The efficacy of isokinetic, isometric and vertical jump tests in exercise science

This research examined the efficacy of several tests of muscular strength and power in their capacity to be related to performance, their ability to effectively discriminate between individuals of different performance levels and their sensitivity in detecting training induced changes to performance. Thirty healthy active subjects performed the following maximal tests of muscular function: (1) Vertical jump; (2) Isokinetic knee extension at 1.05, 3.14 and 5.24 rads s-1; and (3) Isometric rate of force development. Performance was assessed by the peak power output achieved on a cycle test. In addition, subjects participated in a 10 week resistance training program. The isokinetic and vertical jump tests were significantly related to performance (r = 0.5-0.73) and could be used to discriminate between subjects of differing performance levels. However, the isometric rate of force development test was an ineffective assessment modality. None of the tests were able to effectively monitor training induced changes in performance, as evidenced by non-significant correlations between the pre- to post-percentage changes in cycling performance and the test variables. Consequently, alterations to training programs for athletes should be based on changes in actual performance, as opposed to muscular function tests.