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Muscle Function & Biomechanics
SR3S02
Laboratory Report: Hamstring Quadriceps Ratio
Word Count: 1424
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Sufficient strength of the quadriceps and hamstrings is essential for lower limb
biomechanics alongside sports performance, particularly in activities requiring
jumping, landing and running. These muscle groups are functional antagonists
(Willigenburg et al, 2014), meaning the contraction of the quadriceps muscle results
in knee extension whilst hamstring contraction initiates knee flexion. Insufficient
strength or imbalance of the thigh musculature may contribute to reductions in sports
performance and may also make an athlete susceptible to muscle strain or kneerelated injury (Freckleton and Pizzari, 2013; Myer et al, 2009). Testing for lower-limb
strength imbalances often looks at the hamstring quadriceps ratio (H/Q ratio) which
tests peak torque (PT) in both muscle groups using an isokinetic machine. H/Q ratio
testing has been used to evaluate an individual’s capacity to perform during sports
while also being a preventative strategy in screening for potential injury (Myer et al,
2009; Yeung et al, 2009).
Isokinetic muscle strength tests are commonly used to assess quadriceps and
hamstring muscle strength in athletic and non-athletic individuals (Lanshammar and
Ribom, 2011). Isokinetic testing can be performed to test concentric or eccentric
muscle strength at fixed angular velocities, with the measure of force developed
through the quadriceps and hamstring muscles. At low velocity (0-180/s°-1), peak force
reflects muscular strength, where higher velocity (>180/s°-1) values are influenced by
neuromuscular control (Willigenburg et al, 2014). Higher velocity testing is shown to
better represent muscle function during athletic activity over lower velocities (Iossifidou
et al, 2005). Leading from this point, there are different variations of the H/Q ratio, with
the conventional ratios comparing concentric strength of the hamstrings and
quadriceps (Aagaard et al, 1998). However, athletic activities require movements that
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will need the hamstrings to function eccentrically to resist and control the contraction
of the quadriceps which takes place during running and kicking actions (Yeung et al,
2009), this has been referred to as the functional ratio.
Table 1. Calculations for conventional and function hamstring: quadriceps ratios.
Type of Ratio
Calculation
Reference
Conventional H/Q Ratio
(maximal leg flexor concentric peak torque/ maximal
(Aagaard et al, 1998)
leg extensor concentric peak torque)
Functional H/Q Ratio
(maximal leg flexor eccentric peak torque /maximal
(Costa et al, 2013)
leg extensor concentric peak torque )
It was first suggested that knee extensor muscle strength should be higher than knee
flexors strength in a magnitude of 3:2 (66%) (Steindler, 1955). Isokinetic reports
analysed concentric muscle actions with recommendations for optimal H/Q ratios in a
range of 50 to 80% (Kannus, 1994), with more recent reports of H/Q ratios lower than
60% at a velocity of 180/s°-1 to be at a higher risk of hamstring injury (Yeung et al,
2009). Isokinetic performance is influenced by a number of variables including age,
gender, adaptions to the level and type of sport or training, muscle fatigue and static
stretching (Cheung et al, 2012; Andrade et al, 2012; Fousekis et al, 2010; Pinto et al,
2018; Costa et al, 2013). Therefore, normative values will need to be considered when
applying under different conditions or populations. The objective of this study was to
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compare H/Q ratios between both legs and at different velocities whilst understanding
the use of H/Q ratios.
Methodology
Subjects
Eight individuals (7 male and 1 female; age + SD = 21.3 + 0.8 years; height = 174.6 +
5.7 cm; body mass = 83.5 + 12.2 kg) who come from a variety sports backgrounds,
volunteered to take part in a university class study. Before any testing participants
were informed in the study procedure before giving consent to participate. Strength
and anthropometry data was analysed for this study.
Procedure/Statistical Analysis
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Strength measurements were obtained using an isokinetic dynamometer (Humac
Norm 770; Computer Sports Medicine Inc, Stoughton, MA). Participants were given a
standardised warm-up before testing, which included a 5-minute moderate-intensity
bout of treadmill jogging. Anthropometric data including age, gender, body mass and
height was collected alongside identifying the individual’s dominant leg. Participant
positioning on the isokinetic dynamometer was routinely set-up according to the
Humac Norm guidelines, the ‘long form torque vs time’ protocol was selected. After
participants were familiarised with the setup (5 submaximal warm-up repetitions,
followed by 30 second rest) two isokinetic tests were carried out, first the angular
velocity (ω) was set at 60/s°-1 for 5 maximal repetitions of knee flexion and extension
followed by a minutes rest before another warm-up preceding a 15 maximal repetition
test at ω 180/s°-1. Participants were advised to grip the handles whilst performing the
repetitions accompanied by strong verbal encouragement. A maximum of 5 minutes
rest was given before alternating legs to repeat testing. Proceeding confirmation of
normal distribution (Shapiro-Wilk), t-tests were used to determine if there were bilateral
and velocity differences in variables.
Table 2. Summary of isokinetic strength test.
Angular Velocity (ω)
Familiarisation Repetitions
Test Repetitions
Concentric Quadriceps/Hamstring
5
5
5
15
60/s°-1
Concentric Quadriceps/Hamstring
180/s°-1
Results
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Table 3. Hamstring/ Quadriceps ratio from peak torque values, average power per repetition and joint
angles at peak torque of both dominant and non-dominant legs at different isokinetic angular velocities.
Mean + SD. * = Significant difference between knee angular velocities (P <0.05). ** = Significant difference between knee
angular velocities (P<0.01). † =Significant difference between dominant and non-dominant legs (P<0.05).
