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Acta Physiol (Oxf). 2014 Mar;210(3):600-11. doi: 10.1111/apha.12190. Epub 2013 Dec 5.

Substantial skeletal muscle loss occurs during only 5 days of disuse.

Author information

1
Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism Maastricht University Medical Centre, Maastricht, the Netherlands.

Abstract

AIM:

The impact of disuse on the loss of skeletal muscle mass and strength has been well documented. Given that most studies have investigated muscle atrophy after more than 2 weeks of disuse, few data are available on the impact of shorter periods of disuse. We assessed the impact of 5 and 14 days of disuse on skeletal muscle mass, strength and associated intramuscular molecular signalling responses.

METHODS:

Twenty-four healthy, young (23 ± 1 year) males were subjected to either 5 (n = 12) or 14 (n = 12) days of one-legged knee immobilization using a full leg cast. Before and immediately after the immobilization period, quadriceps muscle cross-sectional area (CSA), leg lean mass and muscle strength were assessed, and biopsies were collected from the vastus lateralis.

RESULTS:

Quadriceps muscle CSA declined from baseline by 3.5 ± 0.5 (P < 0.0001) and 8.4 ± 2.8% (P < 0.001), leg lean mass was reduced by 1.4 ± 0.7 (P = 0.07) and 3.1 ± 0.7% (P < 0.01) and strength was decreased by 9.0 ± 2.3 (P < 0.0001) and 22.9 ± 2.6% (P < 0.001) following 5 and 14 days of immobilization respectively. Muscle myostatin mRNA expression doubled following immobilization (P < 0.05) in both groups, while the myostatin precursor isoform protein content decreased after 14 days only (P < 0.05). Muscle MAFBx mRNA expression increased from baseline by a similar magnitude following either 5 or 14 days of disuse, whereas MuRF1 mRNA expression had increased significantly only after 5 days.

CONCLUSION:

We conclude that even short periods of muscle disuse can cause substantial loss of skeletal muscle mass and strength and are accompanied by an early catabolic molecular signalling response.

KEYWORDS:

disuse atrophy; immobilization; myostatin; skeletal muscle

PMID:
24168489
DOI:
10.1111/apha.12190
[Indexed for MEDLINE]

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