Mixed
Unilateral immobilization or unloading causes profound muscle atrophy and metabolic risk factors in the immobilized limb, but these adaptations are specific to that limb and do not transfer to the non-immobilized control limb.
If you have to immobilize one limb (e.g., in a cast), expect that specific limb to lose muscle mass and strength, but know that your other limb will remain healthy and strong. This local specificity means you can maintain overall body function and use the healthy limb to support yourself without risking systemic decline.
For instance, 14 d of single-leg bracing in young men results in a significant decline in isometric torque, thigh cross sectional area, and type I and II cross sectional area in the immobilized limb, with no detectable change in the contralateral limb... Moreover, there were no detectable changes in the maximal activities of citrate synthase and beta-hydroxyacyl CoA dehydrogenase in the control leg.
Why this rating
Supported by multiple citations within the review.
Source
Investigating human skeletal muscle physiology with unilateral exercise models: when one limb is more powerful than two
Martin J. MacInnis et al. · Applied Physiology Nutrition and Metabolism · 2017
DOI 10.1139/apnm-2016-0645
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