Aurélien Patoz1, Thibault Lussiana2, Bastiaan Breine3, Cyrille Gindre4, Davide Malatesta5. 1. Institute of Sport Sciences, University of Lausanne, Lausanne, 1015, Switzerland; Research and Development Department, Volodalen Swiss Sport Lab, Aigle, 1860, Switzerland. Electronic address: aurelien.patoz@unil.ch. 2. Research and Development Department, Volodalen Swiss Sport Lab, Aigle, 1860, Switzerland; Research and Development Department, Volodalen, Chavéria, 39270, France; Research Unit EA3920 Prognostic Markers and Regulatory Factors of Cardiovascular Diseases and Exercise Performance, Health, Innovation Platform, University of Franche-Comté, Besançon, France. 3. Research and Development Department, Volodalen Swiss Sport Lab, Aigle, 1860, Switzerland; Department of Movement and Sports Sciences, Ghent University, Ghent, 9000, Belgium. 4. Research and Development Department, Volodalen Swiss Sport Lab, Aigle, 1860, Switzerland; Research and Development Department, Volodalen, Chavéria, 39270, France. 5. Institute of Sport Sciences, University of Lausanne, Lausanne, 1015, Switzerland.
Abstract
BACKGROUND: While running, the human body absorbs repetitive shocks with every step. These shocks can be quantified by the peak vertical ground reaction force (Fv,max). To measure so, using a force plate is the gold standard method (GSM), but not always at hand. In this case, a motion capture system might be an alternative if it accurately estimates Fv,max. RESEARCH QUESTION: The purpose of this study was to estimate Fv,max based on motion capture data and validate the obtained estimates with force plate-based measures. METHODS: One hundred and fifteen runners participated at this study and ran at 9, 11, and 13 km/h. Force data (1000 Hz) and whole-body kinematics (200 Hz) were acquired with an instrumented treadmill and an optoelectronic system, respectively. The vertical ground reaction force was reconstructed from either the whole-body center of mass (COM-M) or sacral marker (SACR-M) accelerations, calculated as the second derivative of their respective positions, and further low-pass filtered using several cutoff frequencies (2-20 Hz) and a fourth-order Butterworth filter. RESULTS: The most accurate estimations of Fv,max were obtained using 5 and 4 Hz cutoff frequencies for the filtering of COM and sacral marker accelerations, respectively. GSM, COM-M, and SACR-M were not significantly different at 11 km/h but were at 9 and 13 km/h. The comparison between GSM and COM-M or SACR-M for each speed depicted root mean square error (RMSE) smaller or equal to 0.17BW (≤6.5 %) and no systematic bias at 11 km/h but small systematic biases at 9 and 13 km/h (≤0.09 BW). COM-M gave systematic biases three times smaller than SACR-M and two times smaller RMSE. SIGNIFICANCE: The findings of this study support the use of either COM-M or SACR-M using data filtered at 5 and 4 Hz, respectively, to estimate Fv,max during level treadmill runs at endurance speeds.
BACKGROUND: While running, the human body absorbs repetitive shocks with every step. These shocks can be quantified by the peak vertical ground reaction force (Fv,max). To measure so, using a force plate is the gold standard method (GSM), but not always at hand. In this case, a motion capture system might be an alternative if it accurately estimates Fv,max. RESEARCH QUESTION: The purpose of this study was to estimate Fv,max based on motion capture data and validate the obtained estimates with force plate-based measures. METHODS: One hundred and fifteen runners participated at this study and ran at 9, 11, and 13 km/h. Force data (1000 Hz) and whole-body kinematics (200 Hz) were acquired with an instrumented treadmill and an optoelectronic system, respectively. The vertical ground reaction force was reconstructed from either the whole-body center of mass (COM-M) or sacral marker (SACR-M) accelerations, calculated as the second derivative of their respective positions, and further low-pass filtered using several cutoff frequencies (2-20 Hz) and a fourth-order Butterworth filter. RESULTS: The most accurate estimations of Fv,max were obtained using 5 and 4 Hz cutoff frequencies for the filtering of COM and sacral marker accelerations, respectively. GSM, COM-M, and SACR-M were not significantly different at 11 km/h but were at 9 and 13 km/h. The comparison between GSM and COM-M or SACR-M for each speed depicted root mean square error (RMSE) smaller or equal to 0.17BW (≤6.5 %) and no systematic bias at 11 km/h but small systematic biases at 9 and 13 km/h (≤0.09 BW). COM-M gave systematic biases three times smaller than SACR-M and two times smaller RMSE. SIGNIFICANCE: The findings of this study support the use of either COM-M or SACR-M using data filtered at 5 and 4 Hz, respectively, to estimate Fv,max during level treadmill runs at endurance speeds.