This study aims to evaluate the feasibility of a high-intensity functional exercise program with simultaneous cognitive challenge (HIFE+cog) among older people at risk of falls. The evaluation design and intervention development will be assessed with the following specific aims:

1. To investigate the acceptability and safety of the HIFE+cog program in older people at risk of falls, and the methods used in the study by evaluating recruitment, compliance with the intervention, severity of adverse events reported, and participant experiences.
2. To measure key outcome variables, including completion rates, missing data, estimates, variances, and 95% confidence intervals for between-group differences.

The study is designed as a randomized controlled pilot trial. Eligible participants will be randomized to either the intervention group (HIFE+cog) or the active control group (HIFE) to partake in individually tailored exercise, supervised and progressed by a physiotherapist, two times per week for 3 months.

Inclusion Criteria:

• aged 75 years or older
• moderate risk of falling (feeling unsteady or afraid of falling, or having fallen in the past year, with a self-selected gait speed ≤0,8 m/s or TUG >15 s without walking aid)
• can walk independently indoors, without a walking aid
• can walk 500m independently outdoors, with or without a walking aid

Exclusion Criteria:

• a high fall risk (≥2 falls in the past year, serious injury e.g. hip fracture from a fall in the past year requiring medical care, or inability to get up from the floor after a fall)
• Mini-Mental State Examination (MMSE) score <24 or dementia diagnosis
• a medical condition that may affect participation in high-intensity gait, balance, and leg strength exercise, or other movement-related conditions affecting exercise or tests (e.g., pain, dizziness, visual or hearing impairment)

The datasets generated and analysed during the study will not publicly available to protect the participants' confidentiality (in accordance with The General Data Protection Regulation, European Union Regulation) but are available from the principal investigator on reasonable request.

Outcome assessors will be blinded to group allocation. Participants will receive repeated instructions not to disclose their group allocation to the assessors.