Estimating Lumbar Spinal Loads during a Golf Swing Using an Emg-assisted Optimization Model Approach

INTRODUCTION: A number of surveys have shown that the golf swing is increasingly being recognized as a potential cause of lower back injuries. Although many researchers have been interested in seeking a “perfect” golf swing to improve performance, surprisingly, few studies have investigated the potential causes of injury such as back pain. The forces generated by the musculature surrounding the lumbar spine often contribute a large part of spinal stresses. Tissue damage occurs when the force to which it is exposed to at a particular instant exceeds the tissue’s tolerance. Therefore, large mechanical stresses on the lumbar spine are widely believed to be related to the development of low-back pain. During a golf swing, the L4-L5 disc as well as the lumbosacral (L5-S1) disc are subjected to large magnitudes of compressive loads in addition to the continuous static load due to the weight of the trunk. In order to explore the relationship between lumbar spinal loads and lower back injury, it is important to have knowledge of the lumbar spinal loads during a golf swing. The purpose of this study was to estimate the loads acting on the spinal motion segment at the L4-L5 level (lower back) during a golf swing using an electromyography (EMG)-assisted optimization model (Cholewicki & McGill, 1994). It was expected that a golf swing would introduce large compressive, antero-posterior (A/P) shear, and medio-lateral (M/L) shear loads acting on the L4-L5 disc.