Sodium bicarbonate ingestion mitigates the heat-induced hyperventilation and reduction in cerebral blood velocity during exercise in the heat
Sodium bicarbonate ingestion mitigates the heat-induced hyperventilation and reduction in cerebral blood velocity during exercise in the heat
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DOI：
10.1152/japplphysiol.00261.2021
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发表时间：
2021-11-01
影响因子：
3.3
通讯作者：
Tsuji, Bun
中科院分区：
文献类型：
--
作者：
Katagiri, Akira;Kitadai, Yasuhiko;Tsuji, Bun
在高温下运动时的体温过高会导致每分钟通气量（_VE）增加，从而导致动脉CO2分压（PaCO 2）和脑血流量降低。另一方面，据报道，碳酸氢钠的摄入导致代谢紊乱，导致在热中性环境中长时间运动期间_VE降低和PaCO 2升高。在此，我们研究了在高温下长时间运动时，碳酸氢钠的摄入是否能抑制热诱导的换气过度以及由此产生的低碳酸血症和脑灌注不足。11名健康男性摄入碳酸氢钠溶液（0.3 g/kg体重）（NaHCO 3试验）或氯化钠溶液（0.208 g/kg）（NaCl试验）。摄入90分钟后，受试者在高温（35摄氏度和40%相对湿度）下以50%的峰值摄氧量进行60分钟的循环运动。食管温度在整个试验期间没有差异（P = 0.56，试验的主要效应）。在NaCl试验中，随着运动时间的延长，_VE逐渐增加，但在NaHCO 3试验中，_VE的增加被减弱（P = 0.01，试验的主效应）。相应地，NaHCO 3试验中估计的PaCO 2和大脑中动脉血流速度（前脑血流指数）高于NaCl试验（P = 0.002和0.04，试验的主要效应）。在NaHCO 3中，自感劳累的评分低于NaCl试验（P = 0.02，试验的主效应）。这些结果表明，碳酸氢钠的摄入减轻了热诱导的过度通气和减少PaCO 2和脑血流速度在长时间的运动在热。新&值得注意的是，高温会导致换气过度，并伴随着低碳酸血症和脑灌注不足。脑灌注不足可能是中枢疲劳的基础。我们证明，碳酸氢钠摄入减少热诱导的过度通气，并在高温下长时间运动时减弱低碳酸血症相关的脑灌注不足。此外，我们表明，碳酸氢钠的摄入量降低了运动过程中的主观用力评分。这项研究提供了新的见解，有效的战略，防止中枢疲劳的发展过程中，在炎热的运动。
Hyperthermia during exercise in the heat causes minute ventilation ( _VE) to increase, which leads to reductions in arterial CO2 partial pressure (PaCO2) and cerebral blood flow. On the other hand, sodium bicarbonate ingestion reportedly results in metabolic alkalosis, leading to decreased _VE and increased PaCO2 during prolonged exercise in a thermoneutral environment. Here, we investigated whether sodium bicarbonate ingestion suppresses heat-induced hyperventilation and the resultant hypocapnia and cerebral hypoperfusion during prolonged exercise in the heat. Eleven healthy men ingested a solution of sodium bicarbonate (0.3 g/kg body wt) (NaHCO3 trial) or sodium chloride (0.208 g/kg) (NaCl trial). Ninety minutes after the ingestion, the subjects performed a cycle exercise for 60 min at 50% of peak oxygen uptake in the heat (35 degrees C and 40% relative humidity). Esophageal temperature did not differ between the trials throughout (P = 0.56, main effect of trial). _VE gradually increased with exercise duration in the NaCl trial, but the increases in _VE were attenuated in the NaHCO3 trial (P = 0.01, main effect of trial). Correspondingly, estimated PaCO2 and middle cerebral artery blood velocity (an index of anterior cerebral blood flow) were higher in the NaHCO3 than the NaCl trial (P = 0.002 and 0.04, main effects of trial). Ratings of perceived exertion were lower in the NaHCO3 than the NaCl trial (P = 0.02, main effect of trial). These results indicate that sodium bicarbonate ingestion mitigates heat-induced hyperventilation and reductions in PaCO2 and cerebral blood velocity during prolonged exercise in the heat. NEW & NOTEWORTHY Hyperthermia causes hyperventilation and concomitant hypocapnia and cerebral hypoperfusion. The cerebral hypoperfusion may underlie central fatigue. We demonstrate that sodium bicarbonate ingestion reduces heat-induced hyperventilation and attenuates hypocapnia-related cerebral hypoperfusion during prolonged exercise in the heat. In addition, we show that sodium bicarbonate ingestion reduces ratings of perceived exertion during the exercise. This study provides new insight into the development of effective strategies for preventing central fatigue during exercise in the heat.