Anticipatory postural adjustment and T'ai Chi Ch'uan.

Recently much attention has focused on T'ai Chi Ch'uan as a method of improving balance and reducing the risk of falls in the elderly. Little has been done to determine the mechanism of these improvements. This study examined the effects of a sixteen week training program on anticipatory postural adjustments (APA). Eight subjects (median age 36.5) in good health, with no prior training in T'ai Chi were tested. The battery of tests included load dropping of 2.2 kg loads by the subjects standing on an unstable board placed on a force platform. The level and direction of instability were varied. The results show counterintuitive reductions in the APAs of several muscle groups while the stability of standing improved. We interpret the findings as an indication that practicing T'ai Chi leads to a greater use of the elasticity of the peripheral structures involving muscles, ligaments, and tendons while the participation of the central neutral structures in postural equilibrium is decreased.