SELF-PREFERRED INITIAL POSITION COULD BE A VIABLE ALTERNATIVE TO THE STANDARD SQUAT JUMP TESTING PROCEDURE

The purpose of this study was to compare both the magnitude and reliability of different variables (knee angle, squat depth, jump height [Hmax], maximum force [Fmax], and maximum power [Pmax]) between the standardized squat jump (SJ) and the SJ performed from the self-preferred position. Eleven team handball players (age: 19.5 +/- 1.1 years; height: 1.88 +/- 0.06 m; and body mass: 82.1 +/- 8.7 kg) and 13 physically active students (age: 20.5 +/- 0.9 years; height: 1.81 +/- 0.06 m; and body mass: 76.6 +/- 6.6 kg) were evaluated on 2 sessions during the standardized SJ (knee angle fixed at 90 degrees) and the self-preferred SJ (self-selected knee angle to maximize Hmax). Two blocks of both 3 standardized SJ and 3 self-preferred SJ were performed on the first session, whereas only 1 block was performed in the second session. The squat depth was smaller for the self-preferred SJ, whereas the knee angle, Fmax, and Pmax were higher for the self-preferred SJ (p < 0.025). The magnitude of Hmax did not significantly differ between both jump types. Most importantly, the reliability of the mechanical outputs (Hmax, Fmax, and Pmax) was generally higher for the self-preferred SJ (9 of 12 comparisons), whereas only in 2 of 12 comparisons the reliability was meaningfully higher for the standardized SJ. No differences were observed between presumably more (handball players) and less skilled individuals (physically active subjects). These results suggest that the self-preferred SJ should be recommended over the standardized SJ (90 degrees knee angle) because it is not only quicker and more ecologically valid, but could also provide the performance variables with higher reliability.