• Delay fatigue during high-intensity efforts. See the fasted-training study.
  
  
• Buffer acid build-up and increase total reps before exhaustion. See the CrossFit study.
  
  
• Improve repeated sprint power, even in heat. See the heat chamber study.
  
  
• Improve time-trial performance over longer efforts. See the 40km cycling study.

However, baking soda causes GI distress in roughly 1 in 3 athletes.

In trained men, a 14-hour fast alone improved sprint power by roughly 10% and muscular endurance by 24%. Adding sodium bicarbonate on top pushed sprint power up ~21% and cut fatigue by 37%, though it did cause mild stomach discomfort in some athletes.

In highly trained female CrossFit athletes, sodium bicarbonate increased both time to exhaustion and total reps during cycling intervals and a barbell thruster test. It also caused more stomach upset in some athletes than the alternative.

Trained cyclists improved a 40km time trial by an average of 54 seconds when bicarbonate was delivered as mini-tablets inside a carbohydrate hydrogel, which is a delivery method built specifically to minimize the usual stomach issues.

Across a meta-analysis of 11 placebo-controlled running trials, gastrointestinal side effects showed up in roughly 30% of bicarbonate trials versus about 3% on placebo, and close to 1 in 11 people couldn't tolerate it at all.