Determination of forces in alpine skiing and snowboarding: Validation of a mobile data acquisition system

摘要

The aims of this study were (1) to analyse the influence of temperature on the accuracy of a single 3D-dynamometer, (2) to establish the accuracy of a force measurement system that utilizes 3D-dynamometers, and (3) to compare forces measured by pressure insoles and by 3D-dynamometers. Temperature dependence was assessed on a single dynamometer at three different temperatures (23degC, 0degC, -10degC) in a cooling chamber. The relative measurement error was determined in the laboratory with the system mounted on alpine skis and on a snowboard. The forces measured by pressure insoles and by 3D-dynamometers were compared in tests on snow. One skier was used in this part of the study. The average measurement error of a single dynamometer increased from 0.2% to 0.9% when the temperature changed from +23degC to -10degC. At low forces (<292 N), the average measurement error was 4.6% and 3.3% for the ski and snowboard system, respectively. At higher forces (>292 N), the average measurement error decreased to 0.3% and 0.4% for the ski and snowboard system, respectively. The average measurement error for 3D torques ranged from 4.0 to 8.3% for the ski, and from 2.4 to 8.5% for the snowboard system. The deviation of the calculated point of force application from its reference was 1.4 mm (medio-lateral) and 8.8 mm (antero-posterior) for the ski, and 2.7 mm and 10.4 mm for the snowboard system. In general, forces determined by insoles were on average 21% (outer ski) and 54% (inner ski) lower than forces measured by 3D-dynamometers. The similarity in force-time characteristics of the insoles compared with the 3D-dynamometer was high. In conclusion, the temperature had little impact on the measurement accuracy of 3D-dynamometers. The measurement error of 3D-dynamometers decreased with an increase in forces. The accuracy of 3D-dynamometers was similar to that shown in previous studies of measuring systems used in laboratory tests. The 3D-dynamometers increased the standing height by