Blood Chemistry, Acid-Base, Electrolyte, Blood Lactate Metabolism and Sleep at 3480 m in Mountain Marathon Runners

Abstract

Altered blood chemistry, acid-base and electrolyte are suggested determinants of sleep disturbance, with frequent arousal at high altitude even in well and long-trained altitude marathon runners. In this sample of experienced altitude marathon runners with maximal aerobic power at sea level of 61.4 ± 2.7 ml/kg −1 ·min −1 we found that pO 2 and percent of oxygen saturation (%SO 2 ) were lower at 2050 m and 3480 m than at sea level; pO 2 was higher after 38 -41 hours than after 30 -31 hours of acclimatization at 3480 m (P < 0.05). After ascentto 3480 m %SO 2 decreased (P < 0.003). Compared to sea level values, pH increased at high altitude (P < 0.05) consistent with changes in pCO 2 and (P < 0.05). Nocturnal %SpaO 2 at a sleeping altitude of 3480 m was lower (P < 0.05) than at sea level. At high altitude, the percent of wake (W) time and delay falling asleep (DFA) increased, whereas non-rapid eye movement sleep (N-REM), REM sleep and total sleep time (TST) decreased (P < 0.05). Simple regression analysis disclosed a significant correlation between the changes in TST and the percent of REM sleep and the changes in %SpaO 2 recorded during sleep (P < 0.05). Simple regression analysis showed a positive correlation between the changes in pO 2 at higher altitude and the percent of W and of TST (P < 0.05). The changes in pO 2 , tCO 2 and . Simple regression analysis demonstrated that the changes in pH at high altitude correlated positively and significantly with the percent of W and the DFA and negatively with the percent of changes in NREM sleep, REM sleep, NREM + REM sleep (P < 0.05). The decrease in the TST at high altitude correlated significantly and negatively with the changes in pCO 2 , tCO 2 , and [K + ] (P < 0.05). Our data demonstrate that the arterialized ear lobe techniques we used for evaluating most of the changes in blood chemistry, acid-base, electrolyte and blood lactate metabolism aresuitable for clinical and laboratory assessment and are important predictors of the quality and quantity of acclimatization and sleep at high altitude.