Common questions and misconceptions of sodium bicarbonate as an ergogenic aid: what does the science really show?

Sodium bicarbonate is an ergogenic extracellular buffering agent that has recently garnered more interest because novel formulations purported to mitigate gastrointestinal symptoms, thereby increasing use with high-profile athletes. The effects of sodium bicarbonate on various aspects of exercise performance have been explored in hundreds of scientific articles. However, questions persist about aspects of its effectiveness and the potential side effects associated with the extracellular buffer. In this review, we provide answers to several questions related to sodium bicarbonate supplementation. These questions covered include: (1) What are sodium bicarbonate's proposed mechanisms for enhancing performance? (2) Does sodium bicarbonate cause gastrointestinal symptoms, and why? (3) What are the different ways in which sodium bicarbonate can be ingested, and how does this affect blood bicarbonate changes and exercise performance? (4) How does sodium bicarbonate affect performance in short-duration exercise (≤10 min)? (5) How does sodium bicarbonate affect performance in long-duration exercise, and should it be used before and during such events? (6) Is there a potential rationale for sodium bicarbonate use at altitude? (7) Is it worth ingesting sodium bicarbonate for exercise in the heat? (8) When is the best time to take sodium bicarbonate before exercise? When does blood bicarbonate peak in the blood? (9) What happens when sodium bicarbonate is taken after exercise instead of before? (10) Should sodium bicarbonate be taken throughout training, or can it be taken just during the day of a competition/game/race? Are there benefits of taking sodium bicarbonate for training adaptations? (11) Which sports mainly benefit from sodium bicarbonate supplementation? (12) Should one worry about the sodium dose? (13) How does extracellular buffering compare to intracellular buffering agents such as beta-alanine? (14) Is there a possible placebo effect with sodium bicarbonate? (15) Are the ergogenic effects of sodium bicarbonate sex-specific? To address these questions, we conducted an evidence-based review of the literature on sodium bicarbonate supplementation, with contributions from several invited experts. Comprehensive answers are provided alongside suggestions for future research.