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Journal of Bodywork & Movement Therapies (2012) 16, 488e492
Available online at www.sciencedirect.com
journal homepage: www.elsevier.com/jbmt
MUSCLE PHYSIOLOGY
The effect of fatigue and velocity on the relative
timing of hamstring activation in relation to
quadriceps
Maryam Abbaszadeh-Amirdehi, MSc, PT a,
Khosro Khademi-Kalantari, PhD, PT b,*, Saeed Talebian, PhD, PT a,
Asghar Rezasoltani, PhD, PT c, Mohammad Reza Hadian, PhD, PT d
a
Department of Physiotherapy, Faculty of Rehabilitation, Tehran University of Medical Sciences, Tehran, Iran
Department of Physiotherapy, Physiotherapy Research Center, Faculty of Rehabilitation, Shahid Beheshti University of
Medical Sciences, Damavand Ave. Opposite to Bo-Ali Hospital, 1616931111 Tehran, Iran
c
Department of Physiotherapy, Shahid Beheshti University of Medical Sciences, Faculty of Rehabilitation, Tehran, Iran
d
Department of Physiotherapy, Faculty of Rehabilitation, Brain and Spinal Injury Research Center, Tehran University of
Medical Sciences, Tehran, Iran
b
Received 30 April 2012; received in revised form 16 June 2012; accepted 1 July 2012
KEYWORDS
Fatigue;
Velocity;
Timing;
Hamstring;
Quadriceps;
Activation
Summary Inter-muscular coordination has an important role in proper function and prevention of injuries in the knee joint. The purpose of this study was to characterize the effect of
velocity and fatigue on the relative activation onset of hamstring to quadriceps muscles during
knee extension. Thirty one healthy and non-athletic volunteers (24 women, 7 men) were recruited for the study. The onset time of vastus medialis, vastus lateralis, rectus femoris,
medial and lateral hamstring were measured during maximum voluntary extension of the knee
joint at velocities of 45 /s, 150 /s & 300 /s before and after fatigue and the mean delay onset
of all pairs of H-Q were measured. A two-way repeated measures ANOVA test was used to
compare across the mean delayed onset of hamstring related to quadriceps muscles at various
velocities. Hamstring muscle showed a delayed activation related to quadriceps and increasing
the velocity of shortening has a prominent effect on the inter-muscular coordination with early
activation of hamstring related to quadriceps muscles (F Z 6.7, p < 0.002 for Biceps-rectus
femoris, F Z 6.31, p < 0.003 for semitendinosus-rectus femoris, F Z 6.26, p < 0.003 for
biceps-vastus lateralis, F Z 5.98, p < 0.004 for semitendinosus-vastus lateralis, F Z 3.19,
p < 0.04 for biceps-vastus medialis and F Z 3.2, p < 0.04 for semitendinosus-vastus medialis).
* Corresponding author. Tel.: þ98 21 77561411; fax: þ98 21 77561406.
E-mail address: k_khademi@sbmu.ac.ir (K. Khademi-Kalantari).
1360-8592/$ - see front matter ª 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.jbmt.2012.07.002
Fatigue and velocity effect on muscle activation timing
489
This could predispose these muscles to over strain and possible injuries. The main effect of
fatigue condition and its interaction with velocity however, showed statistically nonsignificant
result.
ª 2012 Elsevier Ltd. All rights reserved.
Introduction
Methods
Inter-muscular coordination has a major role in function
and prevention of injuries in the knee joint (Billaut et al.,
2005). It has been recently shown that the three most
common sites of injury for senior or junior runners are the
knee, foot and leg. Knee injuries should be a public health
concern because it increases the likelihood of discontinuing
regular physical activity and developing osteoarthritis
(Lohmander et al., 2004).
Among knee injuries, ACL injuries and hamstring muscle
injuries are the most common ones. Hamstring injuries are
the most prevalent muscle injury in sports involving rapid
acceleration and maximum speed running. There have been
several factors hypothesized to contribute to the risk of
hamstring injury including inadequate warm-up, fatigue,
previous injury, knee muscle weakness or strength imbalance, increasing age, poor movement discrimination, poor
flexibility, increased lumbar lordosis and poor running
technique (Hoskins and Pollard, 2005; Foreman et al.,
2006).
Hamstring injury is mainly attributed to eccentric
mechanisms which are occurred during the late swing and
early stance phase of running. During these periods the
hamstring muscles act as a decelerator to control hip and
knee motion in the late swing phase or to provide hip
extensor torque in the early stance phase. During sprinting,
these events occur over a very short period of time, and if
the inter-muscular coordination is poor, muscle strain
injury may occur.
