Influence of Foot Stance on Lower Body Sway during Bipedal Standing

Abstract

[Purpose] This study examined and compared lower leg and pelvis sway in standing with a narrow stance and a wide stance. [Subjects] The subjects were 9 young healthy adults. [Methods] Each subject wore three accelero-gyro sensors on the lower part of both legs and on the pelvis. The subjects performed two 40-second balance tasks in the wide stance and the Romberg stance with their eyes open. Angular velocities of the three axes were measured to calculate the Euler angles (θ, ϕ, and ψ). The maximum angle of inclination (maximum polar angle) and azimuth were calculated from θ and ϕ, respectively. [Results] The maximum polar angles of the wide stance and Romberg stance were not significantly different. When the maximum polar angles measured by the sensors at the three locations were compared, the values of the wide stance were significantly different, while those of the Romberg stance were not significantly different. [Conclusion] Our findings suggest that the lower leg and pelvis sway are synchronous in healthy men during standing with a narrow stance. Also, the pelvis tended to sway in the mediolateral directions.