Feasibility and potential efficacy of high-intensity stepping training in variable contexts in subacute and chronic stroke

Background. Previous data suggest that the amount and aerobic intensity of stepping training may improve walking poststroke. Recent animal and human studies suggest that training in challenging and variable contexts can also improve locomotor function. Such practice may elicit substantial stepping errors, although alterations in locomotor strategies to correct these errors could lead to improved walking ability. Objective. This unblinded pilot study was designed to evaluate the feasibility and preliminary efficacy of providing stepping practice in variable, challenging contexts (tasks and environments) at high aerobic intensities in participants >6 months and 1-6 months post-stroke. Methods. A total of 25 participants (gait speeds <0.9 m/s with no more than moderate assistance) participated in ≤40 training sessions (duration of 1 hour) within 10 weeks. Stepping training in variable, challenging contexts was performed at 70% to 80% heart rate reserve, with feasibility measures of total steps/session, ability to achieve targeted intensities, patient tolerance, dropouts, and adverse events. Gait speed, symmetry, and 6-minute walk were measured every 4 to 5 weeks or 20 sessions, with a 3-month follow-up (F/U). Results. In all, 22 participants completed ≥4 training weeks, averaging 2887 ± 780 steps/session over 36 ± 5.8 sessions. Self-selected (0.38 ± 0.27 to 0.66 ± 0.35 m/s) and fastest speed (0.51 ± 0.40 to 0.99 ± 0.58 m/s), paretic single-limb stance (20% ± 5.9% to 25% ± 6.4%), and 6-minute walk (141 ± 99 to 260 ± 146 m) improved significantly at posttraining. Conclusions. This preliminary study suggests that stepping training at high aerobic intensities in variable contexts was tolerated by participants poststroke, with significant locomotor improvements. Future studies should delineate the relative contributions of amount, intensity, and variability of stepping training to maximize outcomes.