Practitioners have utilized sport specific alpine ski racing field tests for lower limb power assessment for many years. PURPOSE: The purpose of this study was to validate the alpine ski racing 90 s box jump field test with the 90 s Wingate.
METHODS: Elite alpine ski racers (n=15) were tested during their annual post-season physical testing combine. The box 90s box jump test was conducted on a foam plyo box of 0.45m x 0.75m x 0.9m (14 kg Plyosoft box from Escape Fitness). Subjects started at one side of the box and had to do a side jump and make contact with the top of the box and then jump back down to the other side back and forth. Final score being the total number of hits in 90 s. The Wingate test was conducted on a cycle ergometer (Ergomedic 894 E Monark). Subjects had to pedal with no resistance until they reached maximum RPM (about 5-10 s). The load (7.5% of bodyweight) was then manually dropped and subjects had to pedal at a maximal effort for 90 s. Wingate peak and mean power was measured in W and W/kg of bodyweight. Both tests were performed in a random order. Correlations between the different test results were calculated with a 2-tailed Pearson correlation analysis. Statistical significance was set at p<0.05. Subject characteristics are presented as means and standard deviations.
RESULTS: Results present significant (p<0.05) correlations between the total number of hits on the 90 s box jump and Wingate peak W (r=0.73), peak W/kg (r=0.68), mean W (r=0.77) and mean W/kg (r=0.79). Results also present significant correlations with the number of hits between the following time slots: 0-15 s mean W (r=0.49), 0-15 s mean W/kg (r=0.72), 15-30 s mean W (r=0.66), 15-30 s mean W/kg (r=0.71), 30-45 s mean W (r=0.59), 30-45 s mean W/kg (r=0.66), 45-60 s mean W (r=0.82), 45-60 s mean W/kg (r=0.77), 60-75 s mean W (r=0.83), 60-75 s mean W/kg (r=0.65), 75-90 s mean W (r=0.75) and 75-90 s mean W/kg (r=0.71). A predictive regression equation using the total hits during the 90s Box Jump Test was established, where mean W/kg = 0.055*Total Hits + 1.080 (r=0.79, p<0.01; Total Hits with mean W/kg).
CONCLUSIONS: The 90s box jump test is well correlated to the power output obtained with the Wingate test. Nonetheless, further research should include subjects at the national and international level in order to update the formula.