This non-blinded, three-armed randomized controlled trial aimed at comparing the effects of volitional step training under stable and unstable conditions on balance, mobility and strength adaptations.
Fifty-one healthy and active older adults (age=69.4 ± 5.6 years; BMI=27.4 ± 4.6, physical activity= 9.2 ± 5.1 h/week) were allocated to either volitional stepping (VOL), volitional stepping under unstable conditions (VOL+US) or a control group (CON) using the minimization method. Participants underwent eight weeks of exergames based step training with three sessions per week. Pre- and Post-testing included reactive balance (postural sway upon perturbation), functional balance (Y-balance test) and mobility (timed up and go test) to compare the effects of both intervention groups. Strength was tested using the heel rise test and isometric leg extension and leg curl assessment to compare transfer effects of the intervention groups.
Data of 45 participants was finally analyzed. Adherence was 87 ± 5% in the VOL+US group and 86 ± 6% in the VOL group. No adverse events occurred. Increased reactive balance was observed in VOL+US only (p < 0.05, standard mean difference (SMD)=0.3) whereas both intervention groups improved functional balance (p < 0.05, SMD=0.5?1.0). Only VOL+US led to improved functional mobility performance under dual-task conditions (p < 0.05, SMD=?0.4). Both VOL+US and VOL significantly improved calf strength endurance (p < 0.05, SMD=0.7?0.8), whereas isometric strength of the thigh muscles revealed no significant changes (p > 0.05). Explosive strength (rate of force development) showed insignificant but medium interaction effects of the leg extensors in favor of VOL+US (p=0.08, η2p =0.12, SMD=0.2).
Volitional step training is an appealing and effective training tool to improve functional balance and calf strength in healthy older adults. Unstable volitional stepping seems to be superior in improving reactive balance and functional mobility under dual-task conditions. It appears that the volitional stepping under unstable conditions requires motor skills relevant for preventing falls since it is more tasks specific when compared to volitional stepping under stable conditions.