Muscle protein fractional synthetic rate

Method

Fractional synthetic rate of skeletal muscle protein measured by stable-isotope tracer incorporation into a muscle biopsy, expressed as percent per hour. The protein fraction — myofibrillar, sarcoplasmic or mixed muscle — is recorded on the edge, since the fractions respond differently to the same feeding.

The method is part of the endpoint identity. Studies measuring the same quantity by a different method are held as separate endpoints.

Notes

41 papers, 17 randomised trials. This is an acute mechanistic measurement over hours, NOT a measure of muscle accrual: a supplement can raise it in a single postprandial period without changing lean mass over weeks, and the two must never be treated as the same finding. claim_horizon on such an edge is acute.