Does oral buffered sodium supplementation reduce nausea and vomiting during an ultramarathon?

This work examines whether nausea or vomiting during an ultramarathon are due to a fluid or electrolyte imbalance, and if these symptoms can be reduced through the use of buffered sodium supplements. Starters (n = 376) of a 161.3-km ultramarathon underwent body weight measurements, 74.5% completed a post-race questionnaire, and 53.0% also underwent a post-race blood draw. The incidence of nausea or vomiting progressively increased during the race, and affected 60% of runners overall. Weight change and rate of sodium intake in supplements or in buffered sodium supplements did not differ between those with and without nausea or vomiting. Post-race serum sodium concentration also did not differ between those with and without symptoms in the last race segment. We conclude that weight change, the rate of sodium intake in supplements or in buffered sodium supplements, and serum sodium concentration are not related to symptoms of nausea or vomiting during a 161-km ultramarathon.