KINEMATIC ANALYSIS OF AN INDOOR SKI JUMPING SIMULATOR

  • P.M. Sustrich
  • P.M. Gallagher
  • D.M. Drewlinger

Abstract

Ski jumping can be divided into three separate phases for biomechanical analysis: inrun, take-off and flight. Because of the technicality of the sport, hundreds of hours must be spent just practising the take-off. Therefore, a need exists to develop an effective simulator where athletes can practice the timing and biomechanical aspects of the take-off year-round. The US Olympic Development Team (USODT) has assembled such a simulator which is constructed of wood and steel tracking. This study is the first stage of a plan to determine the effectiveness of an indoor ski jumping simulator. The purpose of this stage was to describe the kinematics involved during the take-off phase on an indoor simulator. The second and third stages will consist of a kinematic and kinetic comparison of simulated ski jumping to on-snow jumping. The take-off has been regarded as the most critical aspect of ski jumping due to the importance of timing and the biomechanical positioning of the jumper. Therefore, only the take-off phase was analyzed. The variables examined in this study were take-off velocity (TOV), angle of attack (AOA), angular acceleration of the hip and knee (AAH,AAK), vertical acceleration of the centre of gravity (VAC), shank angle (SHA), and horizontal displacement of the centre of gravity with respect to the ankle (HDC);because, according to Campbell (1990), these variables best describe a jumper's performance at take-off. During the take-off phase, the skier's HDC should continue to increase in the direction of movement. Video data, collected at 60 Hz, were analyzed for seven male USODT members. Three trials were performed by each subject. Means and standard deviations for each of the variables are presented as follows. Additionally, it was found that the HDC positively increased throughout the takeoff. Because of the similarities between these findings to those previously reported, it was concluded that this apparatus has the potential to simulate on-snow jumping.
Section
Coaching and Sports Activities