Dominant leg
Non-dominant leg
60/s°-1
180/s°-1
60/s°-1
180/s°-1
57 + 13.3
62.6 + 7.9
53.8 + 5.7
63.1 + 12.9
Hamstring
98.4 + 18.2**†
158.1 + 40**†
92 + 17.5**†
145.5 + 36.2**†
Quadriceps
154 + 29.6**
243.6 + 57.3**
158 + 33.5*
228.9 + 73.1*
Hamstring
29.8 + 9.5
34 + 3.3
27.6 + 8.7*
35.1 + 6.2*
Quadriceps
62.9 + 15.8*†
55.8 + 17.2*
54 + 11.7*†
49.3 + 10.5*
Hamstring Quadriceps
Ratio (%)
Average Power (watts)
Joint Angle at peak torque (°)
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Dominant leg
300
**
160
Hamstring Peak Torque (N⋅m)
Quadriceps Peak Torque (N⋅m)
**
180
Non-dominant leg
250
200
150
100
50
Dominant leg
**
Non-dominant leg
**
140
†
120
100
80
60
40
20
0
0
60.s°
180.s°
Knee Angular Velocity (s°)
Figure 1 - Peak torque in quadriceps at two knee angular
velocities. ** = Significant difference between knee angular
velocities (P<0.01). † =Significant difference between dominant
and non-dominant legs (P<0.05). Data is presented as mean
(SD).
60.s°
180.s°
Knee Angular Velocity (s°)
Figure 2 - Peak torque in hamstrings at two knee angular
velocities. ** = Significant difference between knee angular
velocities (P<0.01). † =Significant difference between dominant
and non-dominant legs (P<0.05).Data is presented as mean
(SD).
As shown in (table 3), the hamstring/
quadriceps ratio does not have any significant differences between knee angular
velocities (60°-1 and 180°-1) or between legs. Average power of the hamstrings (table
3) are significantly higher at 180°-1 in both legs when compared to 60°-1, with the
dominant leg being significantly greater at both angular velocities. The average power
of the quadriceps (table 3) are greater (P <0.01) in the 180°-1 velocity compared to 60°1
with mean differences in the dominant leg of (89.6 watts) and in the non-dominant
leg (70.9 watts). Joint angle at peak torque (table 3) of the hamstrings is greater
(P<0.05) in the non-dominant leg at 180°-1 than at 60°-1 by 7.5°. Joint angle in the
quadriceps is greater (P<0.05) during 60°-1 angular velocity in both legs with the
dominant leg being significantly higher (P<0.05) by 8.9°. In figures 1 and 2, peak
torque values of the hamstrings and quadriceps are greatest in both legs at 60°-1
(P<0.01). Hamstring peak torque (figure 2) shows the dominant leg is significantly
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higher at angular velocity 180°-1 (89.9 + 18.5), comparative to the non-dominant leg at
180°-1 (83.3 + 17).
Discussion
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In comparing bilateral strength characteristics of the hamstrings and quadriceps
muscles in sports students, a main finding is that there were no differences in H/Q
ratio between legs, or at different velocities. H/Q ratios were not in the recognised area
of risk (below 60%) for potential hamstring or knee-related injury. Peak torque in both
muscle groups found increases between velocities. Other characteristics found
significant differences between legs including average power and joint angle at peak
torque. A general trend representing both legs is that differences were seen between
angular velocities, with the dominant leg eliciting greater changes with matched
workloads.
In regards to the main findings, conventional H/Q ratio did not change over angular
velocities, which is mostly inconsistent with other studies that find when velocity
increases, H/Q ratios also increase (Ruas et al, 2019). However, the current study
supports that of (Yoon et al, 1991) where angular velocity had no impact on H/Q ratios.
The current study found no bilateral H/Q ratio differences in contrast to (Ergun et al,
2004; Holcomb et al, 2007; Kong et al, 2010; Voutselas et al, 2007) with greater ratios
found in the dominant leg (Ergun et al, 2004; Kong et al, 2010; Voutselas et al, 2007).
Interestingly, training backgrounds and player positions have been shown to influence
dominant leg H/Q ratio in male professional soccer players (Voutselas et al, 2007;
Sliwowski et al, 2017) thus the need for consideration when comparing not only
population types but more specifically their physical requirements of their sporting role.
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Other examples of sports related adaptations include a study where female soccer
players found that the non-dominant leg had higher H/Q ratios (Holcomb et al, 2007).
Explanations behind this are again possibly due to the nature of the sport, as the nondominant leg is often used as a stabilising leg, thus during situations such as striking
a ball would involve the non-dominant leg to decrease the forward momentum of the
body, requiring the lower limb muscles to sustain the load-bearing (Griffin et al, 2000).
Velocities used in these studies were similar to the current study (60° s−1, 180° s−1,
240° s−1), so possible explanations to the differentiating results could be due to the
differences in participant characteristics, measurement devices and/or methods of
testing.
The current study does have some limitations, participant sample size was small and
were not assessed on training levels or sporting background prior to the study. Using
the conventional H/Q ratio calculated by peak torque does not consider other variables
that can influence the muscle relationship. Variables include torque produced at
various angles of range of motion, muscle activation, muscle size and fatigue. To
conclude, isokinetic testing can be used for sports performance, it may help coaches
and clinicians to monitor strength of the hamstring and quadriceps, whilst aiding
rehabilitation programmes possibly preventing risks of injury/imbalances. Further
investigation is needed on alternate methods of the H/Q ratio (angle-specific torque,
rate of torque development, muscle size, fatigue index and muscle activation), (Ruas
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et al, 2019) to determine their usefulness in the aim of performance enhancement and
injury reduction.
*Possibly add something about joint angles
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