The Joint Moment Distribution of the Lower Extremity During Tai Chi Gait

Background: As an alternative and complementary practice, Tai Chi is becoming increasingly popular in the United States, especially among the elderly. Although several interventional and qualitative biomechanical studies have been performed, a quantitative approach, such as multi-joints kinetics synergy of ankle, knee and hip, has yet to be performed. To better understand the biomechanics of Tai Chi, the characteristics of the total support moment synergy were studied during Tai Chi gait and compared to normal gait. Methods: Ten healthy, experienced (two years) Tai Chi Chuan practitioners performed normal walking and Tai Chi gait while data was collected using high-speed infrared motion analysis cameras. The joint distributions of the ankle, knee, and hip were calculated by ratio between individual joint moment impulse and total support moment impulse. Using a paired t-test, the joint moment distributions of the lower limb were compared between Tai Chi gait and normal walking. Results: The total support moment of Tai Chi walking was predominated by the contribution of the knee (ankle: 32.78 ± 1.25%; knee: 58.68 ± 1.84%; hip: 8.54 ± 1.91%) whereas the ankle was the primary contributor to support in normal walking (ankle: 67.86 ± 2.76%; knee: 26.18 ± 2.69%; hip: 5.96 ± 1.83%). The contributions of all three joints studied differed significantly (p<0.05) between Tai Chi gait and normal gait. Conclusion: This study demonstrates different kinetics synergy patterns between Tai Chi gait and normal gait. Importantly, Tai Chi gait places a high mechanical demand on the knee joint. Our results provide biomechanical basis of Tai Chi’s benefits on increasing knee joint range of motion and muscle strength, also suggest that prescribing Tai Chi as a potential therapy for people with joint disease, it needs a careful consideration of evaluating mechanical response of people with joint disease during Tai Chi exercise due to higher mechanical demand on the knee joint.