Skier-ski system model and development of a computer simulation aiming to improve skier's performance and ski

Background. Based on personal experience of ski teaching, ski training and ski competing, we have noticed that some gaps exist between classical models describing body-techniques and actual motor acts made by performing athletes. The evolution of new parabolic shaped skis with new mechanical and geometric characteristics increase these differences even more. Generally, scientific research focuses on situations where skiers are separated from their skis. Also, many specialized magazines, handbooks and papers print articles with similar epistemology. In this paper, we describe the development of a three-dimensional analysis to model the skier-skis' system. We subsequently used the model to propose an evaluation template to coaches that includes eight techniques and three observable consequences in order to make objective evaluations of their athletes' body-techniques. Once the system is modeled, we can develop a computer simulation in the form of a jumping jack, respecting degrees of freedom of the model. We can manipulate movement of each body segment or skis' gears' characteristics to detect performance variations. The purpose of this project is to elaborate assumptions to improve performance and propose experimental protocols to coaches to enable them to evaluate performance. This computer simulation also involves board and wheeled sports.

Methods. Eleven elite alpine skiers participated. Video cameras were used to observe motor acts in alpine skiers in two tasks: slalom and giant slalom turns. Kinematic data were input into the 3D Vision software. Two on-board balances were used to measure the six components of ski-boots→skis torques. All data sources were then synchronized.

Findings. We found correlations between force and torque measurements, the progression of center of pressure and the eight body-techniques. Based on these results, we created a technological model of the skier-ski system. Then, we have made a reading template and a model to coach young alpine skiers in clubs and world cup alpine skiers and, we have obtained results demonstrating the usefulness of our research.

Interpretation. These results suggest that it is now possible to create a three-dimensional simulator of an alpine skier. This tool is able to compare competitors' body-techniques to detect the most performing body-techniques. Additionally, it is potentially helpful to consider and evaluate new techniques and ski characteristics.