Biomechanical Characteristics of Dynamic Balance in Tai-Chi Gait with Comparison to Normal Gait

Abstract

PURPOSE: As Tai-Chi gait has been assumed as one of the proper exercises as to improve stability of the movement, muscle endurance and flexibility of the body according to many health promotion surveys, little evidence was obtained from scientific points of view. As far as the stability of the movement, i.e., dynamic balance, biomechanical research has been focused on respective locations of center of mass (CoM) and center of pressure (CoP) and the resultant moment around CoM. The purpose of this study was to determine the characteristics of biomechanical dynamic stability balance in Tai-Chi gait with comparison to that in normal gait. METHODS: Twelve healthy adults with Tai-Chi expert participated in this study. 3D kinematic and kinetic data during Tai-Chi gait (KANKA 24) and normal gait movements were respectively recorded by using 12 optic motion capture cameras (VICON512, Motion System Corp) and 8 force platforms (EFP-386A, Kyowa Electric Inst, Japan) installed under the 7.2 m walkway in laboratory studio. Distance between CoM and CoP and resultant moments around CoM in each movement planes (frontal, sagittal and transverse) were calculated using kinematic and kinetic data recorded from Tai-Chi and normal gaits. RESULTS: Anterior/posterior distance (cm/body height) between CoM and CoP was significantly lower in Tai-Chi gait (3.2 ± 1.9) compared to that of normal gait (12.8 ± 3.7). Higher moments around CoM (Nm/kg body weight) were observed in sagittal plane, but Tai-Chi gait (2.17 ± 0.61) exhibited one forth compared to the value of normal gait (8.94 ± 1.40). CONCLUSIONS: Tai-chi gait is characterized as to move the CoM on the CoP, resulting smaller resultant moments around CoM especially in anterior/posterior plane. Those findings suggest that Tai-Chi gait is more stable in dynamic balance compared to normal gait, which might be useful training for preventing risk of fall down during normal gait.