Biomechanical analysis of Tai Chi gait and lower limb joint stability: impact on balance control

Abstract

Background Although Tai Chi has demonstrated efficacy in improving balance and preventing falls, the underlying biomechanical mechanisms remain incompletely understood. Objectives This study aimed to examine biomechanical mechanisms associated with Tai Chi practice in relation to lower limb joint stability and balance control Methods A cross-sectional comparative study enrolled 64 participants aged 55-70 years (32 long-term Tai Chi practitioners and 32 age-matched controls). Comprehensive biomechanical assessments included 3D motion capture (200 Hz), force plate measurements (2000 Hz), 16-channel surface electromyography, and standardized balance tests. Primary outcomes were joint stability indices, center of pressure parameters, and balance performance scores. Multiple regression and mediation analyses identified relationships between joint stability mechanisms and balance outcomes. Results Compared to controls, Tai Chi practitioners demonstrated significantly greater ankle dynamic stiffness (23.8 +/- 2.4 vs. 19.5 +/- 2.8 Nm/kg/rad, p < 0.001, d = 1.72), enhanced hip-knee coordination (0.78 +/- 0.06 vs. 0.65 +/- 0.09, p < 0.001, d = 1.63), and 32.1% higher neuromuscular efficiency at the ankle joint. These adaptations correlated strongly with superior balance performance, including 32.3% smaller center of pressure excursion area during single-leg stance (p < 0.001) and 36.2% faster time-to-stabilization after perturbations (p < 0.001). Mediation analysis revealed that ankle proprioceptive acuity and dynamic joint stiffness regulation accounted for 58.4% of the relationship between Tai Chi experience and balance performance. Conclusions Long-term Tai Chi practice is associated with specific neuromuscular adaptations characterized by proximal-to-distal muscle activation sequencing, selective joint stiffness modulation, and enhanced anticipatory postural adjustments. These biomechanical mechanisms provide evidence-based foundations for optimizing Tai Chi training protocols and integrating Tai Chi principles into fall-prevention and rehabilitation programs.