Effects of Tai Chi training on the physical and mental health status in patients with chronic obstructive pulmonary disease: a systematic review and meta-analysis - Guo, Chengyao; Xiang, Guiling; Xie, Liang; Liu, Zilong; Zhang, Xiaomin; Wu, Qinhan; Li, Shanqun; Wu, Yan (Journal of Thoracic Disease, 2020)