Berger Nicolas J A, McNaughton Lars R, Keatley Simon, Wilkerson Daryl P, Jones Andrew M
Department of Exercise and Sport Science, Manchester Metropolitan University, Hassall Road, Alsager, UK.
Med Sci Sports Exerc. 2006 Nov;38(11):1909-17. doi: 10.1249/01.mss.0000233791.85916.33.
The influence of metabolic alkalosis (ALK) on pulmonary O2 uptake (pVO2) kinetics during high-intensity cycle exercise is controversial. The purpose of this study was to examine the influence of ALK induced by sodium bicarbonate (NaHCO3) ingestion on pVO2 kinetics, using a sufficient number of repeat-step transitions to provide high confidence in the results obtained.
Seven healthy males completed step tests to a work rate requiring 80% pVO2max on six separate occasions: three times after ingestion of 0.3 g x kg(-1) body mass NaHCO3 in 1 L of fluid, and three times after ingestion of a placebo (CON). Blood samples were taken to assess changes in acid-base balance, and pVO2 was measured breath-by-breath.
NaHCO3 ingestion significantly increased blood pH and [bicarbonate] both before and during exercise relative to the control condition (P < 0.001). The time constant of the phase II pVO2 response was not different between conditions (CON: 29 +/- 6 vs ALK: 32 +/- 7 s; P = 0.21). However, the onset of the pVO2 slow component was delayed by NaHCO3 ingestion (CON: 120 +/- 19 vs ALK: 147 +/- 34 s; P < 0.01), resulting in a significantly reduced end-exercise pVO2 (CON: 2.88 +/- 0.19 vs ALK: 2.79 +/- 0.23 L x min(-1); P < 0.05).
Metabolic alkalosis has no effect on phase II pVO2 kinetics but alters the pVO2 slow-component response, possibly as a result of the effects of NaHCO3 ingestion on muscle pH.
代谢性碱中毒（ALK）对高强度循环运动期间肺氧摄取（pVO2）动力学的影响存在争议。本研究的目的是通过摄入碳酸氢钠（NaHCO3）诱导代谢性碱中毒，使用足够数量的重复阶梯过渡来获得对结果的高度信心，以检验其对pVO2动力学的影响。
7名健康男性在六个不同场合完成了达到80% pVO2max工作强度的阶梯测试：三次是在摄入1 L液体中0.3 g/kg体重的NaHCO3后，三次是在摄入安慰剂（CON）后。采集血样以评估酸碱平衡变化，并逐次呼吸测量pVO2。
与对照条件相比，摄入NaHCO3后运动前和运动期间血液pH值和[碳酸氢盐]均显著升高（P < 0.001）。不同条件下II期pVO2反应的时间常数无差异（CON：29 ± 6 vs ALK：32 ± 7秒；P = 0.21）。然而，摄入NaHCO3使pVO2慢成分的起始延迟（CON：120 ± 19 vs ALK：147 ± 34秒；P < 0.01），导致运动结束时pVO2显著降低（CON：2.88 ± 0.19 vs ALK：2.79 ± 0.23 L·min-1；P < 0.05）。
代谢性碱中毒对II期pVO2动力学无影响，但改变了pVO2慢成分反应，这可能是由于摄入NaHCO3对肌肉pH值的影响所致。
