Clark Sally A, Aughey Robert J, Gore Christopher J, Hahn Allan G, Townsend Nathan E, Kinsman Tahnee A, Chow Chin-Moi, McKenna Michael J, Hawley John A
School of Medical Sciences, RMIT University, Bundoora, Victoria 3083, Australia.
J Appl Physiol (1985). 2004 Feb;96(2):517-25. doi: 10.1152/japplphysiol.00799.2003. Epub 2003 Sep 26.
We determined the effect of 20 nights of live high, train low (LHTL) hypoxic exposure on lactate kinetics, monocarboxylate lactate transporter proteins (MCT1 and MCT4), and muscle in vitro buffering capacity (betam) in 29 well-trained cyclists and triathletes. Subjects were divided into one of three groups: 20 consecutive nights of hypoxic exposure (LHTLc), 20 nights of intermittent hypoxic exposure [four 5-night blocks of hypoxia, each interspersed with 2 nights of normoxia (LHTLi)], or control (Con). Rates of lactate appearance (Ra), disappearance (Rd), and oxidation (Rox) were determined from a primed, continuous infusion of l-[U-14C]lactic acid tracer during 90 min of steady-state exercise [60 min at 65% peak O2 uptake (VO(2 peak)) followed by 30 min at 85% VO(2 peak)]. A resting muscle biopsy was taken before and after 20 nights of LHTL for the determination of betam and MCT1 and MCT4 protein abundance. Ra during the first 60 min of exercise was not different between groups. During the last 25 min of exercise at 85% VO(2 peak), Ra was higher compared with exercise at 65% of VO(2 peak) and was decreased in LHTLc (P < 0.05) compared with the other groups. Rd followed a similar pattern to Ra. Although Rox was significantly increased during exercise at 85% compared with 65% of VO(2 peak), there were no differences between the three groups or across trials. There was no effect of hypoxic exposure on betam or MCT1 and MCT4 protein abundance. We conclude that 20 consecutive nights of hypoxia exposure decreased whole body Ra during intense exercise in well-trained athletes. However, muscle markers of lactate metabolism and pH regulation were unchanged by the LHTL intervention.
我们测定了20个“高住低练”（LHTL）低氧暴露夜晚对29名训练有素的自行车运动员和铁人三项运动员的乳酸动力学、单羧酸乳酸转运蛋白（MCT1和MCT4）以及肌肉体外缓冲能力（betam）的影响。受试者被分为三组之一：连续20个夜晚进行低氧暴露（LHTLc）、20个夜晚进行间歇性低氧暴露[四个5晚的低氧阶段，每个阶段穿插2个常氧夜晚（LHTLi）]或对照组（Con）。在90分钟的稳态运动期间[60分钟以65%的峰值摄氧量（VO₂峰值），随后30分钟以85%的VO₂峰值]，通过一次性连续输注l-[U-¹⁴C]乳酸示踪剂来测定乳酸生成速率（Ra）、消失速率（Rd）和氧化速率（Rox）。在LHTL的20个夜晚前后进行静息肌肉活检，以测定betam以及MCT1和MCT4蛋白丰度。运动前60分钟内的Ra在各组之间没有差异。在以85%的VO₂峰值进行运动的最后25分钟内，与以65%的VO₂峰值进行运动相比，Ra更高，并且与其他组相比，LHTLc组的Ra降低了（P<0.05）。Rd呈现与Ra相似的模式。尽管与以65%的VO₂峰值进行运动相比，在以85%的VO₂峰值进行运动期间Rox显著增加，但三组之间或各试验之间没有差异。低氧暴露对betam或MCT1和MCT4蛋白丰度没有影响。我们得出结论，连续20个夜晚的低氧暴露会降低训练有素的运动员在高强度运动期间的全身Ra。然而，LHTL干预并未改变乳酸代谢和pH调节的肌肉标志物。
