Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+ , The Netherlands.
Human Health and Nutritional Sciences, University of Guelph , Guelph, Ontario , Canada.
Am J Physiol Endocrinol Metab. 2019 Mar 1;316(3):E536-E545. doi: 10.1152/ajpendo.00378.2018. Epub 2019 Jan 15.
Short periods of bed rest lead to the loss of muscle mass and quality. It has been speculated that dietary feeding pattern may have an impact upon muscle protein synthesis rates and, therefore, modulate the loss of muscle mass and quality. We subjected 20 healthy men (age: 25 ± 1 yr, body mass index: 23.8 ± 0.8 kg/m) to 1 wk of strict bed rest with intermittent (4 meals/day) or continuous (24 h/day) enteral tube feeding. Participants consumed deuterium oxide for 7 days before bed rest and throughout the 7-day bed rest period. Prior to and immediately after bed rest, lean body mass (dual energy X-ray absorptiometry), quadriceps cross-sectional area (CSA; CT), maximal oxygen uptake capacity (V̇o), and whole body insulin sensitivity (hyperinsulinemic-euglycemic clamp) were assessed. Muscle biopsies were collected 7 days before, 1 day before, and immediately after bed rest to assess muscle tracer incorporation. Bed rest resulted in 0.3 ± 0.3 vs. 0.7 ± 0.4 kg lean tissue loss and a 1.1 ± 0.6 vs. 0.8 ± 0.5% decline in quadriceps CSA in the intermittent vs. continuous feeding group, respectively (both P < 0.05), with no differences between groups (both P > 0.05). Moreover, feeding pattern did not modulate the bed rest-induced decline in insulin sensitivity (-46 ± 3% vs. 39 ± 3%; P < 0.001) or V̇o (-2.5 ± 2.2 vs. -8.6 ± 2.2%; P < 0.010) (both P > 0.05). Myofibrillar protein synthesis rates during bed rest did not differ between the intermittent and continuous feeding group (1.33 ± 0.07 vs. 1.50 ± 0.13%/day, respectively; P > 0.05). In conclusion, dietary feeding pattern does not modulate the loss of muscle mass or the decline in metabolic health during 1 wk of bed rest in healthy men.
短期卧床休息会导致肌肉质量和肌肉量减少。人们推测，饮食喂养模式可能会影响肌肉蛋白质合成率，从而调节肌肉质量和肌肉量的减少。我们让 20 名健康男性（年龄：25±1 岁，体重指数：23.8±0.8 kg/m）接受为期 1 周的严格卧床休息，同时接受间歇性（4 餐/天）或连续性（24 小时/天）肠内管饲。参与者在卧床休息前 7 天和整个卧床休息期间都摄入重水。在卧床休息之前和卧床休息之后立即，评估瘦体重（双能 X 射线吸收法）、股四头肌横截面积（CSA；CT）、最大摄氧量能力（V̇o）和全身胰岛素敏感性（高胰岛素-正常血糖钳夹）。卧床休息前 7 天、1 天前和卧床休息后立即采集肌肉活检，以评估肌肉示踪剂掺入情况。卧床休息导致间歇性喂养组的瘦组织损失为 0.3±0.3 kg，股四头肌 CSA 下降 1.1±0.6%，而连续性喂养组的瘦组织损失为 0.7±0.4 kg，股四头肌 CSA 下降 0.8±0.5%（均 P<0.05），但两组之间无差异（均 P>0.05）。此外，喂养模式并未调节卧床休息引起的胰岛素敏感性下降（-46±3%对-39±3%；P<0.001）或 V̇o 下降（-2.5±2.2 对-8.6±2.2%；P<0.010）（均 P>0.05）。卧床休息期间，间歇性和连续性喂养组的肌原纤维蛋白合成率无差异（分别为 1.33±0.07%和 1.50±0.13%/天；P>0.05）。总之，在健康男性卧床休息 1 周期间，饮食喂养模式不会调节肌肉质量的减少或代谢健康的下降。
