Maintenance of body's skeletal muscle is key to a healthy older age. However, as we age we lose on average 1-2% of our muscle each year. In order to slow this loss we need to understand fully the mechanisms regulating muscle mass with ageing. In this project we aim to determine these mechanisms using a new novel technique of 'heavy' water ingestion, which will allow us to measure multiple aspects of skeletal muscle mass control during normal everyday activities in young and old individuals over a period of 6 weeks. We will also determine the influence of resistance exercise training during this period in offsetting declines in muscle with ageing using this method

Inclusion Criteria:

• Young (18-30y) and old men (65-75y) who are generally healthy and recreationally active

Exclusion Criteria:

• Active cardiovascular disease
• Cerebrovascular disease including previous stroke, aneurysm (large vessel or intracranial)
• Respiratory disease including pulmonary hypertension or COPD
• Hyper/ hypo parathyroidism, hyper/ hypothyroidism, Cushing's disease, diabetes
• Active inflammatory bowel disease
• Renal disease
• Malignancy
• Recent steroid treatment (within 6 mo), or hormone replacement therapy
• Clotting dysfunction
• Musculoskeletal or neurological disorders
• Any disease requiring long-term drug prescriptions, including statins