Two weeks of repetitive gut-challenge reduce exercise-associated gastrointestinal symptoms and malabsorption

A. Miall, A. Khoo, C. Rauch, R. M. J. Snipe, V. L. Camões-Costa, P. R. Gibson, R. J. S. Costa

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16 Citations (Scopus)

Abstract

Debilitating gastrointestinal symptoms is a common feature of endurance running and may be exacerbated by and/or limit the ability to tolerate carbohydrate intake during exercise. The study aimed to determine whether two weeks of repetitive gut-challenge during running can reduce exercise-associated gastrointestinal symptoms and carbohydrate malabsorption. Endurance runners (n=18) performed an initial gut-challenge trial (GC1) comprising 2-hour running exercise at 60% VO2max (steady state) while consuming a formulated gel-disk containing 30 g carbohydrates (2:1 glucose-fructose, 10% w/v) every 20 minutes, followed by a 1-hour running effort bout. Gastrointestinal symptoms, feeding tolerance, and breath hydrogen (H2) were determined along the gut-challenge trial. After GC1, participants were randomly assigned to a blinded carbohydrate (CHO, 90 gCHO hour-1) or placebo (PLA, 0 gCHO hour-1) gut-training group. This comprised of consuming the group-specific feeding intervention during 1-hour running exercise at 60% VO2max equivalent, daily over a period of two weeks. Participants then repeated the gut-challenge trial (GC2). In GC2, a reduced gut discomfort (P=.012), total (P=.009), upper- (P=.015), and lower-gastrointestinal (P=.008) symptoms, and nausea (P=.05) were observed on CHO, but not PLA. Feeding tolerance did not differ between GC1 and GC2 on CHO and PLA. H2 peak was attenuated in GC2 (6±3 ppm) compared to GC1 (13±6 ppm) on CHO (P=.004), but not on PLA (GC1 11±7 ppm, and GC2 10±10 ppm). The effort bout distance was greater in GC2 (12.3±1.3 km) compared with GC1 (11.7±1.5 km) on CHO (P=.035) only. Two weeks of repetitive gut-challenge improve gastrointestinal symptoms and reduce carbohydrate malabsorption during endurance running, which may have performance implications.

Original languageEnglish
Pages (from-to)630-640
Number of pages11
JournalScandinavian Journal of Medicine & Science in Sports
Volume28
Issue number2
DOIs
Publication statusPublished - Feb 2018

Keywords

  • Breath hydrogen
  • Discomfort
  • Endurance
  • Fructose
  • Glucose
  • Gut training
  • Running

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