Published in:
01-01-2016 | Original Article
Effects of pre-exercise alkalosis on the decrease in \(\dot{V}O_{2}\) at the end of all-out exercise
Published in: European Journal of Applied Physiology | Issue 1/2016
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Purpose
This study determined the effects of pre-exercise sodium bicarbonate ingestion (ALK) on changes in oxygen uptake (\(\dot{V}O_{2}\)) at the end of a supramaximal exercise test (SXT).
Methods
Eleven well-trained cyclists completed a 70-s all-out cycling effort, in double-blind trials, after oral ingestion of either 0.3 g kg−1 of sodium bicarbonate (NaHCO3) or 0.2 g kg−1 body mass of calcium carbonate (PLA). Blood samples were taken to assess changes in acid–base balance before the start of the supramaximal exercise, and 0, 5 and 8 min after the exercise; ventilatory parameters were also measured at rest and during the SXT.
Results
At the end of the PLA trial, which induced mild acidosis (blood pH = 7.20), subjects presented a significant decrease in \(\dot{V}O_{2}\) (P < 0.05), which was related to the amplitude of the decrease in minute ventilation (\(\dot{V}_{E}\)) during the SXT (r = 0.70, P < 0.01, n = 11). Pre-exercise metabolic alkalosis significantly prevented the exercise-induced decrease in \(\dot{V}O_{2}\) in eleven well-trained participants (PLA: 12.5 ± 2.1 % and ALK: 4.9 ± 0.9 %, P < 0.05) and the decrease in mean power output was significantly less pronounced in ALK (P < 0.05). Changes in the \(\dot{V}O_{2}\) decrease between PLA and ALK trials were positively related to changes in the \(\dot{V}_{E}\) decrease (r = 0.74, P < 0.001), but not to changes in power output (P > 0.05).
Conclusions
Pre-exercise alkalosis counteracted the \(\dot{V}O_{2}\) decrease related to mild acidosis, potentially as a result of changes in \(\dot{V}_{E}\) and in muscle acid–base status during the all-out supramaximal exercise.