Abstract
PurposeEnteric-coated sodium bicarbonate (NaHCO3) can attenuate gastrointestinal (GI) symptoms following acute bicarbonate loading, although the subsequent effects on exercise performance have not been investigated. The purpose of this study was to examine the effects of enteric-coated NaHCO3 supplementation on high-intensity exercise performance and GI symptoms.MethodsEleven trained male cyclists completed three 4 km time trials after consuming; a placebo or 0.3 g∙kg–1 body mass NaHCO3 in enteric-coated or gelatin capsules. Exercise trials were timed with individual peak blood bicarbonate ion concentration ([HCO3–]). Blood acid–base balance was measured pre-ingestion, pre-exercise, and post-exercise, whereas GI symptoms were recorded pre-ingestion and immediately pre-exercise.ResultsPre-exercise blood [HCO3−] and potential hydrogen (pH) were greater for both NaHCO3 conditions (P < 0.0005) when compared to placebo. Performance time was faster with enteric-coated (− 8.5 ± 9.6 s, P = 0.044) and gelatin (− 9.6 ± 7.2 s, P = 0.004) NaHCO3 compared to placebo, with no significant difference between conditions (mean difference = 1.1 ± 5.3 s, P = 1.000). Physiological responses were similar between conditions, although blood lactate ion concentration was higher with gelatin NaHCO3 (2.4 ± 1.7 mmol∙L–1, P = 0.003) compared with placebo. Furthermore, fewer participants experienced GI symptoms with enteric-coated (n = 3) compared to gelatin (n = 7) NaHCO3.DiscussionAcute enteric-coated NaHCO3 consumption mitigates GI symptoms at the onset of exercise and improves subsequent 4 km cycling TT performance. Athletes who experience GI side-effects after acute bicarbonate loading may, therefore, benefit from enteric-coated NaHCO3 supplementation prior to exercise performance.
Highlights
High-intensity exercise bouts are impaired by peripheral fatigue (Thomas et al 2015), typically as a result of disturbances to intramuscular homeostasis (Jones et al 2008)
Inducing metabolic alkalosis prior to exercise, which can be achieved by oral ingestion of sodium bicarbonate (NaHCO3), has been shown to improve various performance measures during single bouts of high-intensity exercise (Matson and Tran 1993; Peart et al 2012; Lancha Junior et al 2015)
While some studies have shown that NaHCO3 can improve exercise performance despite GI distress (Price and Simons 2010), there is evidence to suggest that symptoms may compromise the performance-enhancing effects of supplementation (Cameron et al 2010; Saunders et al 2014; Deb et al 2018)
Summary
High-intensity exercise bouts are impaired by peripheral fatigue (Thomas et al 2015), typically as a result of disturbances to intramuscular homeostasis (Jones et al 2008). Significant decreases in muscle and blood potential hydrogen (pH) have been reported (Hollidge-Horvat et al 2000) as a result of the glycolytic contribution during high-intensity exercise (Baker et al 2010; Gastin 2001). Through increases in extracellular bicarbonate ion concentration ([HCO3–]), NaHCO3 supplementation can augment buffering capacity (Siegler et al 2010) and strong ion handling (Raymer et al 2004), both of which favour high-intensity exercise performance. While some studies have shown that NaHCO3 can improve exercise performance despite GI distress (Price and Simons 2010), there is evidence to suggest that symptoms may compromise the performance-enhancing effects of supplementation (Cameron et al 2010; Saunders et al 2014; Deb et al 2018). There is evidence to suggest that athletes may be deterred from supplementing with NaHCO3 due to the risk of GI symptoms during training and/or competition (Heibel et al 2018)
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