Section of Integrative Physiology, Department of Nutrition, Exercise and Sports (NEXS), University of Copenhagen, Copenhagen, Denmark.
Institute for Health and Sport (IHES), Victoria University, Melbourne, VIC, Australia.
J Physiol. 2019 May;597(9):2421-2444. doi: 10.1113/JP277657. Epub 2019 Mar 28.
Training with blood flow restriction (BFR) is a well-recognized strategy for promoting muscle hypertrophy and strength. However, its potential to enhance muscle function during sustained, intense exercise remains largely unexplored. In the present study, we report that interval training with BFR augments improvements in performance and reduces net K release from contracting muscles during high-intensity exercise in active men. A better K regulation after BFR-training is associated with an elevated blood flow to exercising muscles and altered muscle anti-oxidant function, as indicated by a higher reduced to oxidized glutathione (GSH:GSSG) ratio, compared to control, as well as an increased thigh net K release during intense exercise with concomitant anti-oxidant infusion. Training with BFR also invoked fibre type-specific adaptations in the abundance of Na ,K -ATPase isoforms (α , β , phospholemman/FXYD1). Thus, BFR-training enhances performance and K regulation during intense exercise, which may be a result of adaptations in anti-oxidant function, blood flow and Na ,K -ATPase-isoform abundance at the fibre-type level.
We examined whether blood flow restriction (BFR) augments training-induced improvements in K regulation and performance during intense exercise in men, and also whether these adaptations are associated with an altered muscle anti-oxidant function, blood flow and/or with fibre type-dependent changes in Na ,K -ATPase-isoform abundance. Ten recreationally-active men (25 ± 4 years, 49.7 ± 5.3 mL kg min ) performed 6 weeks of interval cycling, where one leg trained without BFR (control; CON-leg) and the other trained with BFR (BFR-leg, pressure: ∼180 mmHg). Before and after training, femoral arterial and venous K concentrations and artery blood flow were measured during single-leg knee-extensor exercise at 25% (Ex1) and 90% of thigh incremental peak power (Ex2) with i.v. infusion of N-acetylcysteine (NAC) or placebo (saline) and a resting muscle biopsy was collected. After training, performance increased more in BFR-leg (23%) than in CON-leg (12%, P < 0.05), whereas K release during Ex2 was attenuated only from BFR-leg (P < 0.05). The muscle GSH:GSSG ratio at rest and blood flow during exercise was higher in BFR-leg than in CON-leg after training (P < 0.05). After training, NAC increased resting muscle GSH concentration and thigh net K release during Ex2 only in BFR-leg (P < 0.05), whereas the abundance of Na ,K -ATPase-isoform α in type II (51%), β in type I (33%), and FXYD1 in type I (108%) and type II (60%) fibres was higher in BFR-leg than in CON-leg (P < 0.05). Thus, training with BFR elicited greater improvements in performance and reduced thigh K release during intense exercise, which were associated with adaptations in muscle anti-oxidant function, blood flow and Na ,K -ATPase-isoform abundance at the fibre-type level.
血流限制（BFR）训练是促进肌肉肥大和力量的一种公认策略。然而，其在持续高强度运动中增强肌肉功能的潜力在很大程度上尚未得到探索。在本研究中，我们报告了 BFR 间歇训练可以提高男性在高强度运动中的表现并减少收缩肌肉中的净 K 释放。与对照组相比，BFR 训练后更好的 K 调节与运动肌肉中的血流量增加和肌肉抗氧化功能改变有关，表现为还原型谷胱甘肽（GSH）：氧化型谷胱甘肽（GSSG）的比值升高，以及在伴有抗氧化剂输注的高强度运动期间大腿净 K 释放增加。BFR 训练还引起了 Na+，K+-ATPase 同工型（α，β，磷叶立德/FXYD1）在纤维类型上的特异性适应性变化。因此，BFR 训练可增强高强度运动中的表现和 K 调节，这可能是由于抗氧化功能、血流和 Na+，K+-ATPase-同工型丰度在纤维类型水平上的适应性变化所致。
我们研究了 BFR 是否可以增强男性在高强度运动中的训练诱导的 K 调节和表现的改善，以及这些适应性是否与改变的肌肉抗氧化功能、血流以及 Na+，K+-ATPase-同工型丰度有关。10 名有经验的男性（25±4 岁，49.7±5.3mL·kg-1·min-1）进行了 6 周的间歇骑车运动，其中一条腿不进行 BFR 训练（对照；CON-腿），另一条腿进行 BFR 训练（BFR-腿，压力：约 180mmHg）。在训练前后，在单腿膝关节伸展运动中测量股动脉和静脉 K 浓度以及动脉血流量，运动强度分别为 25%（Ex1）和大腿递增峰值功率的 90%（Ex2），并静脉内输注 N-乙酰半胱氨酸（NAC）或安慰剂（生理盐水），同时采集休息时的肌肉活检。训练后，BFR-腿的表现提高了 23%，而 CON-腿的表现提高了 12%（P<0.05），而仅在 BFR-腿中，Ex2 期间的 K 释放减少（P<0.05）。与 CON-腿相比，BFR-腿在训练后的静息肌肉 GSH：GSSG 比值和运动期间的血流量更高（P<0.05）。训练后，仅在 BFR-腿中，NAC 增加了 Ex2 期间的静息肌肉 GSH 浓度和大腿净 K 释放（P<0.05），而 Na+，K+-ATPase-同工型α在 II 型（51%），β在 I 型（33%）和 FXYD1 在 I 型（108%）和 II 型（60%）纤维中的丰度均高于 CON-腿（P<0.05）。因此，BFR 训练可引起表现的更大改善，并减少高强度运动中大腿的 K 释放，这与纤维类型水平上的肌肉抗氧化功能、血流和 Na+，K+-ATPase-同工型丰度的适应性变化有关。
