在老年人休息和抗阻运动后摄入大豆分离蛋白对肌原纤维蛋白合成的影响。

Myofibrillar protein synthesis following ingestion of soy protein isolate at rest and after resistance exercise in elderly men.

机构信息

Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, 1280 Main St, West, Hamilton, ON, Canada, L8S 4K1.

出版信息

Nutr Metab (Lond). 2012 Jun 14;9(1):57. doi: 10.1186/1743-7075-9-57.

BACKGROUND

Increased amino acid availability stimulates muscle protein synthesis, however, aged muscle appears less responsive to the anabolic effects of amino acids when compared to the young. We aimed to compare changes in myofibrillar protein synthesis (MPS) in elderly men at rest and after resistance exercise following ingestion of different doses of soy protein and compare the responses to those we previously observed with ingestion of whey protein isolate.

METHODS

Thirty elderly men (age 71 ± 5 y) completed a bout of unilateral knee-extensor resistance exercise prior to ingesting no protein (0 g), or either 20 g or 40 g of soy protein isolate (0, S20, and S40 respectively). We compared these responses to previous responses from similar aged men who had ingested 20 g and 40 g of whey protein isolate (W20 and W40). A primed constant infusion of L-[1-13 C]leucine and L-[ring-13 C6]phenylalanine and skeletal muscle biopsies were used to measure whole-body leucine oxidation and MPS over 4 h post-protein consumption in both exercised and non-exercised legs.

RESULTS

Whole-body leucine oxidation increased with protein ingestion and was significantly greater for S20 vs. W20 (P = 0.003). Rates of MPS for S20 were less than W20 (P = 0.02) and not different from 0 g (P = 0.41) in both exercised and non-exercised leg muscles. For S40, MPS was also reduced compared with W40 under both rested and post-exercise conditions (both P < 0.005); however S40 increased MPS greater than 0 g under post-exercise conditions (P = 0.04).

CONCLUSIONS

The relationship between protein intake and MPS is both dose and protein source-dependent, with isolated soy showing a reduced ability, as compared to isolated whey protein, to stimulate MPS under both rested and post-exercise conditions. These differences may relate to the lower postprandial leucinemia and greater rates of amino acid oxidation following ingestion of soy versus whey protein.

背景

增加氨基酸的供应可以刺激肌肉蛋白质的合成，然而，与年轻人相比，老年肌肉对氨基酸的合成代谢作用的反应似乎较低。我们旨在比较不同剂量的大豆蛋白摄入后，老年男性静息和抗阻运动后肌原纤维蛋白合成（MPS）的变化，并将这些反应与我们之前观察到的摄入乳清蛋白分离物后的反应进行比较。

方法

30 名老年男性（年龄 71±5 岁）在进行单侧膝关节伸肌抗阻运动之前，分别摄入 0g（0 组）、20g 或 40g 的大豆蛋白分离物（S20 和 S40 组）。我们将这些反应与之前摄入 20g 和 40g 乳清蛋白分离物（W20 和 W40 组）的相似年龄男性的反应进行了比较。通过脉冲式持续输注 L-[1-13C]亮氨酸和 L-[ring-13C6]苯丙氨酸以及骨骼肌活检，在摄入蛋白质后 4 小时内测量全身亮氨酸氧化和 MPS，同时测量运动和非运动腿的肌肉。

结果

蛋白质摄入后全身亮氨酸氧化增加，S20 组显著高于 W20 组（P=0.003）。S20 组的 MPS 率低于 W20 组（P=0.02），与 0g 组无差异（P=0.41），在运动和非运动腿肌肉中均如此。对于 S40 组，在休息和运动后两种情况下，MPS 均低于 W40 组（均 P<0.005）；然而，在运动后条件下，S40 组增加 MPS 高于 0g 组（P=0.04）。