Optimal isokinetic loads and velocities producing muscular power in human subjects

The torque values of the quadriceps muscles of 16 college football players were tested by means of an isokinetic dynamometer in order to determine the optimal loads and velocities producing muscular power. The men were tested at velocities ranging from 5 to 25 rpm and throughout a range of knee extension between the positions of 85 degrees to 50 degrees of knee flexion. Isometric measures were also recorded at corresponding angles. The muscular torque values recorded isokinetically at the various velocities were then compared to the isometric forces at the corresponding angles of knee extension to ascertain the arithemtic proportion of isokinetic to isometric torque which produced maximum muscular power. The results indicated that the proportionate values of isokinetic to isometric torque and isokinetic velocities which produced maximum power were not directly comparable to similar loads and velocities found in vitro. The weight of the leg may have contributed to submaximal isometric recordings, thus resulting in higher proportionate values of isokinetic to isometric force. Changes in these values as the knee was extended were deemed to be a result of variance in the isometric torque since the isokinetic torque stayed relatively constant throughout the range of movement. The data suggested that a plateau of isokinetic torque may have been reached in the production of maximum power. Maximum isokinetic torque values tended to shift to more extended joint positions as the speed of knee extension increased. This shift may have been due to the momentum of the leg during the faster isokinetic speeds overcoming some of the inertia of the weight of the leg as it was extended.