Unexperienced mechanical effects of muscular fatigue can be predicted by the Central Nervous System as revealed by anticipatory postural adjustments

• Published in: Experimental brain research Vol. 232; no. 9; pp. 2931 - 2943
• Main Authors: Monjo, Florian, Forestier, Nicolas
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.09.2014; Springer; Springer Nature B.V; Springer Verlag
• Subjects: Adaptation, Physiological - physiology; Algorithms; Analysis; Arm - physiology; Biological and medical sciences; Biomechanical Phenomena; Biomechanics; Biomedical and Life Sciences; Biomedicine; brain; Central nervous system; Cognitive science; Electromyography; Fatigue; Female; Fundamental and applied biological sciences. Psychology; Humans; Isometric Contraction; Kinematics; Male; Mechanical properties; Movement - physiology; Muscle fatigue; Muscle Fatigue - physiology; Muscle, Skeletal - physiology; Muscles; Nervous system; Neurology; Neuroscience; Neurosciences; Postural Balance - physiology; Posture; prediction; Predictive Value of Tests; Research Article; Statistics, Nonparametric; Vertebrates: nervous system and sense organs; Young Adult; First trial; Internal models; Anticipatory postural adjustments; Muscular fatigue; Central nervous system; Fatigue; Models; Postural fitting
• ISSN: 0014-4819; 1432-1106; 1432-1106
• DOI: 10.1007/s00221-014-3975-0

Muscular fatigue effects have been shown to be compensated by the implementation of adaptive compensatory neuromuscular strategies, resulting in modifications of the initial motion coordination. However, no studies have focused on the efficiency of the feedforward motor commands when muscular fatigue occurs for the first time during a particular movement. This study included 18 healthy subjects who had to perform arm-raising movements in a standing posture at a maximal velocity before and after a fatiguing procedure involving focal muscles. The arm-raising task implies the generation of predictive processes of control, namely Anticipatory Postural Adjustments (APAs), whose temporal and quantitative features have been shown to be dependent on the kinematics of the upcoming arm-raising movement. By altering significantly the kinematic profile of the focal movement with a fatiguing procedure, we sought to find out whether APAs scaled to the lower mechanical disturbance. APAs were measured using surface electromyography. Following the fatiguing procedure, acceleration peaks of the arm movement decreased by ~27 %. APAs scaled to this lower fatigue-related disturbance during the very first trial post-fatigue, suggesting that the Central Nervous System can predict unexperienced mechanical effects of muscle fatigue. It is suggested that these results are accounted for by prediction processes in which the central integration of the groups III and IV afferents leads to an update of the internal model by remapping the relationship between focal motor command magnitude and the actual mechanical output.