The Influence of Motor Learning Combined with Discrete Relaxation Training on Bioelectrical Muscle Activity during Fine-Coordination Manual Skill Execution

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The effectiveness of forming a new fine motor coordination skill, hook-based wire maze tracing, on a hand muscle bioelectrical activity was studied using three training programs: (a) specific maze coordination training, (b) single-session training of discrete relaxation capability in forearm pronators and supinators, and (c) combined practice of maze tracing and discrete relaxation exercises in healthy volunteers (n = 32). According to the training regimens (10 sessions of 30 min per day in the laboratory), four groups were formed: “Coordination” (n = 8), “Relaxation” (n = 8), “Combined” (n = 8), and “Control” (n = 8). Skill acquisition efficiency was assessed by the number of errors and the length of the maze path completed within 3 min. Electromyographic activity of seven muscles (m. pronator teres, supinator, trapezius, biceps brachii, triceps brachii, deltoideus, pectoralis major) during maze tracing was recorded using a wireless Delsys EMG system (Delsys Trigno EMG) integrated with the Vicon motion capture system (Nexus 2.12). It was found that the trained skill improved only in the Coordination and Combined groups, as reflected by a reduction in the number of errors by –62% (p < 0.01) and –55% (p < 0.01), and an increase in the completed maze path length by 53% (p < 0.05) and 69% (p < 0.05), respectively. This confirms the concept of high specificity in complex motor learning. Skill refinement led to two key shifts in muscle activity, also in the Coordination and Combined groups: (1) a significant decrease in the activity of proximal musculature (m.m. trapezius, deltoideus, pectoralis major), which is responsible for shoulder girdle stabilization; (2) a parallel optimization of distal coordination: a reduction in excessive activity of antagonists during pronation (m. biceps brachii) and supination (m. pronator teres), as well as of the agonist during pronation. This reorganization of muscle activity reflects a transition from less efficient control with excessive joint stiffness to differentiated and predictive control, ensuring precision and economy of distal hand movements. The obtained data can be used to improve the training of complex coordination skills in sports and to plan rehabilitative training programs in neurorehabilitation.