Exercise mitigates disuse atrophy by building muscle reserve
In women undergoing limb immobilization, prehabilitation increased quadriceps area by 6.7% before disuse, preserving more post-immobilization muscle despite identical 3.2% relative losses.
medRxiv
In a randomized trial reported in a medRxiv preprint, 54 healthy younger and older women completed four weeks of supervised resistance training or no exercise before eight days of unilateral limb immobilization. Prehabilitation increased quadriceps cross-sectional area by 6.7%, maximal voluntary contraction by 15.2%, and muscle fiber cross-sectional area by 17.7% before disuse. Immobilization subsequently reduced quadriceps area by 3.2% over five days and strength by approximately 20%, with similar relative losses occurring in both groups. Because trained participants built reserve beforehand, quadriceps area remained higher after immobilization and after four weeks of subsequent rehabilitation. Prehabilitation did not blunt the molecular response to disuse, which altered over 7,000 genes linked to inflammation and proteolysis. Results were similar in younger and older women.
Why it matters
Muscle loss during bed rest or injury severely impairs recovery and functional independence in older adults. These findings suggest pre-emptive training protects against clinical disuse by building a buffer of muscle mass and strength rather than altering the underlying biology of atrophy.
Caveats
The findings are from a preprint that evaluated a brief period of disuse exclusively in healthy female participants.
The paper
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Amanda El Khoury, Helena L. Christiansen, Frederik Hvid Linden, René B. Svensson, Stig Peter Magnusson, Peter Schjerling, Michael Kjær,University of Copenhagen
medRxiv · 27 Sep 2026 · Preprint, not peer-reviewed