Since isokinetic exercise equipment has made determination of muscle performance with great accuracy objectively, athletic training at high velocity and scientific rehabilitation of the musculoskeletal injuries, it is being more widely used in sports and rehabilitation medicine.

The purpose of this study were to measure the strength, power and endurance of knee extensors and flexors by using the cybex Ⅱ isokinetic dynamometer in the healthy twenties, and to standardize the values obtained.

Twenty subjects were tested, 10 men and 10 women, between the aged of 21 and 28, and mean values of the body weight of 56.5 kg.

The results were as follows;

1) The mean peak torque of quadriceps at speed of 60°/second were 121.0±27.5 ft-lbs in male, and 67.6±5.3 ft-lbs in female. The mean of peak torque of hamstring at speed of 60°/second were 58.5±18.1 ft-lbs in male and 32.4±10.7 ft-lbs in female.

2) The mean torques of quadriceps and hamstring were decreased as the velocity of joint motion increased, and there were no significant differences of quadriceps and hamstring peak torques between dominant and nondominant sides.

3) In male, the ratio of quadriceps peak torque to body weight were 83.9%, and 40.3% for the hamstring. In female, the ratios of quadriceps and hamstrign peak torque to body weight were 56.3% and 27.2%, respectively.

4) The hamstring peak torque to quadriceps peak torque ratios at the speed of 60°/second were 48.8% in male and 47.1% in female.

5) In male, total works of quadriceps and hamstring were 1184.9±289.6 ft-lbs and 256.3±24737 ft-lbs, respectively and 605.0±142.5 ft-lbs for quadriceps and 182.8±99.8 ft-lbs for hamstring in female.

6) The endurance ratio of quadriceps were 65.0±17.3% in male and 72.6±23.8% in female, The Hamstring endurance ratio of male and female were 56.7±20.0% and 54.2±31.0% respectively.