Effects of speed, hip and knee angle, and gravity on hamstring to quadriceps torque ratios

Abstract

The purpose of this study was to determine the effects of speed, hip angle, knee angle, and gravity on hamstring to quadriceps (H/Q) torque ratios. Eighteen healthy college-aged men performed three maximal-effort knee extension and flexion repetitions on a Cybex II® isokinetic dynamometer at speeds of 15 and 90°/sec. Hamstring and quadriceps torques were measured at 15, 30, 45, 60, 75, and 90°of knee flexion and at the angles at which peak torque occurred. These torques were also measured at 5 and 120°of hip flexion. H/Q torque ratios were calculated with these torques, both corrected and uncorrected for gravitational effects. Analysis of variance revealed that gravity-corrected ratios decreased with increased knee angles from 15 to 60°. The higher hip angle at each speed produced higher ratios at knee angles between 30 and 90°. The effect of speed on ratios was variable and interacted with hip and knee angle. Correction for gravity reduced the ratios at all knee angles except 90°. H/Q torque ratios at selected knee angles ranged from 0.20 to 2.00, differed from H/Q peak torque ratios 40% of the time, and did not always correlate highly with H/Q peak torque ratios (range: r = 0.50-0.90). Thus, H/Q peak torque ratios were not indicative of H/Q torque ratios at selected knee angles. Thus, knee angle-specific H/Q torque ratios may provide different, and perhaps more useful, information about hamstring and quadriceps function than do H/Q peak torque ratios.