Title: Biomechanics of motor coordination: Modelling and analysis in response to
internal or external perturbation.
The present work had two objectives:
First, an evolution of a biomechanical model that includes the kinematics, BSP,
ground reaction and EMG as input data into a numerical optimization process
(Amarantini and Martin, 2004) was proposed to estimate the moments developed
by the knee flexor and extensor muscle groups under muscle fatigue condition.
The loss of force production capacity due to fatigue was taken into account in the
numerical procedure by means of a frequency analysis of the EMG signal. The
spectral analysis was carried out using wavelet transform. Thirdly, a procedure
was developed to estimate the individual muscle tension with an
optimal prediction of the co-contraction.
Second, an analysis of the muscular coordination was carried out during squat
exercises when faced with either an internal or an external perturbation. The
external perturbation results from supplementary loads added to the subjects
while muscle fatigue of the agonist muscle group qualified the internal
perturbation. Our results show an exploitation of the muscle redundancy both to
stabilize the knee joint and to produce coordinated motions. Moreover, the
exploitation of the muscle redundancy in presence of fatigue differs from that
observed when adding load. Thus, the Central Nervous System exploits
differently, but always in an optimal sense, the muscular redundancy when faced
with a perturbation.
Keywords: Biomechanical modelling, Numericaloptimization, Wavelets transform,
Muscle fatigue, Motor coordination.