The impact of 48 h high carbohydratste 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-, and 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 +/- 1.8 g kg day(-1)) diet on two separate occasions, composed of high (54.8 +/- 10.5 g day(-1)) and low FODMAP (3.0 +/- 0.2 g day(-1)) content. Thereafter, participants completed a 2 h steady-state running exercise at 60% of VO2max(22.9 +/- 1.2 degrees C, 46.4 +/- 7.9% RH), followed by a 1 h distance performance test. Pre-exercise and every 20 min during steady-state exercise, 100 mL maltodextrin (10% w/v) solution was consumed. A 150 mL lactulose (20 g) 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 (H-2) 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 high carbohydrate low FODMAP (HC-LFOD) versus high carbohydrate high FODMAP (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 versus 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.