The ability of tests of muscular function to reflect training-induced changes in performance

We examined the ability of isokinetic and isoinertial tests of muscular function to track training-induced changes in performance. Subjects completed the following tests before and after training: (1) two isoinertial tests using concentric and eccentric actions; (2) isokinetic knee extension at two velocities; and (3) a one-repetition maximum squat. Further, a 40 m sprint and 6 s cycle test were conducted as measures of athletic performance. The subjects were split into a weights group, which performed heavy squats, and a control group. The results showed that training significantly enhanced sprint time by 2.2%, and the improvement in cycle performance (9%) approached significance (P = 0.09). However, apart from the squat, no measure of muscular function significantly changed because of training. Furthermore, there was no relationship between the training-induced changes in performance and the training-induced changes in the isokinetic and isoinertial tests. The results suggest that tests of muscular function cannot be used to monitor training-induced changes in performance. We considered this to be due to the large degree of variance unaccounted for in the relationship between the scores on tests of muscle function and performance. Therefore, the effectiveness of training should be based on changes in performance rather than changes in test scores of muscle function.