Mixed
Two weeks of unilateral limb immobilization induces a coordinate down-regulation of mitochondrial bioenergetic and carbohydrate metabolism pathways in human skeletal muscle, leading to significant reductions in muscle strength and cross-sectional area.
If you must immobilize a limb (e.g., cast, brace) for two weeks, expect significant strength and size loss, driven largely by a shutdown of mitochondrial energy production. This metabolic suppression happens very early (within 48 hours). To mitigate this, active rehabilitation of the non-immobilized limb and nutritional strategies supporting mitochondrial health may be considered, though the primary intervention is minimizing immobilization time.
As a group, genes involved in mitochondrial bioenergetics and carbohydrate metabolism were predominant features at both 48 H and 14 D... Muscle cross sectional area (,5%) and strength (10–20%) were significantly reduced in men and women (,5% and 10–20%, respectively) after 14 D of immobilization.
Why this rating
Randomized controlled trial with a relatively large cohort (N=24) and multiple time points, though short duration.
Source
Limb Immobilization Induces a Coordinate Down-Regulation of Mitochondrial and Other Metabolic Pathways in Men and Women
Arkan Abadi et al. · PLoS ONE · 2009
DOI 10.1371/journal.pone.0006518
More from this paper
- Protein ubiquitination and the expression of atrogenes (atrogin-1, MuRF-1) are significantly increased early (48 hours) during immobilization but return to baseline levels by 14 days, suggesting a transient role for this pathway in short-term human muscle atrophy.Good
- Immobilization significantly reduces the phosphorylation of mTOR at 48 hours, indicating early suppression of anabolic signaling, which correlates with the down-regulation of PGC-1alpha and mitochondrial biogenesis.Good
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