Isokinetic Leg-Press Power-Force-Velocity Profiles Are Reliable in Male and Female Elite Athletes but Not Interchangeable With Vertical Jump Profiles

To evaluate the test-retest reliability of isokinetic leg-press power-force-velocity profile (P-F-v) parameters in male and female elite athletes. In addition, we determined the concurrent validity of leg-press against squat-jump (SJ) P-F-v parameters in task-experienced athletes. Methods: For test-retest reliability, 22 female and 23 male elite athletes (22.3 [4.1] y) with different sporting backgrounds conducted 3 isokinetic leg-press test sessions over 3 consecutive weeks. The testing consisted of bilateral leg extensions at isokinetic velocities of 0.1, 0.3, 0.7, and 1.2 m center dot s(-1). For concurrent validity, 13 ski jumpers (20.3 [3.3] y) were recruited to perform the isokinetic leg-press and SJ P- F-v profile tests using 5 predefined loading conditions of 0%, +20%, +40%, +60%, and +80% of body mass. Results: Relative and absolute reliability were acceptable for female (intraclass correlation coefficient >=.87 and coefficient of variation <= 6.5%) and male (intraclass correlation coefficient >=.89 and coefficient of variation <= 5.7%) elite athletes. In contrast, concurrent validity was insufficient, with correlations ranging from -.26 to.69 between isokinetic and SJ P-F-v parameters. Conclusion: Irrespective of sex, isokinetic leg-press P-F-v profiles provide reliable parameters. However, leg-press P-F-v profiles do not serve as a valid substitute for SJ P-F-v profiles. P-F-v parameter magnitudes are likely dependent on the constraints of the tested movement and testing device.