Muscle inactivity leads to muscle atrophy. Leucine is known to inhibit protein degradation and to promote protein synthesis in skeletal muscle. We tested the ability of a high-protein diet enriched with branched-chain amino acids (BCAAs) to prevent muscle atrophy during long-term bed rest (BR). We determined body composition (using dual energy x-ray absorptiometry) at baseline and every 2-weeks during 60 days of BR in 16 healthy young women. Nitrogen (N) balance was assessed daily as the difference between N intake and N urinary excretion. The subjects were randomized into two groups: one received a conventional diet (1.1 +/- 0.03 g protein/kg, 4.9 +/- 0.3 g leucine per day) and the other a high protein, BCAA-enriched regimen (1.6 +/- 0.03 g protein-amino acid/kg, 11.4 +/- 0.6 g leucine per day). There were significant BR and BR x diet interaction effects on changes in lean body mass (LBM) and N balance throughout the experimental period (repeated measures ANCOVA). During the first 15 days of BR, lean mass decreased by 4.1 +/- 0.9 and 2.4 +/- 2.1% (p < 0.05) in the conventional and high protein-BCAA diet groups, respectively, while at the end of the 60-day BR, LBM decreased similarly in the two groups by 7.4 +/- 0.7 and 6.8 +/- 2.4%. During the first 15 days of BR, mean N balance was 2.5 times greater (p < 0.05) in subjects on the high protein-BCAA diet than in those on the conventional diet, while we did not find significant differences during the following time intervals. In conclusion, during 60 days of BR in females, a high protein-BCAA diet was associated with an early protein-LBM sparing effect, which ceased in the medium and long term.

Early lean mass sparing effect of high-protein diet with excess leucine during long-term bed rest in women

Giordano, Mauro;
2022

Abstract

Muscle inactivity leads to muscle atrophy. Leucine is known to inhibit protein degradation and to promote protein synthesis in skeletal muscle. We tested the ability of a high-protein diet enriched with branched-chain amino acids (BCAAs) to prevent muscle atrophy during long-term bed rest (BR). We determined body composition (using dual energy x-ray absorptiometry) at baseline and every 2-weeks during 60 days of BR in 16 healthy young women. Nitrogen (N) balance was assessed daily as the difference between N intake and N urinary excretion. The subjects were randomized into two groups: one received a conventional diet (1.1 +/- 0.03 g protein/kg, 4.9 +/- 0.3 g leucine per day) and the other a high protein, BCAA-enriched regimen (1.6 +/- 0.03 g protein-amino acid/kg, 11.4 +/- 0.6 g leucine per day). There were significant BR and BR x diet interaction effects on changes in lean body mass (LBM) and N balance throughout the experimental period (repeated measures ANCOVA). During the first 15 days of BR, lean mass decreased by 4.1 +/- 0.9 and 2.4 +/- 2.1% (p < 0.05) in the conventional and high protein-BCAA diet groups, respectively, while at the end of the 60-day BR, LBM decreased similarly in the two groups by 7.4 +/- 0.7 and 6.8 +/- 2.4%. During the first 15 days of BR, mean N balance was 2.5 times greater (p < 0.05) in subjects on the high protein-BCAA diet than in those on the conventional diet, while we did not find significant differences during the following time intervals. In conclusion, during 60 days of BR in females, a high protein-BCAA diet was associated with an early protein-LBM sparing effect, which ceased in the medium and long term.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11591/485224
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