The American College of Gastroenterology defines acid reflux, or gastroesophageal reflux, as the occurrence of a backward flow of gastric acid from the stomach up into the esophagus. Typical symptoms associated with acid reflux include heartburn and the regurgitation of food. The causes of acid reflux are multi-factorial, with exercise considered to be one of the contributors. It is estimated that 10 to 17 percent of athletes are affected by gastroesophageal reflux. Exercise-induced acid reflux is thought to be caused by various physiological processes.
Esophageal Motility Disorders
The esophagus transports food from the mouth to the stomach. Coordinated muscular contractions of the esophagus are required for this process to effectively clear consumed contents and, subsequently, prevent acid reflux. In susceptible individuals, exercise can impair the effectiveness of esophageal muscular activity by affecting the intensity, duration and amplitude of esophageal contractions.
Reduced Gastrointestinal Blood Flow
During exercise, blood flow is diverted away from the gastrointestinal system to the working muscles, heart and lungs. Gastrointestinal blood flow can be reduced by as much as 80 percent during physical activity. A reduction in blood flow to the colon delays waste removal and allows for stool to build up in the colon and rectum. This, in turn, delays stomach emptying, which can trigger acid reflux.
Changes in Intra-Abdominal Pressure
Kimberly L. Collings and colleagues reported that an increase in intra-abdominal pressure was likely the cause of the exercise-induced acid reflux experienced by weightlifting subjects in their investigation published in the May 2003 issue of "Medicine & Science in Sports & Exercise." Normally, the contents of the stomach are prevented from flowing back into the esophagus by the lower esophageal sphincter, or LES. When the pressure zone of the LES is greater than the intra-abdominal pressure, a barrier is created. When the intra-abdominal pressure rises above the LES pressure gradient, it causes the LES to open; thereby, allowing gastric juices to flow back into the esophagus, resulting in acid reflux symptoms.
Exercise Mode and Intensity
Physical activities that agitate the body, such as running, tend to be associated with a higher incidence of acid reflux compared to sports that involve less bodily agitation, such as cycling. Likewise, vigorous intensity exercise appears to precipitate acid reflux more so than physical activity performed at a lower intensity. Moderate-intensity exercise, however, has a protective effect against the occurrence of acid reflux.
Considerations
Chest discomfort that is associated with exercise-induced acid reflux can mimic heart-related pain. As a result, individuals who experience chest discomfort should consult a qualified health care professional for an examination and testing to rule out heart-related causes. Confirmed cases of exercise-induced acid reflux can be prevented by waiting three hours after consuming a meal before exercising. Use of anti-acids approximately four hours prior to engaging in physical activity may also offer some relief.
References
- American College of Gastroenterology: The Word on Gerd
- Mayo Clinic: Heartburn
- "World Journal of Gastroenterology;" Body Weight, Lifestyle, Dietary Habits and Gastroesophageal Reflux Disease; Davide Festi et al.; April 14, 2009
- Up To Date: Gastrointestinal Disorders in Athletes
- "AMAA Journal;" Gastroesophageal Reflux Disease in Runners; Ashish Sharma and John Levey; Winter 2003
- "Medicine & Science in Sports & Exercise;" Esophageal Reflux in Conditioned Runners, Cyclists, and Weightlifters; Kimberly L. Collings et al.; May 2003
