PURPOSE: Sand walking, a type of marine healing program, has been adopted as a sports training and rehabilitation method because it lowers the risk for injury by reducing muscle and joint loads through shock relief. This study performed a three-dimensional (3D) biomechanical analysis to compare walking on firm versus sandy surfaces in healthy adults in a laboratory environment that closely replicated real beach sand.METHODS: The 3D joint range of motion (ROM), stance time and muscle activity of the lower extremities were analyzed while 34 healthy adults walked on firm versus sandy surfaces using a constructed sand track (7.2×0.9×0.2 cm).RESULTS: Sagittal ROMs of the hip and knee joints were significantly greater on the sandy surface than those on the firm surface, whereas the horizontal ROM of the knee joint was significantly lower on the sandy surface than that on the firm surface. Ankle ROMs were significantly greater across all planes. Significantly longer stance times were observed for the sandy surface versus the firm surface. The gastrocnemius and gluteus medius muscles exhibited significantly higher activity on the sandy surface versus the firm surface during the loading and terminal stance phases.CONCLUSIONS: This study revealed 3D biomechanical changes in the lower extremities during sand walking, increasing joint ROM and muscle activity while extending stance time, suggesting that beach sand is a suitable resource for gait rehabilitation and marine healing programs.
Son et al. (Sat,) studied this question.