Leucine partially protects muscle mass and function during bed rest in middle-aged adults
Leucine partially protects muscle mass and function during bed rest in middle-aged adults
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DOI：
10.3945/ajcn.115.112359
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发表时间：
2016-02-01
影响因子：
7.1
通讯作者：
Paddon-Jones, Douglas
中科院分区：
文献类型：
--
作者：
English, Kirk L.;Mettler, Joni A.;Paddon-Jones, Douglas
背景：缺乏身体活动会导致老年人肌肉质量和功能迅速丧失。中年人几乎没有表现出衰老的表型迹象，但可能比年轻人更容易缺乏活动。目的：目的是确定亮氨酸（一种翻译起始和骨骼肌蛋白合成（MPS）的刺激剂）是否可以在卧床休息期间保护骨骼肌健康。设计：我们使用了一项随机、双盲、安慰剂对照试验来评估中年人骨骼肌蛋白合成（MPS）、细胞信号、身体成分和骨骼肌功能的变化成人（n = 19；年龄 +/- SEM：52 +/- 1 岁）在卧床休息 14 天期间对亮氨酸补充（LEU 组：0.06 g . kg(-1) .膳食(-1)）或丙氨酸对照（CON 组）的反应。结果：卧床休息使吸收后 MPS 降低了 30% +/- 9%（CON 组）和 10% +/- 10% （LEU 组）（时间的主效应，P < 0.05），但在 MPS 或细胞信号传导方面未检测到组间变化（组 x 时间交互作用）之间的差异。亮氨酸保护膝关节伸肌峰值扭矩（CON 与 LEU 组相比：-15% +/- 2% 和 -7% +/- 3%；组 x 时间交互作用，P < 0.05）和耐力（CON 与 LEU 相比：-14% +/- 3% 和 -2% +/- 4%；组 x 时间交互作用，P < 0.05），防止体脂百分比的增加（组 x 时间交互作用，P < 0.05），并减少卧床休息 7 天（CON 与 LEU 相比：-1.5 +/- 0.3 和 -0.8 +/- 0.3 kg；组 x 时间交互作用，P < 0.05）后全身瘦体重损失，但卧床休息 14 天（CON 与 LEU 比较：-1.5 +/- 0.3 和 -1.0 +/- 0.3 kg）后没有全身瘦体重损失。卧床休息 14 天后，亮氨酸还能保持肌肉质量（峰值扭矩/kg 腿部瘦体重）（CON 与 LEU 相比：-9% +/- 2% 和 +1% +/- 3%；组 x 时间交互作用，P < 0.05）。 结论：卧床休息对中年成人的肌肉代谢、质量和功能具有深远的负面影响。在相对短暂的身体不活动期间，补充亮氨酸可以部分保护肌肉健康。该试验在 ClinicalTrials.gov 上注册为 NCT00968344。
Background: Physical inactivity triggers a rapid loss of muscle mass and function in older adults. Middle-aged adults show few phenotypic signs of aging yet may be more susceptible to inactivity than younger adults.Objective: The aim was to determine whether leucine, a stimulator of translation initiation and skeletal muscle protein synthesis (MPS), can protect skeletal muscle health during bed rest.Design: We used a randomized, double-blind, placebo-controlled trial to assess changes in skeletal MPS, cellular signaling, body composition, and skeletal muscle function in middle-aged adults (n = 19; age +/- SEM: 52 +/- 1 y) in response to leucine supplementation (LEU group: 0.06 g . kg(-1) . meal(-1)) or an alanine control (CON group) during 14 d of bed rest.Results: Bed rest decreased postabsorptive MPS by 30% +/- 9% (CON group) and by 10% +/- 10% (LEU group) (main effect for time, P < 0.05), but no differences between groups with respect to pre-post changes (group x time interactions) were detected for MPS or cell signaling. Leucine protected knee extensor peak torque (CON compared with LEU group: -15% +/- 2% and -7% +/- 3%; group x time interaction, P < 0.05) and endurance (CON compared with LEU: -14% +/- 3% and -2% +/- 4%; group x time interaction, P < 0.05), prevented an increase in body fat percentage (group x time interaction, P < 0.05), and reduced whole-body lean mass loss after 7 d (CON compared with LEU: -1.5 +/- 0.3 and -0.8 +/- 0.3 kg; group x time interaction, P < 0.05) but not 14 d (CON compared with LEU: -1.5 +/- 0.3 and -1.0 +/- 0.3 kg) of bed rest. Leucine also maintained muscle quality (peak torque/kg leg lean mass) after 14 d of bed-rest inactivity (CON compared with LEU: -9% +/- 2% and +1% +/- 3%; group x time interaction, P < 0.05).Conclusions: Bed rest has a profoundly negative effect on muscle metabolism, mass, and function in middle-aged adults. Leucine supplementation may partially protect muscle health during relatively brief periods of physical inactivity. This trial was registered at clinicaltrials.gov as NCT00968344.