Author(s): BONELLI, E., COLOMBO, A., RAMPICHINI, S., LIMONTA, E., Institution: POLITECNICO DI MILANO, Country: ITALY, Abstract-ID: 1283

INTRODUCTION:
Sport climbing is transitioning from a niche to a mainstream activity. Understanding of this sport’s biomechanics is still fragmentary. We have developed sensors to measure the 3D contact force vectors between a climber and the climbing holds (1). Such an apparatus has been employed to characterize the kinetics of 2 typical positions at 3 different wall angle. In this preliminary data analysis we report the force distribution on 3 climbing holds.
METHODS:
We recruited 16 climbers (8m, 8f, age 26±7yr, height 1.71±0.06m, body mass 66±9kg, right handed, climbing level >18 in IRCRA scale). One position was characterized by fully extended legs and flexed dominant arm (A), the other by bent legs and fully extended dominant arm (B). Climbers had feet on 2 holds 0.46m apart and right hand on a hold 1.44m or 1.62m above the footholds, depending on subject height. The 3 holds were identical 0.06m deep crimps. After familiarization, climbers alternated 10x10s repetitions of A and B, with 30s recovery time. This sequence was repeated at 3 wall angles: +5, 0, -5 degrees from vertical. The magnitudes of hand (FHand), right (FRfoot) and left (FLfoot) foot forces during A or B were normalized by body mass. The 2 positions and the 3 wall angles compose 6 scenarios: A+5/0/-5 and B+5/0/-5. For each triplet (scenario, subject, hold), we tested reliability (ICC>0.5) of the 10 measures. Unreliable triplets were excluded, the 10 measures of reliable triplets were averaged, then outlying triplets were removed (Matlab function robustcov). Average values for each triplet were then considered. We performed a Shapiro-Wilk test to check the distributions normality and a two-way RM-ANOVA (factor: position; level: wall angle; α=0.01) to assess differences among scenarios.
RESULTS:
Forces in the 6 scenarios are normally distributed, except for a slightly non-normal distribution for FHand in A0. FLfoot is independent of wall angle, and larger in A than in B (A-5: 0.55±0.04, A0: 0.55±0.04, A+5: 0.52±0.06, B-5: 0.34±0.03, B0: 0.34±0.03, B+5: 0.33±0.04). The difference FRfoot - FHand instead highlights a significant (P<0.001) load transfer as the wall angle transitions from -5 to +5 degrees in both positions (A-5: 0.43±0.03, A0: 0.29±0.04, A+5: 0.15±0.06, B-5: 0.02±0.09, B0: -0.05±0.09, B+5: -0.12±0.08). FLfoot appears higher than FRfoot in all scenarios (A-5: 0.12±0.07, A0: 0.16±0.08, A+5: 0.16±0.08, B-5: -0.01±0.06, B0: 0.01±0.06, B+5: 0.03±0.05).
CONCLUSION:
In both positions, body kinematic adaptation to changing wall angle is predominantly homolateral, between the hand and the same-side foot. The load on the other foot is unaffected by wall angle. Load distribution is predominantly contralateral, as FLfoot is larger than FRfoot in all but one scenarios. These findings provide valuable bases to characterize climbing strategies and optimize training.

REFERENCES:
 (1) Colombo et al, Frontiers in Sports and Active Living, 2023