[Purpose] This study was performed to investigate the acid-base and ion balance at rest and after exercise in healthy males under normoxia, moderate hypoxia, and severe hypoxia.
[Methods] Ten healthy Korean males completed three different trials on di...
[Purpose] This study was performed to investigate the acid-base and ion balance at rest and after exercise in healthy males under normoxia, moderate hypoxia, and severe hypoxia.
[Methods] Ten healthy Korean males completed three different trials on different days, comprising exercise under normoxia (F<sub>i</sub>O<sub>2</sub> = 20.9%, N trial), moderate hypoxia (F<sub>i</sub>O<sub>2</sub> = 16.5%, MH trial), and severe hypoxia (F<sub>i</sub>O<sub>2</sub> = 12.8%, SH trial). They undertook endurance exercise for 30 min on a cycle ergometer at the same relative exercise intensity equivalent to 80% maximal heart rate under all conditions. Capillary blood samples were obtained to determine acid-base and ion balance at rest and after exercise.
[Results] Exercise-induced blood lactate elevations were significantly increased as hypoxic conditions became more severe; SH > MH > N trials (P = 0.003). After exercise, blood glucose levels were significantly higher in the SH trial than in the N and MH trials (P = 0.001). Capillary oxygen saturation (S<sub>C</sub>O<sub>2</sub>) levels were significantly lowered as hypoxic conditions became more severe; SH > MH > N trials (P < 0.001). The pH levels were significantly lower in the MH trial than that in the N trial (P = 0.010). Moreover, H<sub>C</sub>O<sub>3-</sub> levels were significantly lower in the SH trial than in the N trial, with significant interaction (P = 0.003). There were no significant differences in blood Na<sup>+</sup>, K<sup>+</sup>, and Ca<sup>2+</sup> levels between the trials.
[Conclusion] MH and SH trials induced greater differences in glucose, lactate, S<sub>C</sub>O<sub>2</sub>, pH, and HCO<sub>3-</sub> levels in capillary blood compared to the N trial. Additionally, lactate, S<sub>C</sub>O<sub>2</sub>, and HCO<sub>3-</sub> levels showed greater changes in the SH trial than in the MH trial. However, there were no significant differences in Na<sup>+</sup>, K<sup>+</sup>, and Ca<sup>2+</sup> levels in MH and SH trials compared to the N trial.
[Key words] acute hypoxia, metabolic stress, capillary