Function of the lower esophageal sphincter during and after high-intensity exercise

Introduction: Gastroesophageal reflux is commonly reported during high-intensity endurance exercise in otherwise healthy asymptomatic individuals. Although the mechanisms underlying this exercise-induced reflux are unknown, it most likely reflects a failure of the primary barrier to reflux, the lower esophageal sphincter (LES). The aim of this study was to determine the influence of exercise with and without ingestion of fluid on the LES barrier pressure in asymptomatic individuals. Methods: Seven recreational cyclists (five males) performed four 5-min bouts of cycle exercise at 90% V̇O_2max, each separated by 1-3 min. Before, during, and after exercise, measurements were made of esophageal pressure (Pes), LES pressure (PLES), and gastric pressure (Pg). LES barrier pressure (PB) was defined as the difference between PLES and Pg. Following exercise bouts 2 and 3, subjects ingested 600 and 200 mL of a sports drink, respectively. Results: PB before exercise was 13.1 ± 5.2 cm H₂O (± SD), decreased to 6.5 ± 4.6 cm H₂O during each of the four bouts of high-intensity exercise (P < 0.05), and remained decreased at 7.4 ± 3.5 cm H₂O after exercise (P < 0.05). Conclusions: High-intensity exercise reduces LES PB during exercise in asymptomatic individuals. The magnitude of this exercise-induced impairment in LES function is unaffected by ingestion of a sports drink.