Abstract
BACKGROUND: Therapeutic climbing (TC) is an emerging physical therapy with demonstrated benefits for musculoskeletal rehabilitation, but its impact on upper-limb muscle activity remains unclear. Existing research predominantly focuses on healthy individuals, leaving muscle recruitment strategies in patients with upper-limb injuries largely unexplored. This study aims to investigate upper-limb muscle activity in patients with unilateral upper-limb injuries and healthy individuals across six TC exercises. METHODS: Eleven patients with right upper-limb fractures and 15 healthy controls were recruited. The electromyographic temporal patterns, activation intensity, bilateral symmetry, and synergy patterns of anterior deltoid (AD), posterior deltoid (PD), biceps brachii (BB), triceps brachii (TB), pronator teres (PT), flexor carpi radialis (FCR), and flexor carpi ulnaris (FCU) were assessed during elbow and knee flexion-extension exercises and four sequential climbing exercises. RESULTS: AD, BB, and PT exhibited greater activation during climbing, while TB was more active in elbow flexion-extension (p < 0.05). Climbing showed lower similarity ([Formula: see text] = 0.72, lag = -3.40%) than flexion-extension (0.80, 1.36%), which was influenced by climbing sequences: starting with the injured side resulted in 0.85 similarity and 1.71% delay, while starting with the uninjured side reduced similarity to 0.6 and increased delay to 7%. Patients exhibited lower activation intensity than controls in AD (p = 0.048), BB (p = 0.017), TB (p = 0.006), and PT (p < 0.01), and greater asymmetry, especially in PT (p < 0.01). Two synergy patterns explained the > 94% variance in both groups. Patients showed altered synergy patterns with increased AD and reduced forearm activation intensity during climbing (p < 0.05). CONCLUSIONS: Patients exhibited delayed muscle activation, decreased activation similarity and intensity, as well as specific compensatory patterns, which were related to both the injury locations and the types of exercises performed. Flexion-extension exercises are more suitable for early rehabilitation. Climbing exercises require greater muscle activation, with climbing starting from the injured side being more suitable for advanced rehabilitation stages. However, injury-induced compensation must be carefully considered in program design.