Department of Public Health, Aarhus University, Dalgas Ave. 4, 8000, Aarhus C, Denmark.
Arla Foods Ingredients Group P/S, Viby J, 8260, Denmark.
J Int Soc Sports Nutr. 2020 Jan 28;17(1):7. doi: 10.1186/s12970-020-0338-z.
Deliberately training with reduced carbohydrate availability, a paradigm coined training low, has shown to promote adaptations associated with improved aerobic capacity. In this context researchers have proposed that protein may be ingested prior to training as a means to enhance the protein balance during exercise without spoiling the effect of the low carbohydrate availability. Accordingly, this is being practiced by world class athletes. However, the effect of protein intake on muscle protein metabolism during training low has not been studied. This study aimed to examine if protein intake prior to exercise with reduced carbohydrate stores benefits muscle protein metabolism in exercising and non-exercising muscles.
Nine well-trained subjects completed two trials in random order both of which included a high-intensity interval ergometer bike ride (day 1), a morning (day 2) steady state ride (90 min at 65% VOpeak, 90ss), and a 4-h recovery period. An experimental beverage was consumed before 90ss and contained either 0.5 g whey protein hydrolysate [WPH]/ kg lean body mass or flavored water [PLA]. A stable isotope infusion (L-[ring-C]-phenylalanine) combined with arterial-venous blood sampling, and plasma flow rate measurements were used to determine forearm protein turnover. Myofibrillar protein synthesis was determined from stable isotope incorporation into the vastus lateralis.
Forearm protein net balance was not different from zero during 90ss exercise (nmol/100 ml/min, PLA: 0.5 ± 2.6; WPH: 1.8, ± 3.3) but negative during the 4 h recovery (nmol/100 ml/min, PLA: - 9.7 ± 4.6; WPH: - 8.7 ± 6.5); no interaction (P = 0.5) or main effect of beverage (P = 0.11) was observed. Vastus lateralis myofibrillar protein synthesis rates were increased during 90ss exercise (+ 0.02 ± 0.02%/h) and recovery (+ 0.02 ± 0.02%/h); no interaction (P = 0.3) or main effect of beverage (P = 0.3) was observed.
We conclude that protein ingestion prior to endurance exercise in the energy- and carbohydrate-restricted state does not increase myofibrillar protein synthesis or improve net protein balance in the exercising and non-exercising muscles, respectively, during and in the hours after exercise compared to ingestion of a non-caloric control.
clinicaltrials.gov, NCT01320449. Registered 10 May 2017 - Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03147001.
刻意减少碳水化合物的摄入进行训练，这种训练模式被称为低碳训练，已被证明可以促进与有氧能力提高相关的适应。在这种情况下，研究人员提出，在训练前摄入蛋白质可能是一种增强运动中蛋白质平衡而不破坏低碳水化合物供应效果的方法。因此，世界级运动员都在采用这种方法。然而，低碳训练期间蛋白质摄入对肌肉蛋白质代谢的影响尚未得到研究。本研究旨在探讨在低碳状态下运动前摄入蛋白质是否有益于运动和非运动肌肉的肌肉蛋白质代谢。
9 名训练有素的受试者以随机顺序完成了两项试验，均包括高强度间歇自行车骑行（第 1 天）、上午（第 2 天）稳态骑行（90 分钟，65% VOpeak，90 秒）和 4 小时恢复期。在 90 秒前饮用实验饮料，其中含有 0.5g 乳清蛋白水解物[WPH]/kg 去脂体重或调味水[PLA]。稳定同位素输注（L-[环-C]-苯丙氨酸）与动脉-静脉血液取样和血浆流量测量相结合，用于确定前臂蛋白质周转率。从稳定同位素掺入到股外侧肌来确定肌原纤维蛋白合成。
前臂蛋白质净平衡在 90 秒运动期间与零没有差异（nmol/100ml/min，PLA：0.5±2.6；WPH：1.8，±3.3），但在 4 小时恢复期为负（nmol/100ml/min，PLA：-9.7±4.6；WPH：-8.7±6.5）；没有观察到相互作用（P=0.5）或饮料的主要影响（P=0.11）。股外侧肌肌原纤维蛋白合成率在 90 秒运动期间增加（+0.02±0.02%/h）和恢复期间（+0.02±0.02%/h）；没有观察到相互作用（P=0.3）或饮料的主要影响（P=0.3）。
我们得出结论，与摄入非热量对照相比，在能量和碳水化合物受限状态下进行耐力运动前摄入蛋白质不会增加运动和非运动肌肉在运动中和运动后数小时的肌原纤维蛋白合成或改善蛋白质净平衡。
clinicaltrials.gov，NCT01320449。2017 年 5 月 10 日注册-回顾性注册，https://clinicaltrials.gov/ct2/show/NCT03147001。
