Association of gastrointestinal distress in ultramarathoners with race diet

Gastrointestinal (GI) distress is common during ultrarunning.

To determine if race diet is related to GI distress in a 161-km ultramarathon.

Fifteen (10 male, 5 female) consenting runners in the Javelina Jundred (6.5 loops on a desert trail) participated. Body mass was measured immediately prerace and after each loop. Runners reported if they had nausea, vomiting, abdominal cramps, and/or diarrhea after each loop. Subjects were interviewed after each loop to record food, fluid, and electrolyte consumption. Race diets were analyzed using Nutritionist Pro.

Nine (8 male, 1 female) of 15 runners experienced GI distress including nausea (89%), abdominal cramps (44%), diarrhea (44%), and vomiting (22%). Fluid consumption rate was higher (p = .001) in runners without GI distress (10.9 ± 3.2 ml · kg-1 · hr-1) than in those with GI distress (5.9 ± 1.6 ml · kg-1 · hr-1). Runners without GI distress consumed a higher percentage fat (p = .03) than runners with GI distress (16.5 ± 2.6 vs. 11.1 ± 5.0). In addition, fat intake rate was higher (p = .01) in runners without GI distress (0.06 ± 0.03 g · kg-1 · hr-1) than in runners with GI distress (0.03 ± 0.01 g · kg-1 ·hr-1). Lower fluid and fat intake rates were evident in those developing GI distress before the onset of symptoms.

A race diet with higher percentage fat and higher intake rates of fat and fluid may protect ultramarathoners from GI distress. However, these associations do not indicate cause and effect, and factors other than race diet may have contributed to GI distress.