Reliability of measurements of concentric and eccentric isokinetic loading.

The purpose of this study was to assess the reliability of a method for testing peak torque and work output of the knee extensor muscle during concentric and eccentric loading at three velocities of exercise (60 degrees, 120 degrees, and 180 degrees/sec). Fourteen healthy men (23-32 years of age) performed exercises of the quadriceps femoris muscles during concentric and eccentric loading, with a five-second pause between each contraction. Three different tests were performed on different occasions. The first exercise session was a practice session, and the next two sessions were established to collect data in a test-retest format. Peak torque and work were measured for the two testing sessions. The results of this study demonstrated that with a very specific protocol, the reliability of concentric peak torque and work measurements was excellent at 60 degrees and 120 degrees/sec and good at 180 degrees/sec. In contrast, reliability of eccentric peak torque and work measurements was good at 120 degrees and 180 degrees/sec but low at 60 degrees/sec.