Author(s): LI, Y.1, ZHANG, M.1, SUN, Q.1, GAO, X.2, WANG, Z.1, GONG, B.1, WANG, Z.1, CHEN, Y.1, CHEN, J.1, HUO, B.1, Institution: CAPITAL UNIVERSITY OF PHYSICAL EDUCATION AND SPORTS, Country: CHINA, Abstract-ID: 2036

INTRODUCTION:
Exercise-induced fatigue significantly impairs three-point jump shot accuracy by affecting neuromuscular control, including muscle activation patterns and postural balance (1). However, the underlying mechanisms of these impairments remain unclear. Muscle synergies are low-dimensional control modules organized within the central nervous system that coordinate muscle activation to produce efficient movement patterns (2). Synergy analysis offers a valuable approach to understanding how multiple muscles work together to optimize shooting performance (3). This study aimed to compare the muscle synergies of highly trained basketball players during three-point jump shots before and after exercise-induced fatigue to better understand neuromuscular coordination under fatigued conditions.
METHODS:
Fifteen highly trained male basketball players participated in this study. Fatigue was induced through a high-intensity protocol combining shuttle sprints and vertical jumps to simulate game-related conditions (4). During pre- and post-fatigue testing, participants performed three-point jump shots continuously on force plates until three successful and three unsuccessful attempts were recorded, following a standardized warm-up and immediately after fatigue induction. Surface electromyography (EMG) was recorded from 16 muscles across the trunk, upper, and lower extremities during the shooting task. Muscle synergies were identified using non-negative matrix factorization (NNMF) to compare neuromuscular coordination before and after fatigue (5).
RESULTS:
We observed five muscle synergies in successful shots before fatigue, which were reduced to four after fatigue. Unsuccessful shots consistently displayed four synergies both pre- and post-fatigue. Fatigue caused a merging of muscle synergies during the preparation phase, shifting from distinct upper and lower limb activation pre-fatigue to continuous co-activation post-fatigue, closely associated with changes in the center of pressure. During the ball elevation phase, the modular organization of muscle synergies remained unaffected with fatigue. However, significant alterations were observed in the motor modules and primitives of synergy 4 (responsible for push-off), particularly in the tibialis anterior (left: d = -1.06; right: d = -1.47) and gastrocnemius lateral (left: d = 1.61; right: d = 1.66) muscles, resulting in distinct muscle activation patterns and temporal shifts. The time-to-peak of synergy 4 vectors occurred significantly earlier before fatigue than after (d = -0.71).
CONCLUSION:
The changes in the central nervous systems modular control strategies highlight neuromuscular adjustments that are essential for maintaining shooting performance and accuracy under fatigue. Therefore, coaches and athletes should incorporate targeted neuromuscular training programs aimed at optimizing muscle synergy patterns and improving postural control, ensuring athletes can sustain performance even under fatigued conditions.