Analysis of postural control through nonlinear methods in older adults: a randomized controlled trial

Background Human balance and body orientation are regulated by the postural control system, which plays a critical role in stability, particularly with advancing age. Objective This study examined the effects of a sensorimotor training program on postural control in older adults (55–80 years), investigating how targeted exercise may influence postural regulation. Methods A total of 86 community-dwelling individuals aged 55 and 80 years participated in the study and were randomly assigned to a Control Group (CG, n = 43; average age: 73.50 ± 6.08 years) and an Experimental Group (EG, n = 43; average age: 72.40 ± 7.03 years). The intervention lasted six months, with sessions twice a week, and consisted of six exercise circuits focused on sensorimotor stimulation. Each circuit included eight physical exercises, progressively adjusted in difficulty over time, according to predefined performance-based criteria and under the supervision of a trained instructor to ensure appropriate individual adaptation. Results Analysis of covariance (ANCOVA) analyses adjusted for baseline values revealed selective between-group differences. Approximate Entropy (ApEn) showed a significant effect in mediolateral sway under eyes-open conditions (ApEn_ML_OE: F = 8.7, p = 0.004, η 2 p = 0.10). Lyapunov Exponent (LyE) showed significant effects under eyes-closed conditions in both anteroposterior and mediolateral directions (LyE_AP_CE: F = 4.0, p = 0.049; LyE_ML_CE: F = 13.6, p = 0.001), indicating improved local dynamic stability. No significant between-group differences were observed for Detrended Fluctuation Analysis (DFA). Substantial inter-individual variability was observed across participants. Conclusions Sensorimotor training was associated with selective changes in nonlinear postural control measures, particularly under reduced visual input. However, responses were heterogeneous, indicating that effects were not uniform across individuals. These findings suggest that targeted exercise interventions may modulate specific aspects of postural control in older adults, with potential relevance for balance regulation and fall prevention.