ACROSKI: TWO POLE GRIPS ARE BETTER THAN ONE FOR JUMPING

Abstract

1816 Principles of biomechanics once available only to researchers are now being used by coaches to improve athletic performance. When studying the existing guidelines for the length of poles used by Acro skiers, it was questioned whether the grip height above the snow would effect performance. The application of these biomechanical principles enabled a simple change in equipment to determine if they could improve athletes' jumps. Jumps are a key element of each Acro ski run, 25 - 50% of the score. By shortening the length of the ski pole, such that each elbow joint is at 90 degrees in the takeoff position, we found that athletes' could jump 11% higher than with traditional length Acro ski poles. This improvement results in jumps with greater amplitudes and speeds of rotation. Computer digitization was used to measure the height attained during a jump with both types of poles. Results from this study saw this increase in efficiency translate to increased height (0.7% to over 20%) for jumpers as well as increased rotational speeds. Nine National Team skiers from four countries volunteered for this study. Each skier performed 10 jumps; 5 with their traditional length poles and 5 with a shorter pole. There was a 5.5 ± 1.5 cm (mean ± SEM) increase in peak vertical height resulting from use of the shorter inside (lead) pole, which was statistically significant (p=0.004). Mean jump height for all subjects was 51.3 ± 4.7 and 56.8 ± 4.2 cm for the high and low grip, respectively. This represented an 11% improvement in performance on average. Nine out of ten of the athletes showed an improvement in the mean maximum height attained while using the shorter lead pole (range −5 to 28%). There appeared to be a direct relationship between the amount of change in jump height and the amount of change between the original pole length and the shorter pole which allowed a 90 degree bend of the elbow. Skiers who started with proportionately longer poles tended to have greater improvement when they switched to the shorter pole.