Muscular Fatigue Influences Motor Synergies During Push-ups

This research used the push-up as an experimental paradigm for the study of adaptations in motor synergies throughout the challenge of muscular fatigue. Fatigue was expected to lead to greater synchronization of power production (greater motor synergy) by the Central Nervous System (CNS). Greater between and within-limb synergies would be necessary to overcome the reduced force production of fatigued muscles. Different changes in joint power synergies were expected for eccentric and concentric phases due to muscle properties and direction of gravity. Eleven subjects performed push-ups repetitions to self-selected failure. Subjects initially performed push-ups using positive between and within-limb joint power synergies, however synergies reduced throughout reps. Congruent with hypotheses, between and within-limb synergy reduced at a lesser rate throughout eccentric movements. The strategy used relied on bilateral elbow and shoulder joint production. The CNS was not able to adapt control strategies, but instead the dominant strategy was affected throughout fatigue