Non-steady-state modelling reveals reduced skeletal muscle protein synthesis as the primary driver of disuse-atrophy in young, healthy females.

What was studied

A controlled mechanistic study examined whether muscle disuse reduces synthesis or increases breakdown, accounting for shrinking muscle-protein pools.

Who / model studied

Fourteen healthy young women, average age 21.

Studied dose & schedule

One leg underwent 10 days of unloading; the opposite leg performed resistance exercise. Deuterated water, MRI and mathematical models assessed turnover and muscle size.

What the study found

Unloading reduced muscle volume and mixed/myofibrillar protein synthesis. Model-derived breakdown did not increase. Accounting for the shrinking protein pool preserved this conclusion. Integrated synthesis in the exercised leg did not rise above baseline.

Limitations & context

Abstract-based assessment with no numerical effect magnitudes or confidence intervals available. Small, short study; breakdown was estimated, not directly observed. Results do not establish mechanisms in every illness or prove that resistance exercise cannot stimulate synthesis.

Read summary source ↗ · Prepared 10/28/2026 · AI-assisted, source-based summary