Inter-muscular coordination may also have a significant
role in controlling the amount of loading of the knee ligaments especially anterior cruciate ligament. Quadriceps
muscles produce extensor torque in the knee as well as
vigorous anterior shear force to tibia. The most resultant
anterior shear force applied to the tibia due to contraction
of quadriceps muscles is occurred in terminal extension of
the knee joint. This shear force is tolerated by anterior
cruciate ligament. Hamstring muscles, with posterior
attachment to tibia on the other hand, produce posterior
shear force that would neutralize the amount of stress on
the anterior cruciate ligament (Shelburne and Pandy, 1997;
Lutz et al., 1993; Orchard and Seward, 2002). Numerous
studies have evaluated the ratio of hamstring and quadriceps muscles activation during different activities (Croce
and Miller, 2003; Reilly and Marfell-Jones, 2003; Jnhagen,
2005; Olyaei et al., 2006). Little is known about the
temporal pattern of activation of quadriceps and hamstring
muscles and the factors that may affect it. Coordinate
activation of these antagonist group of muscles are crucial
for the knee joint stability and also any impairment in this
temporal coordination can predispose the ACL and also
hamstring muscles to injury.
Participants
Thirty-one healthy and non athletic participants (24 female
& 7 male, age: 23.5 2.5 years, height: 165 10 cm,
weight: 60 9) were recruited for this study. Each participant provided informed written consent, and the experimental protocol was approved by local Research Ethics
committee.
Procedure
An isokinetic dynamometer (Biodex Medical System, Inc.
Shirley, New York) was used to apply different knee flexionextension velocities and to measure the knee extensor
torque. Prior to the test, the cases with hamstring
contracture were identified and excluded from the study.
The participant lies in supine position, flexes both hips to
90 and actively extend each knee as much as possible. For
normal flexibility in the hamstrings, knee extension should
be within 20 of full extension.
The leg with which the participant would kick a ball was
selected as dominant side for the experiment. In this study,
dominant leg of all participants was right leg. Surface EMG
of rectus femoris (RF), vastus medialis (VM), vastus lateralis
(VL), biceps femoris (BF) and semitendinosus (ST) were
recorded according to SENIAM guidelines (Hermens et al.,
1999). To minimize the movement artifacts, the electrodes were taped to the skin with surgical tape. The
ground electrodes were positioned on the wrist. The
participant seated with the hip fixed at 90 flexion with
strap. The axis of the dynamometer was aligned with the
axis of the knee, and the tibial pad was placed proximal to
the medial malleole. Various angular velocity sequences
including 45 /s, 150 /s and 300 /s were applied randomly
for each participant. Each participant performed three
repetition of maximum knee flexion-extension from 0 to 90
at each velocity with 10 s rest interval between different
velocities. The maximum torque and the onset time
were calculated for each muscle and at all velocities.
Sixty repetition of knee extension-flexion (concentriceconcentric) with max effort in angular velocities of
45 /s were done to fatigue the muscles which follows
immediately with 5 maximum knee extension-flexion at
150 /s and 300 /s. The last three trials at each velocity
were used for extracting the maximum torque and the
onset time after fatigue. The onset time of activation was
defined as the instant when the rectified SEMG passed
above the 3SD of the background EMG and lasted for more
than 10 ms. The mean delayed activation onset of
hamstring in relation to quadriceps muscles (H-Q onset
490
M. Abbaszadeh-Amirdehi et al.
delay) in the last 3 trials post fatigue was then calculated
by extracting the onset time of hamstring from quadriceps
muscles.
Measurements & data analysis
Data analysis was carried out using SPSS software, Version
16 and a priori significance level was set at 0.05. The
average values of dependent variables for three velocities
of each experimental condition were used for statistical
analysis. A 2 3 (fatigue and non-fatigue conditions, three
levels of velocities of movement) repeated measures
analysis of variance (ANOVA) test was used to determine
main effects and interactions of these factors for H-Q onset
delay. For multiple comparisons, the Bonferroni adjustment
method was used.
Intra class correlation of the last 3 trials pre and post
fatigue was also computed for the stability of the H-Q onset
delay.
Results
The ICC coefficient of the H-Q onset delay in the last 3 trials
pre and post fatigue showed values ranged from 0.82
to 0.93.
Hamstring muscle activated with a delay related to
quadriceps muscles during knee extension at all velocities.
The changes in the H-Q onset delay at different velocities,
before and after fatigue can be seen in Table 1. The main
effect of velocity was statistically significant for all pairs of
H-Q onset delay; meaning that with increasing the velocities the delay onset of hamstring muscles to quadriceps was
decreased (Fig. 1). The main effect of fatigue and the
interaction of fatigue and velocity on the other hand, were
statistically nonsignificant. The F ratios and p values for all
pairs of H-Q onset delay can be seen in Table 2.
