We evaluated the effect of graded exercise on esophageal motility and gastroesophageal reflux. We studied eight trained cyclists using a catheter with three strain-gauge transducers connected to a solid-state datalogger and an ambulatory intraesophageal pH monitor. Each study lasted 4 hr during which subjects exercised on a stationary bike for 1 hr at 60% of peak O2 uptake (O2 max), 45 min at 75% of O2 max, and for 10 min at 90% of O2 max. Subjects rested 1 hr before exercise (control period) and for 30 min between exercise sessions. Studies were performed after an overnight fast and subjects received only intravenous infusion of 5% glucose solution during the study. Plasma concentrations of gastrin, motilin, glucagon, pancreatic polypeptide (PP), and vasoactive intestinal peptide (VIP) were determined at rest and before and after each exercise session. The duration, amplitude, and frequency of esophageal contractions declined with increasing exercise intensity, and the differences were significant (P≤0.05) for all three variables at 90% O2 max. The number of gastroesophageal reflux episodes and the duration of esophageal acid exposure were significantly (P≤0.05) increased during exercise at 90% O2 max. Plasma hormone concentrations showed no significant changes between rest and the various exercise sessions. Thus, exercise has profound effects on esophageal contractions and gastroesophageal reflux which are intensity dependent. These effects are not mediated by the hormones measured.
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