Kinetics of the lower limb during two typical Tai Chi movements in the elderly

Tai Chi (TC) is a recommended exercise for elderly people; however, its loading on the joints of the lower limbs is unknown. This study examined the 3D kinetics of the lower limbs during two typical TC movements and walking in the elderly. Fifteen experienced TC practitioners participated. Ground reaction forces, joint moments and time-to-peak joint moment generation were analysed. Compared with walking, both TC movements generated significantly (1) smaller peak ground reaction forces in all directions, except the anterior; (2) larger hip extension, adduction and internal rotational moments, knee adduction/abduction and internal rotation moments and eversion/inversion and external/internal moments of ankle-foot; and (3) longer peak moment generation time for hip extension, adduction and internal rotation, knee extension and ankle dorsiflexion and inversion. The TC loading patterns are consistent with the mechanical behaviour of biological tissues, which could help to strengthen the lower extremities and prevent falls in the elderly.