Inclusion Criteria:  aged 70-80 years, community-dwelling, able to walk 500 m without assistance or use of walking aid and regularly walking >5000 steps per day, MMSE >24, BMI 20-35 kg·m2 (i.e. not underweight or severely obese), no serious cardiovascular or musculoskeletal disease, no risk factors for deep-vein thrombosis (e.g. blood clotting disorder, obesity, bowel diseases, personal or family history of DVT etc.), non-smoker, provision of informed consent.  Exclusion Criteria:  Underlying diseases likely to limit lifespan and/or intervention safety. Contraindication for physical exercise or physical tests identified during physician's examination, unwilling/unable to track daily step counts using accelerometer, excessive and regular use of alcohol (more than 7 units per week for women and 14 for men) difficulty in communication due to severe vision or hearing problems unwilling to provide consent or accept randomization into either study group