Abstract
Background: Short successive periods of physical inactivity occur throughout life and contribute considerably to the age-related loss of skeletal muscle mass. The maintenance of muscle mass during brief periods of disuse is required to prevent functional decline and maintain metabolic health. Objective: To assess whether daily leucine supplementation during a short period of disuse can attenuate subsequent muscle loss in vivo in humans. Methods: Thirty healthy (22 +/- 1 y) young males were exposed to a 7-day unilateral knee immobilization intervention by means of a full leg cast with (LEU, n = 15) or without (CON, n = 15) daily leucine supplementation (2.5 g leucine, three times daily). Prior to and directly after immobilization, quadriceps muscle cross-sectional area (computed tomography (CT) scan) and leg strength (one-repetition maximum (1-RM)) were assessed. Furthermore, muscle biopsies were taken in both groups before and after immobilization to assess changes in type I and type II muscle fiber CSA. Results: Quadriceps muscle cross-sectional area (CSA) declined in the CON and LEU groups (p <0.01), with no differences between the two groups (from 7712 +/- 324 to 7287 +/- 305 mm(2) and from 7643 +/- 317 to 7164 +/- 328 mm(2); p = 0.61, respectively). Leg muscle strength decreased from 56 +/- 4 to 53 +/- 4 kg in the CON group and from 63 +/- 3 to 55 +/- 2 kg in the LEU group (main effect of time p <0.01), with no differences between the groups (p = 0.052). Type I and II muscle fiber size did not change significantly over time, in both groups (p > 0.05). Conclusions: Free leucine supplementation with each of the three main meals (7.5 g/d) does not attenuate the decline of muscle mass and strength during a 7-day limb immobilization intervention.
Original language | English |
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Article number | 635 |
Number of pages | 12 |
Journal | Nutrients |
Volume | 10 |
Issue number | 5 |
DOIs | |
Publication status | Published - May 2018 |
Keywords
- limb immobilization
- countermeasures
- amino acid
- strength
- ESSENTIAL AMINO-ACIDS
- MYOFIBRILLAR PROTEIN-SYNTHESIS
- HUMAN QUADRICEPS MUSCLE
- BED-REST
- OLDER-ADULTS
- DISUSE ATROPHY
- ELDERLY-MEN
- IN-VIVO
- NUTRITIONAL STRATEGIES
- RESISTANCE EXERCISE