Gut-training: The impact of two weeks repetitive gut-challenge during exercise on gastrointestinal status, glucose availability, fuel kinetics, and running performance.
Ricardo J.S. Costa Physiologie appliquée, nutrition et métabolisme Publié sur le Web 19 January 2017.
Background: Due to gastrointestinal tract adaptability, the study aimed to determine the impact of two weeks gut-training protocol over two weeks on gastrointestinal status, blood glucose availability, fuel kinetics, and running performance.
Methods: Endurance runners (n= 25) performed a gut-challenge trial (GC1), comprising of 2 h running exercise at 60% VO2max whilst consuming gel-discs containing 30 g carbohydrates (2:1 glucose-fructose, 10% w/v) every 20 min, and a 1 h distance test. Participants were then randomly assigned to a carbohydrate gel-disc (CHO-S), carbohydrate food (CHO-F), or placebo (PLA) gut-training group for a two weeks repetitive gut-challenge intervention. Participants then repeated a second gut-challenge trial (GC2).
Results: Gastrointestinal symptoms reduced in GC2 on CHO-S (60%; p= 0.008) and CHO-F (63%; p= 0.046); reductions were greater than PLA (p< 0.05). H2 peak was lower in GC2 on CHO-S (mean (CI): 6 (4-8) ppm) compared with CHO-F (9 (6-12) ppm) and PLA (12 (2-21) ppm) (trial*time: p< 0.001). Blood glucose concentration was higher in GC2 on CHO-S (7.2 (6.3-8.1) mMol·L-1) compared with CHO-F (6.1 (5.7-6.5) mMol·L-1) and PLA (6.2 (4.9-7.5) mMol·L-1) (trial*time: p= 0.015). No difference in oxidation rates, plasma I-FABP and cortisol concentrations were observed between groups and trials. Distance test improved on CHO-S (5.2%) and CHO-F (4.3%) in GC2, but not on PLA (-2.1%) (trial*time: p= 0.009).
Conclusion: Two weeks of gut-training with CHO-S and CHO-F improved gastrointestinal symptoms and running performance compared with PLA. CHO-S also reduced malabsorption and increased blood glucose availability during endurance running compared with PLA.