Dietary restrictions in endurance runners to mitigate exercise-induced gastrointestinal symptoms

Endurance runners frequently experience exercise-induced gastrointestinal (GI) symptoms, negatively impacting their performance. Food choices pre-exercise have a significant impact on the gut's tolerance to running, yet little information is available as to which foods runners restrict prior to exercise.

A questionnaire designed to assess dietary restrictions pre-racing and gastrointestinal symptoms was administered to 388 runners. Fisher's exact tests determined differences in gender, age, performance level, and distance with follow-up multivariable logistic regression modeling.

Runners regularly avoided meat (32%), milk products (31%), fish/seafood (28%), poultry (24%), and high-fiber foods (23%). Caffeinated beverages were commonly avoided in events 10 km or less (p < .001); whereas in females, increased running distance was a predictor of avoiding high-fiber foods (OR = 6.7; 95% CI = 1.6-28.5). Rates of food avoidance were elevated in younger and more competitive runners. Common GI symptoms included stomach pain/cramps (42%), intestinal pain/discomfort (23%), side ache/stitch (22%), urge to defecate (22%), and bloating (20%). The prevalence of GI symptoms was higher in younger athletes, especially females, which may explain their propensity to avoid foods. Lower recreational athletes were the least likely to report GI symptoms. Diarrhea incidence increased with running distance.

Identification of voluntary food restrictions in the pre-running meal highlights trends that can direct further research.