The Effect of Exercise on the Gastrointestinal Tract1

Abstract

Surveys of athletes, primarily runners, have shown that digestive disorders are common, associated both with training and racing. Women, in particular, seem to suffer most commonly. Nearly half have loose stools and nausea and vomiting occur frequently after hard runs. Diarrhoea, incontinence and rectal bleeding occur with surprising frequency. Runners may use medications prophylactically to minimise some of these symptoms. Upper digestive symptoms seem to occur more commonly in multisport events such as triathlons or enduro. The published literature is difficult to analyse and the basic intestinal physiology not well studied. Most gastroenterologists are accustomed to evaluating the fasting patient at rest and exercise physiologists are seldom experienced with digestive techniques. Digestive symptoms occurring with exercise referable to the oesophagus include chest pain, gastro-oesophageal reflux symptoms, or symptoms related to alterations in motility. While little is known of the oesophageal physiology during exercise, it is believed that only minimal changes occur in most subjects. Gastro-oesophageal reflux occurs more frequently with exercise than at rest and may produce symptoms of chest pain suggestive of ischaemic disease. Acid exposure may be reduced by pretreatment with histamine H2-receptor antagonists. Oesophageal symptoms, though common, are rarely disabling to the athlete, and the clinical importance lies in confusion with ischaemic disease. Cases of acute gastric stasis following running have been reported and gastric physiology during exercise, particularly bicycling, has been more actively investigated. Gastric emptying during exercise is subject to a number of factors including calorie count, meal osmolality, meal temperature and exercise conditions. However, it is generally accepted that light exercise accelerates liquid emptying, vigorous exercise delays solid emptying and has little effect upon liquid emptying until near exhaustion. Gastric acid secretion probably changes little with exercise although some have postulated that ulcer patients may increase secretion with exercise. Some exercise-associated digestive symptoms, such as diarrhoea and abdominal pain, have been attributed to changes in intestine function. Small bowel transit is delayed by exercise when measured by breath hydrogen oral caecal transit times and motility may be reduced as well. Intestinal absorption during exercise has not been well evaluated but probably changes little in ordinary circumstances. Passive absorption of water, electrolytes and xylose are not affected by submaximal effort. Colonic transit and function is even more difficult to evaluate and published results have been conflicting. However, it is likely that many of the lower digestive complaints of runners such as diarrhoea and lower abdominal cramps are due to direct effects of exercise upon the colon.(ABSTRACT TRUNCATED AT 250 WORDS)

Diagnosis and management of splanchnic ischemia

“…Splanchnic ischemia develops well before systemic hemodynamic instability arises [24] . This splanchnic vasoconstriction may be triggered by shock states, including hemorrhage, sepsis, dehydration or cardiac failure, from vasoactive medications, nicotine and cocaine abuse, or even in strenuous exercise [19,[25][26][27] or severe psychological stress [28] . This combination of ischemia despite normal vessel anatomy, has given rise to the term non-occlusive mesenteric ischemia (NOMI).…”

Vagal Nerve Regulation Is Essential for the Increase in Gastric Motility in Response to Mild Exercise

“…It has been shown in human research that mild to moderate exercise may accelerate gastric emptying, whereas severe, exhaustive exercise beyond a critical level (about 70-80% VO 2 max.) delays emptying of liquids and solids (Cammack et al 1982;Read and Houghton 1989;Moses 1990;Matsui 2000). However, the mechanism by which physical activity affects gastric motility remains elusive.…”

Gastrointestinal considerations related to youth sports and the young athlete

“…If hematochezia is present, it is likely this is the mechanism (20). Another proposed mechanism is the alteration of both small bowel and large bowel transit during periods of exercise leading to accelerated emptying (20,21). Additionally there is a mechanical model proposed for symptoms where repetitive damage is caused by the jostling of the abdominal contents during exercise leading to symptom production (22).…”

“…For non-bloody diarrhea, it may be feasible to use an antimotility agent such as loperamide or diphenoxylate with atropine (21), however the utmost caution should be used given the young age of our patient population and risks of these medications. If the diarrhea is bloody a historical review, to include travel, should be undertaken as well as the recommendation to cease all activity as well as nonsteroidal anti-inflammatory drug (NSAID) use until symptoms abate.…”