The impact of 48-h high carbohydrate diets with high and low FODMAP content on gastrointestinal status and symptoms in response to endurance exercise, and subsequent endurance performance.

This study investigated the effects of a high carbohydrate diet, with varied fermentable oligo- di- mono- saccharide and polyol (FODMAP) content, before endurance exercise on gastrointestinal integrity, motility, and symptoms; and subsequent exercise performance. Twelve endurance athletes were provided with a 48-h high carbohydrate (mean±SD: 12.1±1.8g·kgˑday-1) diet on two separate occasions, composed of high (54.8±10.5g·day-1) and low FODMAP (3.0±0.2g·day-1) content. Thereafter, participants completed a 2-h steady-state running exercise at 60% of VO2max (22.9±1.2°C, 46.4±7.9% RH), followed by a 1-h distance performance test. Pre-exercise and every 20-min during steady-state exercise, 100mL maltodextrin (10% w/v) solution was consumed. A 150mL lactulose (20g) solution was consumed 30-min into the distance performance test to determine orocecal transit time (OCTT) during exercise. Blood was collected pre- and post-exercise to determine gastrointestinal integrity biomarkers (i.e., I-FABP, sCD14, and CRP). Breath hydrogen (H2) and gastrointestinal symptoms (GIS) were determined pre-exercise, every 15-min during, and throughout recovery. No differences in gastrointestinal integrity biomarkers, OCTT, or distance completed were observed between trials. Pre-exercise total-GIS (1.3±2.9 vs. 4.3±4.4), gut discomfort (9.9±8.1 vs. 15.8±9.0) and upper-GIS (2.8±2.6 vs. 5.7±4.8) during exercise were less severe on HC-LFOD vs. HC-HFOD (p<0.05). Gut discomfort (3.4±4.4 vs. 0.2±0.6) and total-GIS (4.9±6.8 vs. 0.2±0.6) were higher during recovery on HC-LFOD vs. HC-HFOD (p<0.05). The FODMAP content of a 48-h high carbohydrate diet does not impact gastrointestinal integrity or motility in response to endurance exercise. However, a high FODMAP content exacerbates GIS before and during exercise, but this does not impact performance outcomes.