Changes in acid–base and ion balance during exercise in normoxia and normobaric hypoxia

Abstract

PurposeBoth exercise and hypoxia cause complex changes in acid–base homeostasis. The aim of the present study was to investigate whether during intense physical exercise in normoxia and hypoxia, the modified physicochemical approach offers a better understanding of the changes in acid–base homeostasis than the traditional Henderson–Hasselbalch approach.MethodsIn this prospective, randomized, crossover trial, 19 healthy males completed an exercise test until voluntary fatigue on a bicycle ergometer on two different study days, once during normoxia and once during normobaric hypoxia (12% oxygen, equivalent to an altitude of 4500 m). Arterial blood gases were sampled during and after the exercise test and analysed according to the modified physicochemical and Henderson–Hasselbalch approach, respectively.ResultsPeak power output decreased from 287 ± 9 Watts in normoxia to 213 ± 6 Watts in hypoxia (−26%, P < 0.001). Exercise decreased arterial pH to 7.21 ± 0.01 and 7.27 ± 0.02 (P < 0.001) during normoxia and hypoxia, respectively, and increased plasma lactate to 16.8 ± 0.8 and 17.5 ± 0.9 mmol/l (P < 0.001). While the Henderson–Hasselbalch approach identified lactate as main factor responsible for the non-respiratory acidosis, the modified physicochemical approach additionally identified strong ions (i.e. plasma electrolytes, organic acid ions) and non-volatile weak acids (i.e. albumin, phosphate ion species) as important contributors.ConclusionsThe Henderson–Hasselbalch approach might serve as basis for screening acid–base disturbances, but the modified physicochemical approach offers more detailed insights into the complex changes in acid–base status during exercise in normoxia and hypoxia, respectively.Electronic supplementary materialThe online version of this article (doi:10.1007/s00421-017-3712-z) contains supplementary material, which is available to authorized users.

Factors Related to Cardiac Troponin T Increase after Participation in a 100 Km Ultra-Marathon

“…However, periods of anaerobic metabolism during the race may lead to an increase in lactate concentration [18,19]. We postulate that periodic changes in lactate concentration may reflect systemic changes in acid-base and electrolytic balance as described in other studies [18][19][20][21]. As shown by our and other research studies, ultra-endurance exercise promotes inflammatory reaction measured in our study by the change of hs-CRP concentration [4,7].…”

“…Long-lasting endurance event is usually performed around (or even below) first ventilator threshold. However, periods of anaerobic metabolism during the race may lead to an increase in lactate concentration [18,19]. We postulate that periodic changes in lactate concentration may reflect systemic changes in acid-base and electrolytic balance as described in other studies [18][19][20][21].…”

“…Runners with significant hs-TnT increase after the race had more L peaks > 2 mmol/L during the race (median 7 IQR 4-8 vs. 3.5 IQR 2-5, p = 0.04). In consequence, those with mean L concentration during the race above the median of 2.1 mmol/L had a significantly higher increase of hs-TnT (15)(16)(17)(18)(19) vs. 8 IQR 7-12 vs. ng/L, p = 0.02) as demonstrated on Figure 3. Mean L concentration during the race correlated with change in hs-TnT (rho = 0.52, p = 0.03).…”

Effects of 2-Week Exercise Training in Hypobaric Hypoxic Conditions on Exercise Performance and Immune Function in Korean National Cycling Athletes with Disabilities: A Case Report

“…Generally, exercise performance enhancement is influenced by several factors, including the nervous system, hormones, and various proteins, that significantly control the muscle tissue, resulting in efficient oxygen and energy utilization and hematological factors, such as improved oxygen-transporting capacity in the blood [21]. Additionally, the non-hematological factors include increased oxidative enzyme activity [22,23], increased amount and density of the mitochondria [24][25][26][27], increased energy-utilizing capacity and changes in substrate utilization [9,28,29], enhanced blood lactate level tolerance and acid-base balance in the muscles [4,30], improved blood rheological and hemodynamic functions [10,31], enhanced intracellular iron delivery capacity [32], increased autonomic nervous system balance [33,34], changes in various hormone secretions [9,35], and increases in various proteins associated with oxygen utilization [36,37]. The physiological changes in the abovementioned non-hematological factors had positive effects on the 3-km time trial records after our 2-week exercise training in hypobaric hypoxic conditions.…”

The effects of sodium bicarbonate ingestion on cycling performance and acid base balance recovery in acute normobaric hypoxia

“…This includes an exacerbated impairment of calcium ion (Ca 2+ ) release from the sarcoplasmic reticulum (SR) (Duhamel et al, 2004), more rapid accumulation of energy metabolites (i.e. hydrogen ions (H + ) and inorganic phosphate (Pi)) (Adam and Welch, 1980;Hogan et al, 1999), and greater decrements in the strong ion difference (SID) compared to the equivalent normoxic exercise (Lühker et al, 2017). All of these factors are implicated as the source of fatigue during high-intensity exercise (Allen et al, 2008;Cairns and Lindinger, 2008).…”