Acute sodium bicarbonate loading has negligible effects on resting and exercise blood pressure but causes gastrointestinal distress

Abstract

Oral ingestion of sodium bicarbonate (bicarbonate loading) has acute ergogenic effects on short-duration, high-intensity exercise. Because sodium bicarbonate is 27% sodium, ergogenic doses (i.e. 300 mg·kg−1) result in sodium intakes well above the Dietary Reference Intakes upper limit of 2300 mg/day. Therefore, it is conceivable that bicarbonate loading could have hypertensive effects. Therefore, we performed a double-blind cross-over trial to evaluate the hypothesis that bicarbonate loading increases resting and exercise blood pressure (BP). A secondary hypothesis was that bicarbonate loading causes gastrointestinal distress. Eleven endurance-trained men and women (exercise frequency, 4.6±0.4 sessions/wk; duration, 65±6 min/session) underwent testing on two occasions in random sequence: once after bicarbonate loading (300 mg·kg−1) and once after placebo ingestion. BP and heart rate (HR) were measured before bicarbonate or placebo consumption, 30 minutes after consumption, during 20 min of steady state submaximal cycling exercise, and during recovery. Bicarbonate loading did not affect systolic BP during rest, exercise, or recovery (p=0.38 for main treatment effect). However, it resulted in modestly higher diastolic BP (main treatment effect, +3.3±1.1 mmHg, p=0.01) and higher HR (main treatment effect, +10.1±2.4 bpm, p=0.002). Global ratings of gastrointestinal distress severity (0–10 scale) were greater after bicarbonate ingestion (5.1±0.5 vs. 0.5±0.2, p<0.0001). Furthermore, 10 of the 11 subjects (91%) experienced diarrhea, 64% experience bloating and thirst, and 45% experienced nausea after bicarbonate loading. In conclusion, although a single, ergogenic dose of sodium bicarbonate does not appear to have acute, clinically important effects on resting or exercise BP, it does cause substantial GI distress.

Effects of daily ingestion of sodium bicarbonate on acid-base status and anaerobic performance during an altitude sojourn at high altitude: a randomized controlled trial

“…PTSR performance parameters in this study might also have been influenced by gastro-intestinal (GI) disturbances. Negative GI symptoms caused by bicarbonate ingestion have been reported in the literature [21,72,73] and GI discomfort is suggested to have ergolytic effects on anaerobic performance [15,19]. Unfortunately, we did not carry out any structured monitoring of GI discomfort in the current participants, which represents a limitation of this study.…”

Dose-Response of Sodium Bicarbonate Ingestion Highlights Individuality in Time Course of Blood Analyte Responses

“…In these situations it would also be advisable to consume 0.1 g . kg -1 BM of NaHCO3, given that lower doses reduce the intensity and/or frequency of negative GI symptoms (McNaughton, 1992;Kahle et al 2013), which would benefit athletes in the competitive setting. Some athletes require co-ingestion of NaHCO3 with food and fluid in order to reduce GI symptoms, therefore lowering the dose could lead to a reduction in the amount of food/fluid ingested, vital for athletes competing numerous times within a short period.…”

“…NaHCO3 ingestion can result in gastrointestinal (GI) distress Siegler et al 2012;Peart et al 2012), with 10% of participants not tolerating the doses needed to gain a beneficial performance effect (McNaughton et al 2008). As dose increases, GI discomfort is more commonplace, often without additional performance improvements (McNaughton, 1991;Kahle et al 2013). To combat GI symptoms, stacking dose strategies has been implemented (Sale et al 2011;Saunders et al 2014a); splitting larger doses (0.3 g .…”

Ayudas ergogénicas en el deporte

“…No obstante, un estudio de Kahle y cols. (41) no encontró ninguna relación, aunque se llevó a cabo en jóvenes, menos sensibles a la ingesta de sal.…”