Skill Differentiation in Wrestling: Relationship Between Muscle Complexity and Local Dynamic Stability in Neuromuscular Control

Complexity and local dynamic stability (LDS) of electromyographic (EMG) signals are valuable indicators for understanding motor control mechanisms and distinguishing skill levels in dynamic sports such as wrestling. This study investigates the relationship between complexity and LDS of EMG signals to understand the neuromuscular mechanisms underlying skill differentiation in wrestling. The complexity [using the Higuchi fractal dimension (FD)] and LDS [using the largest Lyapunov exponent (LLE)] activity of the upper limb muscles were calculated in elite and sub-elite wrestlers (N = 72) during the arm-drag and double-leg attack techniques. The correlation between complexity and LDS was evaluated using Pearson's correlation coefficient, and random forest analysis was used to determine their importance in differentiating skill levels. Elite wrestlers showed higher complexity, LDS, and correlation between complexity and LDS in EMG signals than sub-elite wrestlers. Random forest analysis showed that complexity is more important than LDS in differentiating skill levels. The findings show that training programs should be designed according to athletes' skill levels. Training programs should adopt a phased approach, initially targeting LDS and motor control and integrating complex exercises to promote adaptability and variability in motor responses. This approach can help athletes improve their motor control and achieve higher skill levels.