Isokinetic knee extensor strength and functional performance in healthy female soccer players

The aims of this study were to determine the relationship between isokinetic knee extensor muscle strength at 60 degrees/s and 180 degrees/s and five functional performance tests (one-leg-hop, triple-jump, vertical-jump, one-leg-rising and square-hop), to determine the relationship between the five different functional performance tests and to present normative data and limb symmetry index concerning healthy female soccer players. In total 101 female soccer players (X = 20.3 years) were tested. A limb symmetry index, using weak/strong leg, varied from 83.9 to 96.3 in the tests. Between the functional performance tests there were in general correlations of r = 0.4-0.8 (P < 0.001). A correlation of r = 0.77 (P < 0.001) was obtained between one-leg-hop and triple-jump. No differences were found between the right and the left leg or the dominant and the non-dominant leg. Using linear regression models corrected for body weight, height and age, there were low correlations between the isokinetic strength measurements and the functional tests. It is not recommended using functional performance testing and isokinetic testing interchangeably.