Background: The batting motion has been reported to have a possible association with the development of low back pain (LBP) in baseball players. This study aimed to identify the kinematics of the batting motion in baseball players with a history of LBP, focusing on rotational and extension movements of the pelvis and trunk.
Methods: This study employed a cross-sectional design. Twenty-five experienced baseball players (age: 20.8±1.6 years; height: 173.4±6.3 cm; weight: 68.4±9.4 kg) were randomly recruited at the International University of Health and Welfare university, and all participants were classified into either the LBP (N.=13) or non-LBP (N.=12) group. The joint angles of the trunk and pelvis were measured during batting motion with a three-dimensional motion analysis system.
Results: The LBP group showed a significantly smaller trunk rotation and pelvis posterior tilt angle and earlier timing of trunk rotation to the batting side as compared to the non-LBP group (P<0.05).
Conclusions: This study revealed that experienced players with no history of LBP showed a delay in the timing of trunk rotation to the batting side while increasing the trunk rotation angle to the non-batting side to efficiently transfer the rotational energy generated from the lower limbs to the trunk and the upper limbs. Conversely, players with a history of LBP might have repeated inefficient motion in the process of transferring rotational energy generated by the lower extremities, pelvis, and trunk to the upper extremities.