Biomechanics analysis of seven Tai Chi movements

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.

Keywords: EMG; Joint angles; Joint moments; Tai Chi; Walking.

Fig. 1

Illustration of the ratio of integrated electromyography and maximum electromyography (EMG) values of each Tai Chi movement to walking values of each muscle. BKTS: Brush Knee & Twist Step, EMG: electromyography, iEMG: integrated EMG, LFS: Lateral Forward Step, RM: Repulse Monkey, TC: Tai Chi, WHIC: Wave-hand in Cloud. The left bottom chart of medial gastrocnemius doesn’t include the EMG data values from two static Tai Chi movements because the EMG signal were missing due to problems with the EMG sensors’ batteries. ∗ p ​≤ ​0.001, vs. walking; ˆ p ≤ ​0.05, vs. walking.

Fig. 2

Angular displacement of the hip, knee, & ankle in sagittal (left column) and frontal plane (right column) during one gait cycle of walking (solid line) and four Tai Chi movements, lateral forward step (wide dash), repulse monkey (narrow dash line), wave-hand in cloud (dash-dot line) and brush knee & twist step (dotted line).

Fig. 3

Joint moment patterns of in sagittal plane (left column) and frontal plane (right column) during one gait cycle of walking (solid line) and four Tai Chi movements, Lateral Forward Step (wide dash), Repulse Monkey (narrow dash line), Wave-hand in Cloud (dash-dot line) and Brush Knee & Twist Step (dotted line).

Fig. 4

Electromyography activity of the gluteus medius (left column) and tensor fasciae latae (right column) during performing Brush Knee & Twist Step (top), Repulse Monkey (middle), and Lateral Forward Step (bottom). BKTS: Brush Knee & Twist Step, EMG: electromyography, LFS: Lateral Forward Step, RM: Repulse Monkey.