The present study will seek the quantify the simultaneous muscle protein synthesis and breakdown response with and without amino acid provision in humans following 2 days of immobilisation.

Inclusion Criteria:

• Male
• 18-40 years of age
• Body mass index between 18.5 and 30

Exclusion Criteria:

• Any diagnosed metabolic impairment (e.g. type 1 or 2 Diabetes)
• Any diagnosed cardiovascular disease (e.g. deep vein thrombosis) or hypertension
• Chronic use of any prescribed or over the counter pharmaceuticals (that may modulate muscle protein metabolism)
• A personal or family history of epilepsy, seizures or schizophrenia
• Any known disorders in muscle metabolism
• Regular use of nutritional supplements
• Allergy to lidocaine
• Allergy to one or multiple amino acids
• Recent (within the last 6 months) or current musculoskeletal injury (e.g. leg fracture) as these could be exacerbated by the intervention e.g. unilateral leg immobilisation, or mean the participant is unable to use crutches.
• Having received or ingested a stable isotope tracer in the past