Climber's muscle excitation and force distribution at different wall angles and body positions

In the domain of rock climbing research, existing biomechanical and physiological studies mostly focus on few, typically upper-body muscles and frequently do not replicate ecological conditions. This study investigates full-body muscle excitation and contact forces between climber and holds in two stationary climbing stances.

Surface electromyography of 22 upper and lower-body muscles and contact forces between climber and holds were recorded in 14 climbers (6 males, 8 females; age 24 ± 6 years; height 1.71 ± 0.07 m; mass 64 ± 8 kg; IRCRA 11-23). We recorded contact forces at three vertices of a rectangle: feet on the lower vertices, right hand on the upper right vertex. The protocol involved five repetitions of two 10-s positions (UP and DOWN) at three wall angles (SLAB: + 5°; VERTICAL: 0°; OVERHANG: -5). Root-mean-square values of electromyographic signals were determined for each repetition and scenario. A two-way RM-ANOVA assessed differences by wall angle and position.

Steeper wall angles cause load transfer from feet to hand, homolateral in UP and contralateral in DOWN. DOWN position involves greater excitation of finger flexors muscles and brachioradialis at all wall angles, suggesting that preference for DOWN position in OVERHANG may not be simply explained by the degree of excitation of those muscles. This study provides a comprehensive mapping of full-body superficial muscle excitation and contact forces across two ecological climbing positions at different wall angles, helping to clarify climbing kinetics, inform targeted training and rehabilitation exercises, and optimize protocols for future research.