Effects of Slouched and Erect Sitting Postures on Upper Limb Kinematics During Tasks Associated with Musculoskeletal Disorder Risk

OCCUPATIONAL APPLICATIONSTo manage upper limb musculoskeletal disorders, treatments based on reducing spinal curvatures are used empirically. Spinal posture has been shown to modify upper limb functional capacities in terms of maximum voluntary forces and fatigability. The aim of the study was to determine whether spinal curvatures also influenced upper limb joint angles during tasks associated with a risk of musculoskeletal disorders. Twenty-two healthy participants were placed in a slouched or erect sitting posture, in random order. Three standardized tasks were performed three times each in both postures. In the erect posture, shoulder flexion was consistently decreased, and shoulder abduction was decreased over most or all of the tasks analyzed. Elbow extension was increased over half of the duration of a single task. Thus, slouched or erect seated spinal posture influences proximal upper limb joint angles. Ergonomists should consider spinal posture even when focusing on proximal upper limb musculoskeletal disorders.