Isokinetic hamstring/quadriceps strength ratio: influence from joint angular velocity, gravity correction and contraction mode

Abstract

This study investigated isokinetic peak- and angle-specific hamstring/quadriceps strength ratios (conventional H/Q ratio) obtained during concentric and eccentric muscle contraction and examined the influence of joint angular velocity and the effect of gravity correction on these ratios. Also, a 'functional' H/Q ratio was defined by calculating eccentric hamstring strength relative to concentric quadriceps strength (Hecc/Qcon' representative for knee extension) and calculating concentric hamstring strength relative to eccentric quadriceps strength (Hcon/Qecc' representative for knee flexion). The H/Q ratio was calculated based on isokinetic peak moment and 50 degree-moment (0 degree = full extension) obtained at joint angular velocities 30, 120 and 240 degrees s-1. Gravity corrected conventional H/Q ratio remained constant across speeds and contraction mode, ranging from 0.47 to 0.54 and from 0.49 to 0.56 based on peak and 50 degree moment, respectively. In contrast, non-corrected H/Q ratio increased during concentric contraction from 0.58 at 30 degrees s-1 to 0.74 at 240 degree s-1 (P < 0.01). For knee extension at 240 degrees s-1 an Hecc/Qcon of 1.05 (peak) and 0.89 (50 degrees) was observed while for flexion at 240 degrees s-1 an Hcon/Qecc of 0.27 (peak) and 0.28 (50 degrees) was observed. In conclusion, gravity correction had high influence on the change in H/Q ratio with variation in extension velocity. A potential 1:1 hamstring/quadriceps strength relationship was demonstrated for fast knee extension, indicating a significant functional capacity of the hamstring muscles for providing muscular stability at the knee joint in such situations.

A comparison of isokinetic knee strength and power output ratios between female basketball and volleyball players

“…Previous investigations determined the eccentric peak torque for hamstrings to concentric quadriceps during fast knee extension. Aagaard et al [14,21] reported that functional H/Q increased above 100% with rising velocity and more extended knee joint positions. similarly, Gerodimos et al [27] demonstrated that this functional ratio increased with the growth of angular velocity.…”

“…Furthermore, schiltz et al [28] revealed the results of functional H/Q at 30 deg · s -1 /240 deg · s -1 velocities to be approximately 131% (dominant limb) and approximately 126% (non-dominant limb) in professional players. Thus, the functional H/Q > 100% during fast knee extension indicated the ability of eccentrically acting hamstrings to produce a braking joint flexor moment greater than the joint extensor moment exerted by the quadriceps [14,16,21].…”

“…This dynamic control ratio is considered more useful in determining injury risk than conventional H/Q [16,25]. Furthermore, the functional H/Q may better reflect the flexors and extensors coactivation pattern and the injury mechanism of the knee ligamentous structures [14,19].…”

“…Another proposed muscle strength ratio is functional H/Q, which is calculated by dividing the hamstrings peak torque during eccentric contraction by the quadriceps peak torque during concentric contraction at a specified angular velocity [14,16,17,24]. This dynamic control ratio is considered more useful in determining injury risk than conventional H/Q [16,25].…”

“…The hamstrings to quadriceps torque ratio (H/Q) is an important parameter for both training and rehabilitation [14][15][16][17][18][19][20]. In isokinetic tests, the H/Q depends on the velocity and position [21].…”