This study introduces an inertial measurement unit-based measurement system for resolving the dynamic lean angle of a ski pole during double poling while cross-country skiing. The measurement system estimates both the pole lean angle and pole-terrain contact events. Reported are results from 20 trials providing validated estimates of ski pole lean angle and the timing of pole plant and pole lift events. The pole lean angle is estimated from a complementary filter that fuses estimates of orientation from the embedded accelerometer and angular rate gyro. Validation follows from comparison with video capture measurements. Bland-Altman analysis showed agreement between the two measurement modalities with less than 5% bias in the mean differences (relative to the lean angle range of motion). Companion correlation analysis confirms strong correlation ( r = 0.99 ) between the inertial measurement unit and video-estimated lean angles and with mean root-mean-square errors below 4.5 • .Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
The purpose of this paper is to present the development of a simple multibody dynamic model matching the observed movements of the center of mass of a skier performing the skating technique in cross-country skiing. The formulation of the equation of motion was made using the Euler–Lagrange equations applied to a multibody tree-type system in three dimensions. The description of the lower limb of the skier and the ski was completed by employing three bodies, one representing the ski, and two representing the natural movements of the leg of the skier. This simple model is able to show an approximation of the movement of the center of mass of the skier and its velocity behavior allowing to study the effect of the key parameters used to build the model.
In this paper, a three-dimensional multibody dynamic model of a cross-country skier is developed and presented where a single propulsion phase is modeled to obtain the kinetic parameters involved in the movement. A professional Olympic-level skier performed the skating technique without poles in a ski tunnel under controlled conditions and on an incline plane. Then, with the use of a force acquisition system attached to the ski bindings and a motion capture system set on site, the leg resultant forces and the movement of specific points of the skier’s lower body were acquired. The data obtained from the motion capture system was used as the prescribed kinematic input data in the multibody model and the measured force was used later as a comparison parameter with the results of the simple model. After simulating the technique, the calculated propulsion forces seem to be in agreement with those measured in the field.
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