EFFECTS OF THE DIFFERENT POSITION OF THE FEET IN SLALOM AND FREESTYLE SNOWBOARDING ON MUSCLE ACTIVITY OF KNEE EXTENSORS

Abstract

It was the purpose of this study to investigate the effect of the different position of the feet in slalom compared to freestyle snowboarding, on muscle activity of the m.rectus femoris and the m.vastus medialis when using the up-unweighting technique. Three male snowboard instructors participated in the investigation. They were experts in both snowboard styles. With a portable recorder EMG signals from the m.vastus medialis and m. rectus femoris were recorded. The knee extensors were more active in backside positions compared to frontside positions. The m. rectus femoris seems to fulfil a role in the stabilisation of the knee joint in backside positions. The m.vastus medialis seems to be important in the up-unweighting movement itself by performing a knee extension in backside position.