It has been widely reported that muscle activity increases when skiing on wide (>90 mm underfoot width) powder skis compared to skiing on slalom regulation (~65 mm underfoot width) skis on groomed runs. Wide skis were originally designed to be skied in powder snow conditions. In recent years, it has been observed that skiers have been using the wide skis for all conditions including groomed snow. A previous study at Montana State University reported that the use of wide skis on groomed snow may create an additional lever arm from the edge of the binding plate to the ski edge. That study showed a smaller edge angle and more skidding while skiing the wider ski as compared to a narrow ski (<75 mm underfoot). The increased forces and torque may also be cause for concern of fatigue and possible injury.
Additionally, it is unclear how consistent skiers are from turn to turn when skiing through standardized gated turns. Thus, preliminary work will use elite level adult skiers to determine the reliability of turn characteristics throughout multiple runs. Turn characteristics can be assessed through measuring edge angle, edge angle per percentage of turn, and turn radius. This study will use expert level adult and junior ski racers to compare muscle activity and turn characteristics from skiing wide skis and narrow regulation slalom skis on groomed terrain. Junior racers are commonly seen using wide skis while skiing outside of the racing and training area. A major concern is that junior skiers may be developing a technique of muscle activity patterns when skiing wide skis that may be different than the technique necessary for racing. This could lead to poor performance, increased fatigue, or injury while racing.
The questions to be investigated are: 1) Is there a significant kinematic and muscle activity difference when skiers are using wide skis compared to regulation slalom skis in free skiing and standardized turns? 2) Are there differences in muscle activation patterns between elite adult skiers and junior racers?
The average vertical ground reaction force (top) and the center of pressure (fore-aft, middle; medial-lateral, bottom) for two ski conditions during the four phases of an alpine ski turn.
The average knee angle for two conditions during during the four phases of an alpine ski turn.
The hip and knee joint moments for two conditions during a double ski turn.