Musculoskeletal and Ergonomic Demands of the Pumping Maneuver in Laser-Class Sailing: An Integrated Biomechanical Analysis

Background: This study investigates the biomechanical and physiological demands of the pumping maneuver in Laser-class sailing, a dynamic technique requiring coordinated upper and lower body oscillations to generate propulsion in marginal wind conditions. The proposed framework utilizes a mixed-methods approach combining musculoskeletal simulation, kinematic analysis, ergonomic assessment, and subjective evaluation. Methods: Thirty-six experienced Laser sailors completed a questionnaire quantifying perceived discomfort using the Borg CR-10 scale across three temporal phases: during pumping, immediately post-sailing, and the following day. The pumping motion was replicated on land by an experienced sailor and analyzed using marker-based motion capture and Delmia® musculoskeletal simulation software. REBA ergonomic assessment was performed to evaluate postural risk. Results: Musculoskeletal simulation revealed maximal normalized activation (100.0%) in seven deep trunk stabilizers and left latissimus dorsi. Pronounced lateral asymmetry was observed, with right-sided trunk dominance. Lower extremity activation was moderate on the right and minimal on the left. Kinematic analysis identified substantial lumbar excursions (45.3° flexion-extension, 38.7° lateral flexion, 42.1° axial rotation). REBA assessment yielded a score of 11 (Very High Risk). Questionnaire data revealed a paradoxical relationship between objective activation and subjective fatigue: maximal trunk activation corresponded to lower perceived fatigue, while moderate lower limb activation corresponded to higher perceived fatigue. Musculoskeletal discomfort prevalence was 72.2%, concentrated in the lower back, shoulders, and knees. Conclusions: Findings highlight the deep trunk stabilizers, latissimus dorsi, and lower extremities as primary contributors to pumping execution, while emphasizing pronounced lateral asymmetry and high ergonomic risk. The activation-fatigue paradox suggests differential physiological mechanisms between trunk stabilizers and lower limb muscles. These insights can guide training interventions, injury prevention strategies, and ergonomic modifications to optimize performance and reduce injury risk in competitive sailing.