Nutritional Intake and Gastrointestinal Problems during Competitive Endurance Events

PFEIFFER, B., T. STELLINGWERFF, A. B. HODGSON, R. RANDELL, K. POTTGEN, P. RES, and A. E. JEUKENDRUP. Nutritional Intake and Gastrointestinal Problems during Competitive Endurance Events. Med. Sci. Sports Exerc., Vol. 44, No. 2, pp. 344-351, 2012. There is little information about the actual nutrition and fluid intake habits and gastrointestinal (GI) symptoms of athletes during endurance events. Purpose: This study aimed to quantify and characterize energy, nutrient, and fluid intakes during endurance competitions and investigate associations with GI symptoms. Method: A total of 221 endurance athletes (male and female) were recruited from two Ironman triathlons (IM Hawaii and IM GER), a half-Ironman (IM 70.3), a MARATHON, a 100/150-km CYCLE race. Professional cyclists (PRO) were investigated during stage racing. A standardized postrace questionnaire quantified nutrient intake and assessed 12 GI symptoms on a scale from 0 (no problem) to 9 (worst it has ever been) in each competition. Results: Mean CHO intake rates were not significantly different between IM Hawaii, IM GER, and IM 70.3 (62 +/- 26, 71 +/- 25, and 65 +/- 25 g.h(-1), respectively), but lower mean CHO intake rates were reported during CYCLE (53 +/- 22 g.h(-1), P = 0.044) and MARATHON (35 +/- 26 g.h(-1), P < 0.01). Prevalence of serious GI symptoms was highest during the IM races (similar to 31%, P = 0.001) compared with IM 70.3 (14%), CYCLE (4%), MARATHON (4%), and PRO (7%) and correlated to a history of GI problems. In all data sets, scores for upper and lower GI symptoms correlated with a reported history of GI distress (r = 0.37 and r = 0.51, respectively, P G 0.001). Total CHO intake rates were positively correlated with nausea and flatulence but were negatively correlated with finishing time during both IM (r = -0.55 and r = -0.48, P < 0.001). Conclusions: The present study demonstrates that CHO intake rates vary greatly between events and individual athletes (6-136 g.h(-1)). High CHO intake during exercise was related not only to increased scores for nausea and flatulence but also to better performance during IM races.