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

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Bibliographic Details
Title translated into German:Zweiwöchige repetitive Darmentleerung reduziert belastungsbedingte gastrointestinale Symptome und Malabsorption
Author:Miall, A.; Khoo, A.; Rauch, C.; Snipe, R.M.J.; Camões-Costa, V.L.; Gibson, P.R.; Costa, R.J.S.
Published in:Scandinavian journal of medicine & science in sports
Published:28 (2018), 2, S. 630-640, Lit.
Format: Publications (Database SPOLIT)
Publication Type: Journal article
Media type: Electronic resource (online) Print resource
ISSN:0905-7188, 1600-0838
Online Access:
Identification number:PU201803001736

Author's 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) 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.