Effect of occlusion on range of motion of spinal alignment during trunk flexion varies depending on exercise habits

Author(s): Mutsumi Takahashi, Yogetsu Bando, Takuya Fukui

The purpose of this study was to clarify the differences in the effects of occlusion on the range of motion of spinal alignment during trunk flexion based on the participants’ exercise habits. Participants were 16 healthy men, 14 trampoline gymnasts and 15 rugby players. Using a spinal shape analyzer, the lumbar range of motion, hip joint range of motion (HJM), and spinal range of motion (SM) during trunk flexion were measured. Differences in the range of motion of spinal alignment due to participant group and occlusion condition were analyzed using two-way ANOVA. In addition, the difference in the reduction rate in range of motion for each alignment due to clenching was analyzed using the Friedman test. Differences in the range of motion of spinal alignment among participants were noted in all measurement items, with the trampoline gymnasts showing the highest values regardless of occlusion conditions. Differences due to occlusal conditions were observed at all levels except for the SM in healthy men, and the range of motion of spinal alignment was greater when the mandibular rest position than when the clenching. The reduction rate in HJM due to clenching in rugby players was significantly greater than that of SM. The results of this study showed that the effect of occlusion on spinal alignment range of motion during trunk flexion exercise was greater in participants with exercise habits, and trunk stabilization was more pronounced. Furthermore, it became clear that rugby players tend to rely on hip joint movement during trunk flexion.