Kinematic analysis of overhead squat patterns in sarcopenic and non-sarcopenic older women via markerless 3D RGB-D imaging

Abstract Sarcopenia involves progressive loss of muscle mass and neuromuscular coordination, yet static diagnostic metrics often fail to capture dynamic functional decline. Markerless RGB-D imaging offers a low-cost, clinically practical alternative to conventional motion capture systems. This retrospective cross-sectional study analyzed overhead squat kinematics in 68 older women categorized into sarcopenic ( n = 34) and non-sarcopenic ( n = 34) groups based on AWGS 2019 criteria. A 3D RGB-D system quantified squat depth, squat speed, total 3D head path length, head sway, inter-knee distance, and knee flexion angle during a five-repetition task. The sarcopenic group exhibited significantly reduced squat depth ( p < 0.001), squat speed ( p < 0.001), total 3D head path length ( p = 0.010), inter-knee distance ( p = 0.013), and knee flexion angle ( p = 0.004), and increased anteroposterior head sway ( p = 0.027). All six significant differences were maintained after Benjamini-Hochberg false discovery rate correction and after ANCOVA adjustment for body weight, with effect sizes ranging from medium ( d = 0.547) to large ( d = 1.007). These findings indicate that markerless 3D RGB-D imaging can quantify overhead squat kinematic differences between sarcopenic and non-sarcopenic older women. Further studies must establish measurement validity, responsiveness, and longitudinal or rehabilitation utility.