Dietary protein adequacy and lower body versus whole body resistive training in older humans
Dietary protein adequacy and lower body versus whole body resistive training in older humans
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DOI：
10.1113/jphysiol.2002.020685
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发表时间：
2002-07-15
影响因子：
5.5
通讯作者：
Evans, WJ
中科院分区：
文献类型：
--
作者：
Campbell, WW;Trappe, TA;Evans, WJ
本研究评估了久坐或进行抗阻训练 (RT) 的老年人长期摄入美国推荐膳食摄入量 (RDA) 蛋白质对身体成分、骨骼肌大小和蛋白质代谢的影响，以及训练的肌肉群数量是否影响肌肉肥大对 RT 的反应。 12 名男性和 17 名女性（年龄范围 54-78 岁）完成了这项为期 14 周的控制饮食和运动研究。在整个研究过程中，每位受试者完全食用每日能量丰富的菜单，该菜单提供的 RDA 为 0.8 g 蛋白质 kg(-1) day(-1)。从研究第 3 周到第 14 周（RT1-RT12 周），10 名受试者（4 名男性，6 名女性）进行了全身 RT (WBRT)，9 名受试者（4 名男性，5 名女性）进行了下半身 RT (LBRT)，10 名受试者（4 名男性，6 名女性）保持久坐 (SED)。 LBRT 和 WBRT 组均进行膝关节伸展和屈曲练习，WBRT 组还进行胸部推举和手臂拉动练习（每次练习 3 组，达到一次重复次数最大值的 80%，每周 3 天，持续 12 周）。从第 2 周（基线）到 RT12 周，LBRT 和 WBRT 组中训练的肌肉群的肌肉力量有所增加，而 SED 组中没有变化。从基线到 RT12 周，这些体重稳定的老年人的全身肌肉质量和蛋白质矿物质质量没有变化，去脂质量 (P = 0.004) 和体内水分总量 (P = 0.013) 减少，体脂百分比增加 (P = 0.0 11)，与分组无关。 RT 引起的大腿中部肌肉面积增加（来自计算机断层扫描）在 LBRT 和 WBRT 组中相当（分别为 2.13 +/- 1.26 cm(2) 和 2.17 +/- 1.24 cm(2)），并且与 SED 组不同，后者肌肉面积减少（-1.74 +/- 0.57 cm(2)；按时间分组 P < 0.05）。从基线到RT12周，24小时尿总氮排泄量减少（P < 0.001），氮平衡从接近平衡转变为正，全身亮氨酸氧化（来自L-[C-13]亮氨酸的输注）减少（P < 0.05），净（吸收后与餐后）亮氨酸平衡（P < 0.05）从接近平衡增加到正，随着时间的推移，三者之间的反应没有差异组。总之，训练的肌肉群数量不会影响老年人的全身蛋白质代谢或 RT 引起的肌肉肥大。大多数这些数据与成功适应蛋白质 RDA 一致。然而，研究应该继续质疑所有受试者中观察到的去脂质量和全身水分的减少，以及 SED 组中大腿中部肌肉面积的减少是否是生理调节，以及蛋白质的 RDA 是否可能稍微不足以让老年人维持骨骼肌。
This study assessed the effects of long-term consumption of the United States Recommended Dietary Allowance (RDA) for protein by older people who were sedentary or performed resistive training (RT) on body composition, skeletal muscle size and protein metabolism, and if the number of muscle groups trained influenced the muscle hypertrophy response to RT. Twelve men and 17 women (age range 54-78 years) completed this 14 week controlled diet and exercise study. Throughout the study, each subject completely consumed daily euenergetic menus that provided the RDA of 0.8 g protein kg(-1) day(-1). From study weeks 3-14 (weeks RT1-RT12), 10 subjects (four men, six women) performed whole body RT (WBRT), nine subjects (four men, five women) performed lower body RT (LBRT) and 10 subjects (four men, six women) remained sedentary (SED). Both the LBRT and WBRT groups performed knee extension and flexion exercises, and the WBRT group also performed chest press and arm pull exercises (three sets per exercise at 80% of one repetition maximum, 3 days per week for 12 weeks). From week 2 (baseline) to week RT12, muscle strength increased in muscle groups trained in the LBRT and WBRT groups, and was not changed in the SED group. From baseline to week RT12, whole body muscle mass and protein-mineral mass were not changed, fat-free mass (P = 0.004) and total body water (P = 0.013) were decreased, and percentage body fat was increased (P = 0.0 11) in these weight-stable older people, independent of group assignment. The RT-induced increases in mid-thigh muscle area (from computed tomography scans) were comparable in the LBRT and WBRT groups (2.13 +/- 1.26 cm(2) and 2.17 +/- 1.24 cm(2), respectively), and were different from those in the SED group, which lost muscle area (-1.74 +/- 0.57 cm(2); group-by-time P < 0.05). From baseline to week RT12,24 h urinary total nitrogen excretion decreased (P < 0.001), nitrogen balance shifted from near equilibrium to positive, whole body leucine oxidation (from the infusion Of L-[C-13]leucine) decreased (P < 0.05) and net (postabsorptive vs. postprandial) leucine balance (P < 0.05) increased from near equilibrium to positive, with no differences in responses over time among the three groups. In conclusion, the number of muscle groups trained did not influence whole body protein metabolism or RT-induced muscle hypertrophy in older people. Most of these data are consistent with a successful adaptation to the RDA for protein. However, research should continue to question whether the decreases in fat-free mass and total body water observed in all subjects, and the decrease in mid-thigh muscle area in the SED group, are physiological accommodations, and whether the RDA for protein might be marginally inadequate for older people to maintain skeletal muscle.