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Short-term muscle disuse induces a rapid and sustained decline in daily myofibrillar protein synthesis rates
Kilroe, Sean P. Fulford, Jonathan Holwerda, Andrew M. Jackman, Sarah R. Lee, Benjamin P. Gijsen, Annemie P. van Loon, Luc J. C. Wall, Benjamin T.
Kilroe, Sean P.
Fulford, Jonathan
Holwerda, Andrew M.
Jackman, Sarah R.
Lee, Benjamin P.
Gijsen, Annemie P.
van Loon, Luc J. C.
Wall, Benjamin T.
Abstract
Short-term muscle disuse has been reported to lower both postabsorptive and postprandial myofibrillar protein synthesis rates. This study assessed the impact of disuse on daily myofibrillar protein synthesis rates following short-term (2 and 7 days) muscle disuse under free living conditions. Thirteen healthy young men (age: 20 ± 1 yr; BMI: 23 ± 1 kg/m−2) underwent 7 days of unilateral leg immobilization via a knee brace, with the nonimmobilized leg acting as a control. Four days before immobilization participants ingested 400 mL of 70% deuterated water, with 50-mL doses consumed daily thereafter. Upper leg bilateral MRI scans and muscle biopsies were collected before and after 2 and 7 days of immobilization to determine quadriceps volume and daily myofibrillar protein synthesis rates. Immobilization reduced quadriceps volume in the immobilized leg by 1.7 ± 0.3 and 6.7 ± 0.6% after 2 and 7 days, respectively, with no changes in the control leg. Over the 1-wk immobilization period, myofibrillar protein synthesis rates were 36 ± 4% lower in the immobilized (0.81 ± 0.04%/day) compared with the control (1.26 ± 0.04%/day) leg (P < 0.001). Myofibrillar protein synthesis rates in the control leg did not change over time (P = 0.775), but in the immobilized leg they were numerically lower during the 0- to 2-day period (16 ± 6%, 1.11 ± 0.09%/day, P = 0.153) and were significantly lower during the 2- to 7-day period (44 ± 5%, 0.70 ± 0.06%/day, P < 0.001) when compared with the control leg. We conclude that 1 wk of muscle disuse induces a rapid and sustained decline in daily myofibrillar protein synthesis rates in healthy young men.
Keywords
atrophy, disuse, immobilization, muscle protein synthesis rates, skeletal muscle
Date
2019
Type
Journal article
Journal
American Journal of Physiology: Endocrinology and Metabolism
Book
Volume
318
Issue
2
Page Range
E117-E130
Article Number
ACU Department
Centre for Exercise and Nutrition
Faculty of Health Sciences
Faculty of Health Sciences
Collections
Relation URI
Source URL
Event URL
Open Access Status
Published as green open access
License
File Access
Open
Controlled
Controlled