The study will investigate safety, usability, feasibility and preliminary efficacy of perturbation-based training in participants post-stroke and older adults with mild balance deficits. Both group will receive three weks of training. The primary outcome measure will be derived from laboratory-induced falls.

Two convenience samples will be recruited to serve as self-controls, 20 post-stroke adults and 30 community-dwelling older adults. Participants post stroke will be recruited after discharge from their regular rehabilitation. Each subject will undergo individually customised perturbation-based training sessions with safety harnesses. The participants will be assessed at four time points: at baseline, after 3 weeks (at the beginning of training), at the end of 3-week training, and at 3-week follow-up. Safety, usability and efficacy of training will be evaluated using slip-, trip- and platform-movement-based perturbations induced by a Stewart platform and dual-belt treadmill, whereby the perturbation strength that can be reliably counteracted will be recorded, and using standardised clinical outcome measures.

Inclusion Criteria for both arms:

• ability for independent community walking without aids;
• sufficient cognitive, visual, and communication abilities for study participation.

Exclusion Criteria for both arms:

• musculoskeletal impairments;
• cardiovascular health-related problems;
• other health conditions that could interfere with the training.

Additional Inclusion Criteria for post-stroke patients:

• discharge from their regular rehabilitation;
• at least 6 months after first unilateral cerebral stroke;
• 18 to 70 years of age;
• absence of additional neurologic conditions.

Additional Inclusion Criteria for older adults:

• age 65 to 75 years;
• no known health-related problems significantly affecting balance and walking.