Total work changes at different angular velocities during isokinetic exercise

The purposes of this study were (1) to see the change of total work during isokinetic exercise and (2) to suggest more advanced methods of measuring muscular endurance through considering not only the number of repetitions, but also exercise duration. The subjects were 54 healthy students who performed continuous maximal isokinetic knee flexion and extension until their total work per time reached 50% of their maximal total work. Total work sums, exercise duration in seconds, and the number of repetitions were compared with reference to subject gender, angular velocity, and muscle group. The relationships between total work sum, duration and number of repetitions, and thigh circumference plus leg length were computed. The results showed the total work sums differed greatly from muscle group to muscle group and with different angular velocities. The duration in seconds and the number of repetitions differed only at higher angular velocity. These results suggest that measures of endurance should be included along with measures of total work when isokinetic studies are done. When isokinetic exercise is performed, measures of endurance in seconds are more accurate at an angular velocity of 60 degrees per second and numbers of repetitions are more accurate at an angular velocity of 180 degrees per second.