Impact of exercise duration on gastrointestinal function and symptoms

Area of Science:

• Exercise Physiology
• Gastroenterology
• Sports Science

Background:

• Exercise duration impacts physiological responses.
• Gastrointestinal symptoms (GISs) are common in athletes.
• Understanding exercise effects on gut function is crucial for performance.

Purpose of the Study:

• To investigate the effect of varying exercise durations (1, 2, and 3 hours) on gastrointestinal function and symptoms in endurance runners.
• To assess changes in orocecal transit time (OCTT) and gastric slow wave activity (GSWA) in response to exercise.
• To correlate physiological changes with the incidence and severity of exercise-associated GISs.

Main Methods:

• 16 endurance runners completed randomized 1-hour, 2-hour, and 3-hour running trials at 60% V̇o_2max.
• Orocecal transit time (OCTT) measured via lactulose challenge and breath hydrogen.
• Gastric slow wave activity (cEGG) and gastrointestinal symptoms (mVAS) recorded pre- and post-exercise.

Main Results:

• OCTT remained slow across all durations, with no significant differences.
• Post-exercise bradygastria increased significantly in all trials.
• GIS incidence and gut discomfort were higher with longer exercise durations (2-H and 3-H vs. 1-H).
• Severity of gut discomfort, total GIS, upper GIS, and lower GIS increased during exercise.

Conclusions:

• Steady-state exercise, regardless of duration, perturbs gastric myoelectrical activity and motility.
• These physiological disruptions contribute to the increased incidence and severity of exercise-associated GISs.
• Cutaneous electrogastrography (cEGG) may offer valuable insights into gastrointestinal motility during exercise.