the delay of switching from one set of activated muscles to another.
Therefore, muscle activation is very important. No research has yet to be done examining
the muscle activation levels with this training intervention. Understanding the differences in
muscle activation levels between the bench press with and without the use of bench press
blocks will gain knowledge of the dominant muscles at each phase of the bench press lift.
This knowledge can then be used to develop the bench press further.
WHY YOU?
You are being asked because you are familiar with the bench press exercise and are
interested in resistance training. We think you will benefit from this study as a result.
WHAT WILL HAPPEN?
The study will take part over a two day period with 24hours recovery inbetween each day.
The two days will consist of:
1. Day one, your will have time to familiarise with the bench press exercise and the use
of the bench press block. You will also be required to test your 1RM (one rep max)
on both interventions so that loads can be calculated effectively on the test day.
2. Day two, you will be required to perform a full conventional bench press at ≥90% of
their 1RM. You will have to be prepared to have all dead skin and hair removed from
pre-arranged sites to reduce skin resistance. Surface electrodes will then be placed
over the belly of muscles so that motor unit activity can be quantified. After sufficient
rest, the same procedures will apply but you will be required to perform the second
intervention, the bench press with the use of the bench press block.
ARE THERE ANY BENEFITS OF TAKING PART IN THE STUDY?
Yes, as you’re interested in resistance training, this is a great opportunity for you to establish
your 1RM (one repetition max) bench press, increase your knowledge of the bench press
exercise and find new ways of developing the bench press.
ARE THERE ANY RISKS?
Obviously there are risks associated with resistance training. However, this is why you have
been chosen to take part in the study because you are already familiar with the bench press
exercise. Warming up and stretching will be required before taking part in the study to
prevent injury. If you are feeling unwell, any twitches or pains on the test days, we’d advise
that you do not take part. You will not be forced into doing anything you do not want to.
However, it would be grateful if you inform us of your absence.
DO I HAVE TO?
No, you don’t. Participation is entirely voluntary and you are able to drop out at any stage in
the study without reasoning and without a disadvantage - just tell us.
WHAT HAPPENS NEXT?
With this information sheet you will find a consent form. If you are willing to take part in the
study, please complete the consent form and return it to myself as soon as possible. My
details are given on this document.
YOUR RIGHTS?
You have full legal rights when agreeing to take part in the study. If something was to go
wrong at any part during the study, UWIC fully secures its staff, and participants are covered
by its insurance.
WHAT WE DO?
The results from the three days will be stored securely at UWIC. All results from the study
will be presented into a report to UWIC. However, all details will be coded so that you will not
be able to be identified from the information being displayed.
HOW WE PROTECT YOUR PRIVACY:
Your privacy is taken into consideration and respected by all members involved in the study.
We are ensuring that you cannot be made identifiable from any of the information we display
in the study.
All the information about you will be stored securely in a cabinet at UWIC. After the study
has been conducted, we will destroy the information we have gathered about you apart from
the consent forms. These will be kept for the following ten years as this is what is required of
us by UWIC.
HAVE YOU GOT ANY QUESTIONS?
If you have any questions just contact me.
Ryan Stevens

[email protected]
07527226692
QUESTIONNAIRE
Questionnaire
Thank you for taking your time in filling out this questionnaire, your personal information will
remain private and confidential. I am looking for 10-15 individuals to participate in a research
study, comparing the muscle activation levels between a conventional bench press and
using a bench press block.
The following questionnaire will allow us to determine whether you are a suitable candidate
to participate in the study.
Name:
Age:
Email address:
1. How often do you actively engage in resistance training?
Once a week □
Twice a week □
Three times a week □
Four times a week □
Five times a week or more □
2. Is the bench press exercise part of your current training regime?
Yes □
No □
3. Have you ever performed the bench press exercise before?
Yes □
No □
If `No’ there is no need to complete the remainder of the questionnaire, thank you for
your time.
4. When the bench press exercise is part of your training regime, how often do
you bench press a week?
Once a week □
Twice a week □
Three times or more □
5. On average, how much experience would you consider yourself to have of the
bench press exercise?
Less than one year □
One year □
Two years □
Three years □
Four years or more □
If you selected `less than one year’ there is no need to complete the remainder of the
questionnaire, thank you for your time.
6. Have you ever you used a bench press block as a method to develop your
bench press?
Yes □
No □
7. Have you ever suffered any injuries as a result of resistance training?
Yes □
No □
If `Yes’ please provide details below.
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
_____________________________________________
8. Have you ever suffered any injuries as a result of the bench press exercise?
Yes □
No □
If `Yes’ please provide details below.
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
_____________________________________________
9. Do you currently suffer from any injuries, twitches, pains and/or any medical
condition that may prevent, make it difficult and/ or cause you pain when
performing the bench press exercise?
Yes □
No □
If `Yes’ please provide details below.
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
_____________________________________________
Thank you for your time in completing the questionnaire.
PARTICIPANT CONSENT FORM
PARTICIPANT CONSENT FORM
Title of Project: A Comparison of muscle activation between a conventional
bench press and using the bench press block
Name of Researcher: Ryan Stevens
The information sheet for the study has been read and understood. I understand all the tests
and procedures involved and what is expected of me. Any questions that I have had have
been answered. I understand that I am able to seek further information.
I know that:

My participation is voluntary. I am required to complete all the tests. However, I
am also able to leave the study at any point in time without giving a reason and
will not be punished.

The study will require my attendance to three separate sessions.

As part of the study, I will have data recorded and will be required to have dead
skin and hair removed from prearranged sites.

The results from the tests are for the purpose of the study only. All information
will be stored securely in a cabinet at UWIC. The results will be put into a report
and maybe published but my personal identity will not be displayed.
__________________________
_______________
Your Name
Date
________________________________________________
Your Signature