TIME ANALYSIS OF THE GIANT SLALOM TURN IN SNOWBOARDING

INTRODUCTION:Snowboarding is an increasingly popular sport, but it has been little studied so far, especially regarding the biomechanical characteristics (1). Most previous research concerned injury occurrence, the physiological profile of the snowboarding athletes (1) and dynamic variables characterizing the turn (2,3). Therefore, the aim of this study was to compare the turn technique of the snowboard giant slalom between elite and experienced recreational athletes, to improve the knowledge of performance factors and to provide suggestions to athletes and coaches. METHODS: Eight male snowboarders, four belonging to the Italian Snowboard National Team (EA, age 27±3.2y, height 1.80±0.10 m, mass 83.4±4.3 kg) and four experienced recreational athletes (RA, age 41.5±5.5 y, height 1.76±0.03 m, mass 89.0±12.2 kg) were analyzed during two performance on a snowboard slope (14 gates spaced at 21 m, 200m total descent). Eight wearable inertial and magnetic measurement units (APDM Opals, 128 Hz) were used for data collection. The sensors were fixed on sternum, sacrum, thigh, leg, toe of ski boot (right and left). Snowboarders were filmed when passing through the first 4 gates using a video camera (JVC full HD, 250hz) to compare the video recordings and the inertial sensor signal, and to define an algorithm to identifies automatically the transition of the gate and the change of the ski edge of all turns. These events were used to divide the turn in 4 phases: from change of ski edge to gate (T1) and from gate to change of ski edge (T2). Each event was identified for the backside-B and frontside-F turn, defining this way T1B, T2B, T1F, T2F respectively. RESULTS: Concerning time variables, EA showed shorter and more consistent times than RA in all turn phases (T1B 0.89±0.18s vs 0.99±0.11s, T2B 0.97±0.21s vs 1.53±0.50s, T1F 0.65±0.19s vs 1.23±0.3s, T2F 0.97±0.19s vs 1.31±0.22s), with significant differences (p<0.05) for all comparisons, with the exception of T1B. Also, the times of the total turn in B (0.92±0.19s vs 1.24±0.44s in EA and RA respectively) and in F (0.78±0.21s vs 1.25±0.24s in EA and RA respectively) were significantly shorter in EA than RA (p=0.03 and p=0.001 for B and F, respectively). T1 was shorter than T2 both in B and in F, but this difference was not statistically significant. CONCLUSION: As expected, EA completed all the phases of the turn more quickly than RA. This difference was noticeable during the F turn, especially in the T1 phase, more evidently than in B. In fact, as confirmed by the coaches of the Italian National Team, to perform an optimal F technique, highly developed technical skills are needed. Moreover, EA showed, for all variables, a lower variability and a higher repeatability than RA. The results of this study suggest that, in attempt to improve the performance, it is overall necessary to enhance F technical skills. 1) Vernillo et al., Frontiers in Physiology (2018) 2) Hirose et al., Procedia Engineering, (2012). 3) Kondo et al., Procedia Engineering, (2014).