Biomechanics analysis of seven Tai Chi movements
Nok-Yeung Law, Jing Xian Li
Abstract
This study examined the maximum joint angles and moments, and electromyography (EMG) activity of the lower limbs in an experienced Tai Chi (TC) practitioner in performing four dynamic (Repulse Monkey, Wave-hand in Clouds, Brush Knee Twist Step, and Lateral Forward Step) and three static TC movements (Starting Form, Hero Touch Sky, and Push Hand Back) and compared them with the measures from walking. Integrated EMG (iEMG) and peak EMG of the rectus femoris, adductor longus, tibialis anterior, semitendinosus, erector spinae, gluteus medius, tensor fasciae latae, medial and lateral gastrocnemius muscles were analyzed. One-way analysis of variance showed that compared with walking, TC presented 1) significantly larger hip flexion (71.4° vs. 42.2°) and abduction angles (11.9° vs. 5.3°), smaller knee flexion (45.2° vs. 71.1°) and abduction angles (13.0° vs. 27.7°), larger ankle dorsiflexion (41.4° vs. 11.3°) and abduction angles (8.8° vs. 7.2°); 2) hip flexion moment and knee flexion and abduction moment were significantly larger. Ankle dorsiflexion moment were significantly smaller, whereas ankle abduction moment was significantly larger in two TC movements; and 3) the EMG activity of the muscles in TC varied from 10% to 610% of walking. The knee extensors, hip adductors and abductors had significantly higher peak EMG (430% ± 40%, 240% ± 30%, and 320% ± 90%) and iEMG values (610% ± 30%, 311% ± 30%, and 1.4% ± 20%), respectively. The findings suggested that these TC movements could be a good option for the improvement of muscle strength and range of motion of the lower limbs.