ISOMETRIC AND ISOKINETIC MEASUREMENT OF HAMSTRING AND QUADRICEPS STRENGTH

This study evaluates quadriceps strength at varying movement velocities in a group of healthy subjects. Specific objectives included (1) investigating the effect of angular velocity on peak torque (PT) (2) investigating the effect of angular velocity on joint angle at peak torque (JAPT) and (3) evaluating whether the use of a relatively new isokinetic testing device yields new insights to previously accepted relationships between angular velocity and PT or JAPT. Twenty healthy subjects were tested for isometric and isokinetic knee extension and flexion strength on a LIDO Active Isokinetic Rehabilitation System at velocities of 0-degrees, 60-degrees, 120-degrees, and 180-degrees/sec. Isometric PT (0-degrees/sec) was found to be highly correlated with isokinetic PT for both extensors and flexors at all velocities (r = .88-.93, p < .01). PT declined significantly as angular velocity increased for both extension (p < .01) and flexion (p < .05). A relationship between isometric and isokinetic JAPT was significant for extension only at 60-degrees and 180-degrees/sec (r = .48-.52, p < .05). These results indicate that knee isometric and isokinetic PT as measured on the LIDO Active system are highly related for both extension and flexion. PT declined as isokinetic angular velocity increased. Isometric and isokinetic JAPT are significantly related only for extension.