INTRODUCTION: Ten years ago, sprint skiing events were introduced into the World Ski Championships, and subsequently, some skiers have tried to adapt their cross-country skiing technique to the higher racing speeds attained during sprint skiing. The racing speed using the double-poling technique is high, and many athletes use double-poling technique when they want to accelerate or when they are close to the finish line (Stöggl, et al., 2006). Thus, it is important that athletes keep the high level of the racing speed. However, no study could be found elucidating a relationship between the racing speed and the time course changes of kinematics and kinetics during double-poling technique. The purpose of this study was to examine time course changes of the kinematics and the kinetics during double poling techniques in cross-country sprint skiing. METHOD: Five subjects performed 3 min maximal double poling on an oval track (320 m). Measured kinematic parameters were the mean velocity, cycle length, cycle rate, duration over one cycle, which consists of poling (0% - 30% of one cycle) and gliding (30% -100% of one cycle) phases. The segment angles were measured for the upper and forward arms, trunk, thigh, shank, foot, pole from the horizontal plane. Distance from the most proximal edge of the foot to the pole contact point, which is defined here as pole contact length, was also calculated. For the kinetic parameters, the peak and mean forces and Impulse of poles were analyzed. RESULTS: The velocity, cycle rate and peak and mean pole forces decreased significantly at 3rd lap compared with 1st lap of the round. In contrast, duration of the poling and gliding phases and impulse of pole and poling angle increased significantly at 3rd lap compared with 1st lap (p<.05). There was no significant difference in the cycle length and pole contact length among laps (p<.05). Thigh angle was greater, and shank and foot angles were less at 3rd lap than at 1st lap in poling phase (p<.05). During gliding phase, foot and thigh angles were greater and shank angle was less at 3rd lap than at 1st lap (p<.05). DISCUSSION: In poling phase, thigh angle was greater and lower limb and foot angles were less, indicating position while one cycle. In glide phase, foot and thigh angles were greater and shank angle was less indicating decreased flexing and extending action. CONCLUSION: The aim of this study was to examine time course changes of the kinematics during double poling technique. Double poling technique during sprint skiing was changed to erect standing position of the body and decreased flexing and extending action of legs with time course.
© Copyright 2010 Book of Abstracts. 5th International Congress on Science and Skiing, Dec. 14 - 19, 2010, St. Christoph am Arlberg. Published by University of Salzburg, Interfakultärer Fachbereich Sport- und Bewegungswissenschaft/USI. All rights reserved.