Abstract
The impact of the hamstrings-to-quadriceps ratio on sport movement performance has not been sufficiently described. However, it seems that in movements involving eccentric-concentric muscular contractions, a higher hamstrings-to-quadriceps ratio should have a positive impact on human movement performance. The present study is aimed at identifying relationships between the hamstrings-to-quadriceps ratio and variables describing countermovement and drop jumps. The study was carried out in a group of 14 female soccer players. The tests were conducted using a Kistler force plate, an SG electrogoniometer, and the Biodex System 4 Pro dynamometer. Each player performed three countermovement jumps (CMJ) and three drop jumps (DJ) from heights of 15, 30, 45, and 60 cm. The peak torques of knee extensors and flexors were measured in isometric conditions and in isokinetic conditions at angular velocities of 30o/s, 60o/s, 90o/s, and 120o/s. Statistically significant relationships were found between the variables that describe CMJ, DJ 15, DJ 30, and hamstrings-to-quadriceps ratio at some, though not all, of the angular velocities measured. No significant relationships were found between the hamstrings-to-quadriceps ratio and variables that describe DJ 45 and DJ 60. The heights of CMJ, DJ 15, and DJ 30 were increased with higher hamstrings-to-quadriceps ratios. Analogous relationships were found between the hamstrings-to-quadriceps ratio and relative mechanical power during the take-off phase of the CMJ. Significant relationships between the hamstrings-to-quadriceps ratio and variables that describe vertical jump are likely to be observed if adequate angular velocity is used in the measurement of muscle torque.
Highlights
The commonly used conventional hamstrings-to-quadriceps (H/Q) ratio represents the ratio of concentric hamstring peak torque during lower limb flexion to concentric quadricep peak torque during lower limb extension [1]
Trzaskoma [10] found positive relationships between maximal power output developed during countermovement jumps (CMJ) and the value of the H/Q ratio calculated based on measurements of muscle torques performed under isometric conditions
In the group of female soccer players, the mean value of the H/Q ratio for the torques measured under isometric conditions was 42 ± 3 6%, whereas for the measurements performed under isokinetic conditions, the mean values were 48 8 ± 7 4%, 1 ± 7 4 %, 2 ± 7 2%, and 55 1 ± 8 3%
Summary
The commonly used conventional hamstrings-to-quadriceps (H/Q) ratio represents the ratio of concentric hamstring peak torque during lower limb flexion to concentric quadricep peak torque during lower limb extension [1]. The effect of the peak torque ratio of knee flexors and extensors on the risk of injury in the lower limbs has been extensively discussed in the literature [2,3,4,5,6]. It is generally accepted that a value of the flexor-extensor ratio above 0.6 (for measurements performed under isokinetic conditions) might be effective at preventing hamstring strain and anterior cruciate ligament (ACL) injury risk potential [2,3,4,5,6]. The question arises as to whether relatively high levels of muscle torque in knee flexors in comparison with extensors might positively affect sports movement performance. Trzaskoma [10] found positive relationships between maximal power output developed during countermovement jumps (CMJ) and the value of the H/Q ratio calculated based on measurements of muscle torques performed under isometric conditions
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