Kinetics and Kinematics of the Lower Extremity During Performance of Two Typical Tai Chi Movements by the Elders

Tai Chi Chuan is a safe alternative for those who wish to improve balance and physical wellbeing. It is a popular form of exercise that is supported by a growing body of research aimed towards improving the health of a sedentary elderly population. The purpose of this study was to examine the biomechanical features of the lower extremity during performance of two Tai Chi movements, the “Repulse Monkey (RM)” and “Wave-hands in clouds (WHIC).” The study’s parameters included quantitative measures of the temporospatial, kinematic, and kinetic characteristics of the lower extremities. A group of experienced male Tai Chi practitioners (n = 15) between the ages of 65 to 75, performed “Repulse Monkey (RM)”, “Wave-hand in Cloud (WHIC)”, and forward walking. Three-dimensional (3-D) kinematic and kinetic data was collected using VICON motion analysis system with 10 infrared cameras and 4 force plates. The following variables were examined: stride width, step length, step width, single- and double-support times, centre of mass (COM) displacement, peak joint angles, range of motion, peak joint moments, time to peak moment, and ground reaction force (GRF). The differences in the measurements of the two Tai Chi movements were compared with walking using two-way ANOVA. The study’s results showed that the two Tai Chi movements elicit gentle and fluid changes to position of the upper body mass and the joints in the lower extremity. In terms of joint kinematics, the knee remained flexed throughout RM and WHIC. Unlike walking, RM had larger abduction and adduction angles at the knee joints and large plantar- and dorsiflexion ROM at the ankle. Reduced posterior, mediolateral, and vertical GRF were seen; the loading joints at the ankle and hip were gentle and smaller than walking. Varus/valgus moments were notably larger at the knee joint during RM and eversion moment was larger at the ankle joint during WHIC movement. A large, but slow loading rate at the knee joint has implication towards the viscoelastic properties of the knee. A better understanding of RM and WHIC would facilitate the improvement of balance, physical capacity, and joint flexibility for the elders