Schroer Adam B, Saunders Michael J, Baur Daniel A, Womack Christopher J, Luden Nicholas D
Dept. of Kinesiology, James Madison University, Harrisonburg, VA.
Int J Sport Nutr Exerc Metab. 2014 Oct;24(5):507-15. doi: 10.1123/ijsnem.2013-0173. Epub 2014 Jun 17.
Previous studies reported that adding protein (PRO) to carbohydrate (CHO) solutions enhances endurance performance. The ergogenic effect may be a function of additional protein/amino acid calories, but this has not been examined. In addition, although supplemental L-alanine (ALA) is readily oxidized during exercise, the subsequent impact on metabolism and prolonged endurance performance is unknown. The purpose of this investigation was to independently gauge the impact of whey PRO hydrolysate and ALA supplementation on performance and various physiological parameters. Eight cyclists (age: 22.3 ± 5.6 yr, weight: 70.0 ± 8.0 kg, VO2max: 59.4 ± 4.9 ml · kg(-1) · min(-1)) performed 120 min of constant-load cycling (55% of peak power) followed by a 30-km time trial (TT) under placebo (PLA), PRO, and ALA conditions. Magnitude-based qualitative inferences were applied to evaluate treatment differences and data are presented as percent difference between treatments ± 90% confidence limit. Both ALA (2.1 ± 2.7%) and PRO intake (-2.1 ± 2.2%) possibly harmed performance compared with PLA. Of interest, heart rate was possibly lower with ALA than PLA at 20- (-2.7 ± 3.4%) and 120-min (-1.7 ± 2.9%) of constant-load cycling and the serum interleukin-6 (IL-6) response to 120 min of cycling was likely attenuated with PRO compared with PLA (PLA, 6.6 ± 3.7 fold vs. PRO, 2.9 ± 1.8 fold). In addition, blood glucose levels were lower with PRO than PLA at 20- (-8.8 ± 2.3%; very likely) and 120-min (-4.9 ± 4.6%; likely) of constant-load cycling. Although ALA intake appears to lower HR and PRO ingestion dampens the IL-6 response to exercise, the ingestion of PRO (without CHO) or ALA does not enhance, and may actually impair, performance following prolonged cycling.
以往研究报道，在碳水化合物（CHO）溶液中添加蛋白质（PRO）可提高耐力表现。这种促力效应可能是额外蛋白质/氨基酸热量的作用，但尚未得到验证。此外，虽然补充L-丙氨酸（ALA）在运动过程中易于被氧化，但其对代谢和耐力表现的后续影响尚不清楚。本研究的目的是独立评估乳清蛋白水解物和补充ALA对运动表现及各种生理参数的影响。八名自行车运动员（年龄：22.3±5.6岁，体重：70.0±8.0千克，最大摄氧量：59.4±4.9毫升·千克⁻¹·分钟⁻¹）在安慰剂（PLA）、PRO和ALA条件下进行120分钟的恒定负荷骑行（峰值功率的55%），随后进行30公里计时赛（TT）。采用基于量级的定性推断来评估处理差异，数据以处理间的百分比差异±90%置信区间表示。与PLA相比，ALA（2.1±2.7%）和PRO摄入（-2.1±2.2%）可能对运动表现有害。有趣的是，在恒定负荷骑行20分钟（-2.7±3.4%）和120分钟（-1.7±2.9%）时，ALA组的心率可能低于PLA组，与PLA相比，PRO组对120分钟骑行的血清白细胞介素-6（IL-6）反应可能减弱（PLA组为6.6±3.7倍，PRO组为2.9±1.8倍）。此外，在恒定负荷骑行20分钟（-8.8±2.3%；极有可能）和120分钟（-4.9±4.6%；可能）时，PRO组的血糖水平低于PLA组。虽然摄入ALA似乎会降低心率，摄入PRO会减弱运动对IL-6的反应，但摄入PRO（无CHO）或ALA并不能提高，实际上可能会损害长时间骑行后的运动表现。
