De Smet Stefan, van Herpt Paul, D'Hulst Gommaar, Van Thienen Ruud, Van Leemputte Marc, Hespel Peter
Department of Kinesiology, Exercise Physiology Research Group, KU LeuvenLeuven, Belgium.
Athletic Performance Center, Bakala Academy, KU LeuvenLeuven, Belgium.
Front Physiol. 2017 May 31;8:347. doi: 10.3389/fphys.2017.00347. eCollection 2017.
In the setting of "living high," it is unclear whether high-intensity interval training (HIIT) should be performed "low" or "high" to stimulate muscular and performance adaptations. Therefore, 10 physically active males participated in a 5-week "live high-train low or high" program (TR), whilst eight subjects were not engaged in any altitude or training intervention (CON). Five days per week (15.5 h per day), TR was exposed to normobaric hypoxia simulating progressively increasing altitude of ~2,000-3,250 m. Three times per week, TR performed HIIT, administered as unilateral knee-extension training, with one leg in normobaric hypoxia (4,300 m; TR) and with the other leg in normoxia (TR). "Living high" elicited a consistent elevation in serum erythropoietin concentrations which adequately predicted the increase in hemoglobin mass ( = 0.78, < 0.05; TR: +2.6%, < 0.05; CON: -0.7%, > 0.05). Muscle oxygenation during training was lower in TR vs. TR ( < 0.05). Muscle homogenate buffering capacity and pH-regulating protein abundance were similar between pretest and posttest. Oscillations in muscle blood volume during repeated sprints, as estimated by oscillations in NIRS-derived tHb, increased from pretest to posttest in TR (80%, < 0.01) but not in TR (50%, = 0.08). Muscle capillarity (15%) as well as repeated-sprint ability (8%) and 3-min maximal performance (10-15%) increased similarly in both legs ( < 0.05). Maximal isometric strength increased in TR (8%, < 0.05) but not in TR (~4%, > 0.05). In conclusion, muscular and performance adaptations were largely similar following normoxic vs. hypoxic HIIT. However, hypoxic HIIT stimulated adaptations in isometric strength and muscle perfusion during intermittent sprinting.
在“高住低练”的情况下，高强度间歇训练（HIIT）是应该“低强度”还是“高强度”进行以刺激肌肉和运动表现适应尚不清楚。因此，10名身体活跃的男性参与了一项为期5周的“高住低练或高练”计划（TR组），而8名受试者未进行任何海拔或训练干预（CON组）。每周5天（每天约15.5小时），TR组暴露于模拟海拔逐渐升高至约2000 - 3250米的常压低氧环境中。每周3次，TR组进行HIIT，形式为单侧膝关节伸展训练，一条腿处于常压低氧环境（约4300米；TR组），另一条腿处于常氧环境（TR组）。“高住低练”使血清促红细胞生成素浓度持续升高，这充分预测了血红蛋白量的增加（r = 0.78，P < 0.05；TR组：增加2.6%，P < 0.05；CON组：减少0.7%，P > 0.05）。与常氧HIIT（TR组）相比，低氧HIIT（TR组）训练期间的肌肉氧合较低（P < 0.05）。肌肉匀浆缓冲能力和pH调节蛋白丰度在测试前和测试后相似。通过近红外光谱衍生的总血红蛋白（tHb）振荡估计的重复冲刺期间肌肉血容量振荡，TR组从测试前到测试后增加（约80%，P < 0.01），而TR组增加不明显（约50%，P = 0.08）。双腿的肌肉毛细血管密度（约15%）以及重复冲刺能力（约8%）和3分钟最大运动表现（约10 - 15%）的增加相似（P < 0.05）。最大等长力量在TR组增加（约8%，P < 0.05），而在TR组增加不明显（约4%，P > 0.05）。总之，常氧与低氧HIIT后的肌肉和运动表现适应在很大程度上相似。然而，低氧HIIT刺激了等长力量和间歇冲刺期间肌肉灌注的适应。
