INTRODUCTION: In mogul skiing 50% of final points of a competition run are based on the points given by judges related to turning technique. The remainder of the points comes from run time (25%) and Jumps (25%). Thus, appropriate turning technique combined with fast running time are very important factors for success in mogul skiing. The purpose of this study was to determine angular changes of knee joint and EMG-activity during the mogul skiing turns among top-level freestyle skiers. METHOD: Six male freestyle skiers competing in either on World Cup or Europa Cup level were the subjects of this study. They executed two to three mogul skiing performances with competition-Iike effort. EMG-activities of the front thighs, back thighs, and calf muscles were measured with "EMG-pants" by Mega Electronics during the run. Textile electrodes embedded into the pants measured EMG-activity with a sampling frequency of 1000 Hz (Finni et al. 2007). Angular changes of the knee joints were measured with twin axis goniometers (Biometrics Ltd.) for both legs. All data was recorded in a portable Biomonitor ME6000 measuring unit attached to the waist of the skiers. RESULTS: Results for turn times, knee angles, and EMG-activities are presented in Table 1. EMG-activities are presented in percent values separately for extension and flexion phases (derived from knee angles) as portions of the total activity during one turn. DISCUSSION: Changes in knee angles were slightly lower, but max-values higher than in the previous studies (Berg et al. 1999), All skiers differed significantly from each other in turn times, knee angles, and EMG-activity expressed as flexion/extension ratio. The most experienced, Skier 1, had noticeably faster flexion phases and higher relative EMG-activity of back thighs and calves in turns than the other two skiers. CONCLUSION: In top-level mogul skiing, an athlete has to work effectively with back thighs and calves (gastrocnemius region) in flexion phases in order to achieve high running speed and balanced Position. Total change in knee angles during one turn is approximately 50-60°.
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