Sport Sciences Research Institute Motor Behavior 2538-273X 15 51 2023 03 21 Effect of central and peripheral muscle fatigue contribution after ankle submaximal fatiguing contractions on muscle synergies and postural control Effect of central and peripheral muscle fatigue contribution after ankle submaximal fatiguing contractions on muscle synergies and postural control 67 90 2542 10.22089/mbj.2021.10287.1959 FA Zeinab Hatami Bahmanbegloo Sport and physical education, Shahid beheshti university, Tehran Alireza Farsi Sport and physical education, Shahid beheshti university, Tehran 0000-0002-2086-6632 Hamidollah Hassanlouie Sport and physical education, Shahid beheshti university, Tehran Markus Tilp Institute of Movement Science, Sport and Health, University of Graz, Mozartgasse 14, A- 8010 Graz, Austria Journal Article 2021 03 29 Although the effect of ankle muscles on postural control and muscle synergies has well been investigated, it is needed to study more about the contribution of central and peripheral fatigue of submaximal contractions on postural control and muscle synergies. The aim of this study was to investigate the effect of submaximal fatiguing exercise that induce preferentially central fatigue on muscle synergy and postural control. For this purpose, 12 volunteer subjects participated in this study. The tibia nerve was electrically stimulated to assess the M-wave, central fatigue (voluntary activation) and peripheral fatigue (rest imposed twitch) during voluntary maximal contractions on dynamometer. Moreover, electromyography activity of ten muscles and COP were recorded to assess muscle synergy and postural stability respectively during anterior-posterior voluntary sway on force plate. In order to induce fatiguing exercise the subjects performed submaximal fatiguing contractions on dynamometer and all of the mentioned variables again were measured. The effect of the fatiguing protocol tested with paired-samples T Test and Z Fisher Test. Submaximal contractions induced greater increases of COP sway area. Muscles activation, muscle synergies variance decreased and the number of co-contractions increased significantly after submaximal contractions (P = 0.01). Contribution of central fatigue (16.64%) significantly greater than peripheral fatigue (2.32%) after submaximal contractions (P = 0.02). The results of this study showed that more central fatigue after submaximal contraction leads to more COP changes. Therefore, investigating central and peripheral mechanisms following ankle fatiguing contractions may be useful for scheduling rehabilitation and balance training programs. Although the effect of ankle muscles on postural control and muscle synergies has well been investigated, it is needed to study more about the contribution of central and peripheral fatigue of submaximal contractions on postural control and muscle synergies. The aim of this study was to investigate the effect of submaximal fatiguing exercise that induce preferentially central fatigue on muscle synergy and postural control. For this purpose, 12 volunteer subjects participated in this study. The tibia nerve was electrically stimulated to assess the M-wave, central fatigue (voluntary activation) and peripheral fatigue (rest imposed twitch) during voluntary maximal contractions on dynamometer. Moreover, electromyography activity of ten muscles and COP were recorded to assess muscle synergy and postural stability respectively during anterior-posterior voluntary sway on force plate. In order to induce fatiguing exercise the subjects performed submaximal fatiguing contractions on dynamometer and all of the mentioned variables again were measured. The effect of the fatiguing protocol tested with paired-samples T Test and Z Fisher Test. Submaximal contractions induced greater increases of COP sway area. Muscles activation, muscle synergies variance decreased and the number of co-contractions increased significantly after submaximal contractions (P = 0.01). Contribution of central fatigue (16.64%) significantly greater than peripheral fatigue (2.32%) after submaximal contractions (P = 0.02). The results of this study showed that more central fatigue after submaximal contraction leads to more COP changes. Therefore, investigating central and peripheral mechanisms following ankle fatiguing contractions may be useful for scheduling rehabilitation and balance training programs. https://mbj.ssrc.ac.ir/article_2542_c3a690be93aa602ee2dc0ccab5b7b67e.pdf