Development and Measurement Properties of a Custom-Built Punch Force Dynamometer Based on S-Type Load Cells

Accurate quantification of punch force is essential for performance assessment and training optimization in combat sports. This study introduces a Custom-Built Punch Force Dynamometer using two S-type load cells and evaluates its reliability, sensitivity, and partial ecological validity under sport-specific conditions. The device was mounted vertically on a wall and tested under both controlled and sport-specific conditions. Mechanical trials were assessed using a standardized drop-weight protocol with repeated trials. Partial ecological validity involved 11 experienced athletes from striking-based combat sports performing standardized straight punches across two lab visits. Reliability metrics included intraclass correlation coefficients (ICC), standard error of measurement (SEM), and smallest worthwhile change (SWC). The dynamometer demonstrated excellent reliability during mechanical trials (ICC > 0.90) and good to excellent reliability during partial ecological validity (ICC = 0.75-0.90). SEM values were consistently lower than SWC, indicating strong measurement sensitivity. These findings support the reliability and practical utility of this device for assessing punch force in both laboratory-based research and sport-specific applications.