Multiple comparisons showed that the delayed activation onset of BF and ST in relation with VL showed significant decrease at velocity of 150 /s compared to 45 /s
before fatigue and between 45 /se150 /s and 45 /se300 /
s after fatigue (P < 0.01). Biceps femoris and ST also
showed earlier activation in relation to RF with increasing
velocity from 45 /s to 150 /s (p < 0.01) and also to 300 /s
(p < 0.001). When the onset time of ST and BF was
compared with VM, the changes in velocity showed statistically nonsignificant effect except for the velocity of 150 /
s compared to 45 /s (p < 0.03).
Discussion
The main findings of this study showed that significant
changes on the temporal coordination between hamstring
and quadriceps muscles can be interrupted at high velocity
and not by fatigue. Our results expressed that vastus lateralis and rectus femoris have an important role in the fast
knee movements and activation time differences between
these two muscles and hamstring muscles decreased with
increased velocity. Namely, with decision making for knee
extensors to contract at higher velocity, antagonist muscles
(hamstrings) were contracted earlier. This also means that
with increasing the rate of activation of Q muscles, utilization of semitendinosus and biceps femoris as a controller
at the beginning of motion also increases. It has been reported that with the increased velocity the amount of
stretch of hamstring does not change, however the amount
of negative work increases significantly (Thelen et al.,
2005). These can increase the risk of injuries at higher
velocity movements. Obviously, premature activation of
hamstring muscle at higher velocity can affect negative
work calculated in this research which is similar to the
results of Thelen et al. (2006).
The acceptable correlation coefficient of the H-Q onset
delay in the 3 trials used for extracting the data, pre and
post fatigue, suggests the temporal stability of neuromuscular control on the knee musculature. This would also
implies that averaging the delay time in the last 3 trials pre
and post fatigue could represent a reliable values for each
participant and at all conditions.
There isn’t statistically significant difference of delayed
activation onset of hamstring related to VM across the
studied velocities. This may indicate that vastus medialis
are not involved in the fast movements and motor
programming of this muscle does not change along with
changes in velocities. Co-contraction of this muscle with its
antagonist muscle is defined with fixed schedule timing.
Our results mainly showed insignificant changes in H-Q
onset delay with increasing the velocity from 150 /s to
300 /s. This can be due to the low optimum maximum
torque of knee musculature activation and the constant
rate of motor programming in the CNS in our non athletic
participants. It is plausible that elite athletes involving in
high speed sports such as sprinters may show continuously
earlier activation of hamstrings with increasing the velocity
to higher values.
The fatigued muscles showed statistically insignificant
changes in the H-Q onset delay. It seems that corrupted
Table 1 Mean SD of activation time of H-Q muscles at different velocities and conditions. The * represent the significant
values compared to velocity of 45 at each condition.
Non fatigue
Fatigue
Velocity (%s)
ST-VM (msec)
45
150
300
45
150
300
68
48
50
76
50
53
77
40*
28
46
34*
99
BF-VM (msec)
53
38
45
60
33
48
81
35*
28
46
33*
58
ST-VL (msec)
87
58
64
77
62
52
66
29*
42
42
34*
90*
BF-VL (msec)
74
48
58
61
46
52
49
29*
38
34
32*
90*
ST-RF (msec)
89
60
55
76
65
48
65
41*
41*
51
40
99
BF-RF (msec)
75
50
50
60
49
43
47
36*
30*
41
38
52
Fatigue and velocity effect on muscle activation timing
491
Figure 1 The mean changes of delay onset time of H-Q muscles activation at three different velocities and two conditions. The
lower values represent the shorter delay of hamstring muscle activation in relation to quadriceps muscles.
temporal inter-muscular coordination is not the possible
mechanism that fatigue can predispose the knee joint
ligaments or hamstring muscles to injury. It is known that
fatigue can be caused by many different mechanisms
commonly classified as central and peripheral. Knowing
Table 2
that the mechanisms that cause fatigue are specific to the
task being performed, it is possible that different method
to induce fatigue may result in different outcomes.
The results of this study are similar to the results of
studies done on woman athletes (Rozzi et al., 1999), but
F ratios and P values of all pairs of H-Q onset delay.
ST-VM
Condition (fatigue, non fatigue)
Velocity
Condition * Velocity
BF-VM
ST-VL
BF-VL
ST-RF
BF-RF
F
Sig.
F
Sig.
F
Sig.
F
Sig.
F
Sig.
F
Sig.
0.22
3.10
0.05
0.64
0.05
0.94
0.03
3.19
0.32
0.86
0.04
0.72
0.41
5.98
0.48
0.52
0.004
0.61
0.09
6.26
0.94
0.15
0.03
0.39
0.19
6.31
0.61
0.66
0.003
0.54
1.22
6.71
0.8
0.27
0.002
0.45
492
are opposed to the study of Billaut et al. (2005). Totally, the
results of this study represent the more specific effect of
high velocity and not fatigue on the activation onset of
hamstring to quadriceps muscles. It seems that movement
controller system (eccentric contraction of hamstring) act
quicker in higher velocity to control and coordinate activities appropriately.
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