Assessing Shoulder Joint Kinematics During the Bench Press Exercise in Competitive Powerlifters With Markerless Motion Capture.
Motlagh JG, Lipps DB. · Journal of strength and conditioning research · 2026
Abstract Motlagh, JG and Lipps, DB. Assessing shoulder joint kinematics during the bench press exercise in competitive powerlifters with markerless motion capture. J Strength Cond Res XX(X): 000-000, 2026-The barbell bench press is fundamental in strength training and powerlifting, yet shoulder injury risk related to this exercise, especially among female athletes, is understudied. Markerless motion capture provides a scalable approach for examining three-dimensional joint kinematics during athletic maneuvers. This study characterized changes in glenohumeral range of motion throughout a standardized, fatiguing bench press protocol and assessed differences by biological sex. Nineteen competitive powerlifters (10 male and 9 female subjects) completed 3 sets of 8 repetitions of barbell bench press at 73.9% of self-reported 1-repetition maximum, following a standardized warm-up. Shoulder kinematics were recorded with markerless motion capture and analyzed with Theia3D. Primary outcomes included the intra- and interset 3D range of motion of the glenohumeral joint. Repeated-measures ANOVA examined the effects of repetition, set, arm dominance, and sex. Within each set, significant intraset increases in range of motion were observed between the first and second-to-last repetition across all joint axes: plane of elevation (p = 0.002), elevation (p < 0.001), and rotation (p < 0.001). No significant interset changes were found. Female lifters demonstrated significantly greater increases in glenohumeral range of motion compared with male powerlifters in the plane of elevation (p = 0.011) and elevation (p = 0.036) axes but not in rotation. This study found notable intraset increases in glenohumeral range of motion during repeated bench press, with these increases most pronounced in female lifters. The
Findings: underscore the importance of targeted injury prevention strategies and support the value of markerless motion capture for sport-specific biomechanical assessment.