Suplementação de bicarbonato de sódio e desempenho em exercício intermitentede alta intensidade: consistência dos efeitos e estratégias de otimização

Abstract

Sodium bicarbonate (SB) supplementation has been shown to be an effective nutritional strategy to improve performance during high-intensity exercise, although it is associated with various side-effects. Supplementation of high amounts of SB are required since some is lost in the stomach causing discomfort. Additionally, studies show large interindividual variation in the time to peak blood bicarbonate concentration (Tmax). SB supplementation could be an effective strategy to improve exercise performance in hypoxia, where muscle acidosis may be increased. This project had three objectives: Study A investigated the effect of SB supplementation in gastro-resistant capsules on blood pH and bicarbonate, and associated sideeffects, as well as the reproducibility of the blood bicarbonate response on three distinct occasions; Study B investigated the effect of SB supplementation in gastro-resistant tablets on blood pH and bicarbonate, and associated side-effects; and Study C investigated the effect of SB supplementation on exercise performance, blood variables and side-effects in conditions of normoxia and hypoxia. In Study A Part I, we analyzed the pharmacokinetics of blood pH and bicarbonate and side-effects for 4 h after supplementation of 0.1 and 0.3 g•kg -1 SB, comparing gastro-resistant and gelatine capsules. In part II, we assessed the consistency of these blood pharmacokinetic responses after 0.3 g•kg -1 SB on three separate occasions. In part III, we investigated the pharmacokinetic responses to SB supplementation in an individual who had undergone bariatric surgery. In Study B, we analysed the pharmacokinetics of blood pH and bicarbonate and side-effects for 6 h after supplementation of 0.1 and 0.3 g•kg -1 SB, comparing supplementation in solution, and gelatine and gastro-resistant tablets. In Study C we supplemented volunteers with placebo or 0.30 g•kg -1 SB and after 90 min measured performance during 3 bouts of the Wingate test in hypoxic and normoxic conditions, and sideeffects were also evaluated. The results showed that there were no differences in blood measures and side-effects between the types of capsules, only between doses (A -part I). Reproducibility was moderate at the group level and poor at the individual level, and Tmax was not reproducible across the three sessions. However, a window of ergogenic potential of ~3h was shown (A -part II). Increases in blood bicarbonate in an individual after bariatric surgery were higher than compared to normal individuals (A -part III). The increases in blood pH and bicarbonate were lower with supplementation of gastro-resistant tablets compared to gelatine capsules and solution, with no differences in side-effects (Study B). SB supplementation was ergogenic for performance only in normoxia, while hypoxia increased side-effects with supplementation (Study C). In conclusion, there was no advantage in supplementing SB using gastro-resistant capsules or tablets. Blood pharmacokinetics following supplementation are not reproducible at the intra-individual or inter-...