Neural control of anticipatory braking and lateral balance predicts fall risk in older adults: BMI-dependent mechanisms

Introduction Falls are a leading cause of disability among older adults, and neural control is increasingly recognized as a critical risk factor. In this prospective cohort study, we investigated whether deceleration during terminal swing (DCEL), and medial-lateral velocity zero crossing count (VZCC), reflecting anticipatory braking and lateral balance control, predict future falls, and whether body mass index (BMI) moderates these associations. A total of 380 older adults were assessed and stratified by BMI (overweight: ≥ 25 kg/m 2 ). Methods Fallers ( n = 68) and non-fallers ( n = 312) were identified prospectively over a 24-month follow-up period. Gait was measured using inertial measurement units (IMUs) during 14-meter walks. Results Compared to non-fallers, fallers were older (75.1 ± 4.31 vs. 73.4 ± 4.51 years, p = 0.002), had more prior falls, more negative DCEL values (−10.57 ± 15.61 vs. -5.08 ± 16.39 cm/s, p = 0.010), and higher VZCC (4.96 ± 2.59 vs. 4.29 ± 1.31, p = 0.023). In multivariate models, age, prior falls, DCEL, VZCC, and the BMI × DCEL interaction predicted fall risk. DCEL predicted falls only in individuals with normal weight (OR = 0.533, 95% CI = 0.368–0.770, p = 0.001), whereas VZCC predicted falls across all BMI levels. Gait parameters reflecting neural control predict fall risk, with effects moderated by BMI. Discussion Anticipatory braking control is critical for individuals with normal weight, whereas lateral instability elevates fall risk regardless of BMI. These findings highlight the value of BMI-stratified fall assessments and targeted interventions.