The Impact of a Dynamic Trunk Axial Twisting Task to Fatigue on Musculoskeletal Responses

The purpose of this thesis was to examine pain developers (PD) and non-pain developers (NPD) musculoskeletal responses to a repetitive dynamic axial twisting exposure when performed to self-reported fatigue. Trunk/pelvis muscle activation & kinematics, self-reported transient pain, range of motion (ROM) tests, and a repetitive dynamic axial twisting exposure were collected on 13 female softball players. Seven participants developed transient pain. The PD had a decrease in mean muscle activation and spine segment angles in the ROM tasks and the axial twisting exposure. Yet, the PD reached the same maximum spine segment angle as the NPD during the exposure with lower muscle activation. This suggests that PD were using a different strategy to perform the exposure, one that could be the source of transient pain. More research needs to be conducted to better understand musculoskeletal responses to twisting, especially in PD, to identify the possible mechanisms that lead to LBP/injury.