A H Dewolf1,2, Y P Ivanenko3, R M Mesquita1, F Lacquaniti2,3, P A Willems4. 1. Laboratory of Biomechanics and Physiology of Locomotion, Institute of Neuroscience, Université Catholique de Louvain (UCL-FSM), Place P. de Coubertin, 1, 1348, Louvain-la-Neuve, Belgium. 2. Department of Systems Medicine and Center of Space Biomedicine, University of Rome Tor Vergata, 00133, Rome, Italy. 3. Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, 00179, Rome, Italy. 4. Laboratory of Biomechanics and Physiology of Locomotion, Institute of Neuroscience, Université Catholique de Louvain (UCL-FSM), Place P. de Coubertin, 1, 1348, Louvain-la-Neuve, Belgium. patrick.willems@uclouvain.be.
Abstract
PURPOSE: Walking against a constant horizontal traction force which either hinders or aids the motion of the centre of mass of the body (COM) will create a discrepancy between the positive and negative work being done by the muscles and may thus affect the mechanics and energetics of walking. We aimed at investigating how this imbalance affects the exchange between potential and kinetic energy of the COM and how its dynamics is related to specific spatiotemporal organisation of motor pool activity in the spinal cord. To understand if and how the spinal cord activation may be associated with COM dynamics, we also compared the neuromechanical adjustments brought on by a horizontal force with published data about those brought on by a slope. METHODS: Ten subjects walked on a treadmill at different speeds with different traction forces. We recorded kinetics, kinematics, and electromyographic activity of 16 lower-limb muscles and assessed the spinal locomotor output by mapping them onto the rostrocaudal location of the motoneuron pools. RESULTS: When walking with a hindering force, the major part of the exchange between potential and kinetic energy of the COM occurs during the first part of stance, whereas with an aiding force exchanges increase during the second part of stance. Those changes occur since limb and trunk orientations remain aligned with the average orientation of the ground reaction force vector. Our results also show the sacral motor pools decreased their activity with an aiding force and increased with a hindering one, whereas the lumbar motor pools increased their engagement both with an aiding and a hindering force. CONCLUSION: Our findings suggest that applying a constant horizontal force results in similar modifications of COM dynamics and spinal motor output to those observed when walking on slopes, consistent with common principles of motor pool functioning and biomechanics of locomotion.
PURPOSE: Walking against a constant horizontal traction force which either hinders or aids the motion of the centre of mass of the body (COM) will create a discrepancy between the positive and negative work being done by the muscles and may thus affect the mechanics and energetics of walking. We aimed at investigating how this imbalance affects the exchange between potential and kinetic energy of the COM and how its dynamics is related to specific spatiotemporal organisation of motor pool activity in the spinal cord. To understand if and how the spinal cord activation may be associated with COM dynamics, we also compared the neuromechanical adjustments brought on by a horizontal force with published data about those brought on by a slope. METHODS: Ten subjects walked on a treadmill at different speeds with different traction forces. We recorded kinetics, kinematics, and electromyographic activity of 16 lower-limb muscles and assessed the spinal locomotor output by mapping them onto the rostrocaudal location of the motoneuron pools. RESULTS: When walking with a hindering force, the major part of the exchange between potential and kinetic energy of the COM occurs during the first part of stance, whereas with an aiding force exchanges increase during the second part of stance. Those changes occur since limb and trunk orientations remain aligned with the average orientation of the ground reaction force vector. Our results also show the sacral motor pools decreased their activity with an aiding force and increased with a hindering one, whereas the lumbar motor pools increased their engagement both with an aiding and a hindering force. CONCLUSION: Our findings suggest that applying a constant horizontal force results in similar modifications of COM dynamics and spinal motor output to those observed when walking on slopes, consistent with common principles of motor pool functioning and biomechanics of locomotion.
Keywords:
Braking and propulsion force; COM dynamics; Neuromechanics; Pendular energy exchange; Spinal maps
Authors: Surabhi N Simha; Jeremy D Wong; Jessica C Selinger; J Maxwell Donelan Journal: IEEE Trans Neural Syst Rehabil Eng Date: 2019-05-17 Impact factor: 3.802
Authors: Yuri P Ivanenko; Nadia Dominici; Germana Cappellini; Ambrogio Di Paolo; Carlo Giannini; Richard E Poppele; Francesco Lacquaniti Journal: J Neurosci Date: 2013-02-13 Impact factor: 6.167
Authors: Arthur H Dewolf; Francesca Sylos-Labini; Germana Cappellini; Yury Ivanenko; Francesco Lacquaniti Journal: PLoS One Date: 2021-02-17 Impact factor: 3.240