The impact of Tai Chi's "Xuling Dingjin" posture on lumbar biomechanics during stair descent. - Duan, Yiting; Liu, Haibin; Jiang, Jian; Liu, Liqing; Gao, Fan; Li, Suheng; Yang, Yulong; Yang, Shuye; Yan, Shudong (Frontiers in Sports & Active Living, 2025)