UVM Theses and Dissertations
Purpose and Background This study was to quantitatively characterize the biomechanics of a selected Tai Chi gait in young and elderly subjects. Studies have shown Tai Chi to be an effective exercise for strength, flexibility and balance, particularly in elderly people. An understanding of the biomechanical characteristics in the joints of the lower extremity during Tai Chi is an essential step in revealing the nature of Tai Chi exercise. Methods Twelve healthy subjects, six young and six elderly, who had been practicing Tai Chi for at least three months, participated in the study. The kinematics of Tai Chi gait (TCG) and normal gait (NG) were measured using a marker-based motion analysis system and two biomechanical force plates. Anthropometric measurements of the subjects were taken and used to estimate joint center locations. The resultant joint forces and moments due to the external loads (ground reaction forces, mass) were calculated using the inverse dynamics approach. Due to the slow nature of TCG, a quasi-static condition was assumed. An ANOVA was performed on all dependent variables to determine the main effects of gait (TCG vs. NG) and group (young vs. elderly). Results (1) The peak forces were significantly greater during TCG than during NG in all three joints of the lower extremity (Ankle = 86.86 ± 26.81%BW vs. 62.25 ± 18.91 %BW; Knee 58.51 ± 14.24 %BW vs. 37.90 ± 5.97 %BW; Hip = 43.62 ± 9.31 %BW vs. 23.64 ± 8.63 %BW). (2) During TCG, the peak forces were significantly greater in the young group than in the elderly group in all three joints (Ankle = 100.91 ± 26.85 %BW vs. 72.82 ± 26.77 %BW; Knee = 66.65 ± 16.08 %BW vs. 50.38 ± 12.40 %BW; Hip = 43.62 ± 9.31 %BW vs. 30.87 ± 15.56 %BW). (3) The peak forces occurred more toward the medial/lateral axis and at a greater angle from anterior 0 during TCG than during NG in all three joints (Ankle = +/- 99.37 ± 10.49° vs. +/- 84.0 ± 18.73°; Knee = + 35.54 ± 11.08° vs. +/- 6.64 ± 3.01°; Hip = 96.81 ± 28.54° vs. -51.41 ± 33.93°). There was no significant difference between the young and elderly subjects in the angles of the peak forces in all three joints. (4) The peak-to-peak range of moments was significantly greater during TCG than during NG in all three joints (Ankle abduction/adduction 3.46 ± 4.52 %BM vs. 0.78 ± 0.52 %BM; Knee flexion/extension 2.01 ± 1.18 %BM vs. 1.25 ± 0.81 %BM; Knee abduction/adduction 8.12 + 4.43 %BM vs. 3.71 + 1.61 %BM; Hip flexion/extension = 8.84 ± 3.01 %BM vs. 5.33 ± 2.11 %BM; Hip internal/ external rotation 3.81 + 1.80 %BM vs. 1.23 + 0.41). There were no significant differences between the young and elderly subjects in the peak-to-peak range of moments. (5) The magnitude of the peak moment and the amount contributed by each directional axis were significantly different between TCG and NG. There were no significant differences between the young and elderly groups in this variable. (6) There was significant interaction in a group by gait comparison of both the temporal and spatial variables. Conclusions The results of this study could have a significant impact on many health care fields. Quantifying the biomechanical characteristics of TCG may help physicians determine whether Tai Chi may be helpful or harmful to a patient. This study also provides a foundation of methodology for future research of the biomechanics of Tai Chi to help gain an understanding of why Tai Chi is an effective exercise for strength, flexibility and balance.