INTRODUCTION: Analysis of biomechanical Parameters in cross-country (XC) skiing is a challenging task to improve performance (Andersson et al 2010). Methods for movement analysis are often limited to laboratory situations, have limited time capacities and are expensive and therefore not available in routine training. Especially in young athletes, systems which can allocate relevant Information in short time under functional conditions would give an improvement in training. Therefore our goal was to adapt a system based on inertial sensors and already tested in gait analysis for the use in XC skiing training with a special focus on the integration of pole force measurements. METHOD: A strain gauge system for measuring axial forces (Velomat, Kamenz, Germany) was integrated into an aluminum adapter (length 145 mm, diameter 14.5 mm, weight 160 g). This adapter can be integrated in every pole tube with corresponding diameter directly under the grip. An inertial sensor system (Humotion, Münster Germany) with the capacity to record 3D-acceleration and gyroscopic signals was selected for the data acquisition. Two channels of the sensor are offered for the input of external analogous signals which were in this case used for the pole forces. The inertial sensor system is fixed with an elastic bell at the lower spine at level L3- L5. The weight of the sensor is 30 grams. All Signals were stored onboard on a microchip with a sampling frequency of 100 Hz (optional up to 400Hz). Depending on the capacity of the battery a recording time of 24 hours is possible. The recording of the data sampling is started automatically when the system is disconnected from the PC and stops when it is reconnected to the PC. All signals are stored in ASCII formal for further analysis. RESULTS and Discussion: In the diagram a section out of a 11 min trial represents the signal characteristic of V2 skating. The initial pole forces are in good accordance with the maxima and minima in the acceleration signals as well within the gyroscope. It could have been shown, that the system is applicable for recording pole forces as well as kinematic parameters. Like in gait analyzing characteristics in the acceleration as well as in the gyroscopes are observed. This supports the possibility that different techniques (skating, classic) can be recorded under functional conditions in real training situation of athletes. Further advantage is that the system is light and does not disturb the athlete in normal training situations. CONCLUSION: The possibility of long term recording is especially beneficial for XC-skiing. Another improvement might be the integration of biofeedback by using the amplitude and impulse of the pole forces or temporal aspects. Based on this system further studies should be carried out to answer questions concerning the correlation between technical aspects in different XC-skiing techniques based on the recording of inertial signals and other biomechanical signals.
© Copyright 2010 Book of Abstracts. 5th International Congress on Science and Skiing, Dec. 14 - 19, 2010, St. Christoph am Arlberg. Published by University of Salzburg, Interfakultärer Fachbereich Sport- und Bewegungswissenschaft/USI. All rights reserved.