A New Concept For Isokinetic Hamstring: Quadriceps Muscle Strength Ratio

Abstract

Conventionally, the hamstring:quadriceps strength ratio is calculated by dividing the maximal knee flexor (hamstring) moment by the maximal knee extensor (quadriceps) moment measured at identical angular velocity and contraction mode. The agonist-antagonist strength relationship for knee extension and flexion may, however, be better described by the more functional ratios of eccentric hamstring to concentric quadriceps moments (extension), and concentric hamstring to eccentric quadriceps moments (flexion). We compared functional and conventional isokinetic hamstring: quadriceps strength ratios and examined their relation to knee joint angle and joint angular velocity. Peak and angle-specific (50 degrees, 40 degrees, and 30 degrees of knee flexion) moments were determined during maximal concentric and eccentric muscle contractions (10 degrees to 90 degrees of motion; 30 and 240 deg/sec). Across movement speeds and contraction modes the functional ratios for different moments varied between 0.3 and 1.0 (peak and 50 degrees), 0.4 and 1.1 (40 degrees), and 0.4 and 1.4 (30 degrees). In contrast, conventional hamstring:quadriceps ratios were 0.5 to 0.6 based on peak and 50 degrees moments, 0.6 to 0.7 based on 40 degrees moment, and 0.6 to 0.8 based on 30 degrees moment. The functional hamstring:quadriceps ratio for fast knee extension yielded a 1:1 relationship, which increased with extended knee joint position, indicating a significant capacity of the hamstring muscles to provide dynamic knee joint stability in these conditions. The evaluation of knee joint function by use of isokinetic dynamometry should comprise data on functional and conventional hamstring:quadriceps ratios as well as data on absolute muscle strength.

Desempenho muscular, dor, rigidez e funcionalidade de idosas com osteoartrite de joelho

“…The relation between maximum isokinetic torque of the hamstring muscles and maximum isokinetic torque of the quadriceps muscle (H/Q ratio) is a parameter commonly used to describe the muscle balance of the knee joint. 18 The expected value of the H/Q ratio for asymptomatic adults, evaluated by the isokinetic dynamometer, tends to be from 60% to 76%, varying with the angular speed. 19 However, data on this percentage in the elderly population are scarce.…”

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].…”

“…For example, Aagaard et al [14,21] demonstrated the potential 1:1 hamstring to quadriceps strength relationship for fast knee extension, reflecting a significant functional capacity of the hamstring muscles for providing muscular stability at the knee joint. In contrast, too low values of the functional H/Q indicate an imbalance in muscle strength between the agonist and the antagonist, and may contribute to a greater risk of anterior cruciate ligament (AcL) injury.…”

“…In isokinetic tests, the H/Q depends on the velocity and position [21]. The correct H/Q indicates the muscle strength balance between the hamstrings and quadriceps [15,17,19,20,22].…”