The isometric torque of the knee flexor and extensor muscles were measured for 6 seconds at three knee joint positions(30°, 45°, 60°) in 60 normal, healthy men in three age groups from 22 to 49 years, using the Isokinetic Rehabilitation & Testing System(Model No. Cybex340).

The peak torque, the time to peak torque, and torque at each second were measured for each contraction. In addition, heart rate and blood pressure were recorded simulatneously at rest and immediately following contraction at 1 and 3 minutes.

Age had a significant positive correlation with mean peak isometric torque for both knee extensors and flexors at all examined joint angles except knee extensors at 30°(p<0.01). The onset time to peak torque had a significant positive correlation with age for only knee extensor(p<0.01).

The mean increment ratio was 21.1% for systolic blood pressure and 10.4% for diastolic pressure, and, in the younger ages, the increment of diastolic pressure was significantly lower than that of the older ages(p<0.01).

The mean heart rate increased promptly by 48.9% of its resting level and the increment of the youngest group was significantly higher than that of the older group