NUTRIM, School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, THE NETHERLANDS.
Institute of Sports and Exercise Studies, HAN University of Applied Sciences, Nijmegen, THE NETHERLANDS.
Med Sci Sports Exerc. 2019 Jun;51(6):1137-1145. doi: 10.1249/MSS.0000000000001899.
Combining blood flow restriction (BFR) with exercise can stimulate skeletal muscle hypertrophy. Recent observations in an animal model suggest that BFR performed without exercise can also induce anabolic effects. We assessed the effect of BFR performed both with and without low-load resistance-type exercise (LLRE) on in vivo myofibrillar protein synthesis rates in young men.
Twenty healthy young men (age = 24 ± 1 yr, body mass index = 22.9 ± 0.6 kg·m) were randomly assigned to remain in resting condition (REST ± BFR; n = 10) or to perform LLRE (LLRE ± BFR at 20% one-repetition maximum; n = 10), combined with two 5-min cycles of single leg BFR. Myofibrillar protein synthesis rates were assessed during a 5-h post-BFR period by combining a primed continuous L-[ring-C6]phenylalanine infusion with the collection of blood samples, and muscle biopsies from the BFR leg and the contralateral control leg. The phosphorylation status of anabolic signaling (mammalian target of rapamycin pathway) and metabolic stress (acetyl-CoA carboxylase)-related proteins, as well as the mRNA expression of genes associated with skeletal muscle mass regulation, was assessed in the collected muscle samples.
Under resting conditions, no differences in anabolic signaling or myofibrillar protein synthesis rates were observed between REST + BFR and REST (0.044% ± 0.004% vs 0.043% ± 0.004% per hour, respectively; P = 0.683). By contrast, LLRE + BFR increased myofibrillar protein synthesis rates by 10% ± 5% compared with LLRE (0.048% ± 0.005% vs 0.043% ± 0.004% per hour, respectively; P = 0.042). Furthermore, compared with LLRE, LLRE + BFR showed higher phosphorylation status of acetyl-CoA carboxylase and 4E-BP1 as well as the elevated mRNA expression of MuRF1 (all P < 0.05).
BFR does not increase myofibrillar protein synthesis rates in healthy young men under resting conditions. When combined with LLRE, BFR increases postexercise myofibrillar protein synthesis rates in vivo in humans.
结合血流限制（BFR）和运动可以刺激骨骼肌肥大。最近在动物模型中的观察表明，不进行运动的 BFR 也可以诱导合成代谢效应。我们评估了在年轻男性中同时进行 BFR 和低负荷抵抗型运动（LLRE）对肌原纤维蛋白合成率的影响。
20 名健康年轻男性（年龄=24±1 岁，体重指数=22.9±0.6kg·m）随机分为静息状态下（REST+BFR；n=10）或进行 LLRE（20%一次重复最大负荷的 LLRE+BFR；n=10），同时进行双腿 BFR 的两个 5 分钟循环。通过将脉冲式连续 L-[环-C6]苯丙氨酸输注与血液样本收集以及 BFR 腿和对侧对照腿的肌肉活检相结合，在 BFR 后 5 小时期间评估肌原纤维蛋白合成率。收集的肌肉样本中评估了合成代谢信号（雷帕霉素靶蛋白途径）和代谢应激（乙酰辅酶 A 羧化酶）相关蛋白的磷酸化状态，以及与骨骼肌质量调节相关的基因的 mRNA 表达。
在静息状态下，REST+BFR 和 REST 之间的合成代谢信号或肌原纤维蛋白合成率没有差异（分别为 0.044%±0.004% vs 0.043%±0.004%/小时，P=0.683）。相比之下，LLRE+BFR 使肌原纤维蛋白合成率增加了 10%±5%，与 LLRE 相比（0.048%±0.005% vs 0.043%±0.004%/小时，P=0.042）。此外，与 LLRE 相比，LLRE+BFR 显示乙酰辅酶 A 羧化酶和 4E-BP1 的磷酸化状态更高，MuRF1 的 mRNA 表达增加（均 P<0.05）。
在静息状态下，BFR 不会增加健康年轻男性的肌原纤维蛋白合成率。当与 LLRE 结合使用时，BFR 会增加人体运动后的肌原纤维蛋白合成率。
