The influence of exercise intensity and exercise mode on gastrointestinal damage

• Published in: Applied physiology, nutrition, and metabolism nutrition, and metabolism, 2021-09, Vol.46 (9), p.1105-1110
• Main Authors: Edwards, Kate H, Ahuja, Kiran D, Watson, Greig, Dowling, Courtney, Musgrave, Harrison, Reyes, Jessica, Cherry, James, Kitic, Cecilia M
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Anaerobic Threshold; Bicycling; Bicycling - physiology; Clinical trials; course à pied; Cross-Over Studies; cycling; cyclisme; Digestive system; Exercise; Exercise - physiology; Exercise intensity; Fatty Acid-Binding Proteins - blood; Female; Gastrointestinal diseases; Gastrointestinal Diseases - etiology; Gastrointestinal Diseases - physiopathology; gastrointestinal symptoms; Gastrointestinal Tract - physiopathology; Health aspects; Heart Rate; Humans; I-FABP; Injuries; intestinal permeability; Male; Maximum oxygen consumption; Methods; Oxygen Consumption; Perception - physiology; perméabilité intestinale; Physical Exertion - physiology; Physiological aspects; Risk factors; Running; Running - physiology; seuil; symptômes gastro-intestinaux; threshold; Young Adult
• ISSN: 1715-5312; 1715-5320
• DOI: 10.1139/apnm-2020-0883

Strenuous exercise increases gastrointestinal damage, but the dose–response relationship is yet to be elucidated. It is also commonly believed that running causes greater gastrointestinal damage than cycling. Two randomised, crossover studies aimed to 1) quantify gastrointestinal damage with increasing exercise intensity, and 2) determine if running was associated with greater gastrointestinal damage than cycling. Following a maximal oxygen uptake (V̇O 2max ) test, participants completed 3 cycling trials at different intensities (60 min at 40%, 60% and 80% V̇O 2max ; n = 10 (5 female, 5 male)) (INTENSITY), or 1 running and 1 cycling trial (45 min at 70% V̇O 2max ; n = 11 (3 female, 8 male)) (MODE). Venous blood samples were collected pre- and post-exercise to measure gastrointestinal damage via intestinal fatty acid binding protein (I-FABP). In INTENSITY, I-FABP magnitude of change was greater at 80% V̇O 2max than 40% V̇O 2max (p < 0.01). In MODE, I-FABP magnitude of change was greater with cycling (mean (SD)) (84.7 (133.2)% d = 1.07) compared with running (19.3 (33.1)%, d = 0.65) with a moderate effect (d = 0.68, p = 0.024). Rating of perceived exertion (RPE) and heart rate (HR) were higher during cycling (RPE p < 0.0001; HR p < 0.0001) but rectal temperature was not different between modes (p = 0.94). While gastrointestinal damage increases with increasing exercise intensity, running was not associated with greater gastrointestinal damage than cycling. Novelty: A fraction of the anaerobic threshold, rather than a fraction of V̇O 2max , may be more predictive of intensity that results in exercise induced gastrointestinal damage. The mode of exercise may not be as important as intensity for inducing gastrointestinal damage. Improving anaerobic threshold may reduce susceptibility to gastrointestinal damage when exercising at high intensities.