Validation of the alpine skiing 90 seconds box jump field test and prediction of power output.

Abstract

The purpose of this study was to validate the alpine ski racing 90 s box jump field-test (BJ90) with the 90 s Wingate test (W90). Fifteen elite alpine ski racers were tested on the BJ90 (0.45 m × 0.75 m × 0.9 m) and the W90 (Ergomedic 894 E Monark; Monark AB, Varberg, Sweden) test in a random order. The number of hits on the BJ90 was written down every 15 s and for the W90 the load (7.5% of body weight) was manually dropped once the subjects reached maximum RPM without resistance. Correlations and partial correlations were calculated with a 2-tailed Pearson correlation analysis. A stepwise forward regression analysis was also performed. Results present significant (P<0.05) correlations and partial correlations adjusted for body weight between the total number of hits on the BJ90 and W90 peak W, peak W/kg, mean W and mean W/kg as well as with the number of hits and W90 Mean W and mean W/kg between each 15 s time slot. A linear regression predictive equation for mean relative power (W/kg) generated from the BJ90 was established: mean relative power (W/kg)=0.055*total hits+1.080 (r=0.79, P<0.001; total hits with mean W/kg). A stepwise forward regression equation for mean absolute power (W) generated from the BJ90 was also established: mean absolute power (W)=2.305*number of hits+5.081*body weight in kg-1 -169.8 (R=0.964, P<0.001, SEE=23.56). Practitioners could use the BJ90 to assess alpine skiers lower body power as previous research showed that both are correlated with performance and are able to discriminate skier level.