Upper‐Body Neuromechanical Coordination Strategies During Fatiguing Sustained Dead Hangs in Climbers

ABSTRACT This study investigated how upper‐body joint and muscle coordination strategies are related and adapted under fatigue during sustained dead hangs, a task relevant to climbing performance. Eleven climbers performed a dead hang until failure. Joint coordination variability ( r CV) was assessed using a modified vector coding method in kinematic data. Muscle coordination was analyzed through EMG linear and non‐linear dependencies between signals with coherence (β/γCOH) and mutual information (β/γMI) at beta and gamma bands. Fatigue induced joint‐specific changes in coordination variability, with wrist r CV decreasing from START to END (39.6 ± 32.9% vs. 21.2 ± 12.4%; p = 0.002), showing a redistribution of coordination demands across the upper limb. At the muscle level, βCOH increased in selected postural muscle pairs, including brachioradialis–biceps ( p = 0.04), trapezius–biceps ( p = 0.04), and trapezius–brachioradialis ( p = 0.003), while γCOH decreased for trapezius–brachioradialis ( p = 0.01). In addition, βMI increased for brachioradialis ( p = 0.01) and brachioradialis–biceps ( p = 0.01), while γMI increased within the finger flexors ( p = 0.03). Repeated‐measures correlation revealed inverse within‐subject associations between wrist r CV and trapezius–brachioradialis γCOH (r rm (10) = −0.57, p = 0.05) and finger‐flexor γMI (r rm (10) = −0.61, p = 0.03). These findings are consistent with a multi‐level compensatory strategy in which distal joint behavior becomes more constrained while proximal and local muscle coordination is reinforced to sustain suspension under fatigue, offering new insight into joint–muscle coordination during climbing‐specific isometric tasks.