CYCLING PERFORMANCE TIPS

The Athlete and the GI Tract

I. A quote from Derek Clayton - after his world record marathon run (Runner's World, 1977):

"Two hours later, the elation had worn off. I was urinating quite large clots of blood and I was vomiting black mucus and had a lot of black diarrhea. I don't think too many people can understand what I went through for the next 48 hours."

II. JAMA 1980:

A 24 year old medical student and long distance runner presented with a history of bloody diarrhea. He complained of three weeks of abdominal cramps after hard runs and 1 week of blood mixed with loose stools. He sought medical advice and his evaluation including a sigmoidoscopy, Ba Enema, and Upper GI/small bowel follow through were all negative. He continued his strenuous running schedule and his symptoms gradually disappeared. In the subsequent two years, he remained asymptomatic with the exception of occasional recurrent episodes of diffuse abdominal cramping, watery diarrhea, and rarely bloody diarrhea - almost always associated with particularly strenuous physical exertion such as a marathon run.

III. JAMA 1981:

A 17 y/o man ran competitively in short sprint events, and often had bouts of abdominal cramps during and after hard runs (both training and competition). After a particularly vigorous training session, he developed a dull, aching epigastric pain which then migrated to the RLQ and was associated with bloody diarrhea. When rebound and an elevated WBC developed, a tentative diagnosis of appendicitis was made and the patient went to laparotomy. A surgical diagnosis of Crohn's disease was made, but biopsies demonstrated only non specific colitis. The patient resumed running and has had no further abdominal symptoms.

These three stories raise several questions. And as I suspect many of you have had digestive tract symptoms during running or another athletic event, these may be questions that are personal as well.

• How common are GI complaints in the athlete?
• Do GI problems (and the extremes illustrated by these three stories) impact only those competing at the limits of physical exertion?
• What is the physiology at work here?
• How would I counsel a patient who asked me about similar (although hopefully not as severe) complaints?

1. During Triathlons, GI complaints are more common than musculoskeletal injuries.

2. GI symptoms may limit an athlete's performance. They are not only distracting, but may lead to dropping out of the training session or competition.
   • lower GI symptoms (diarrhea, need for a bowel movement, fecal incontinence) are the most common reason athletes stop exercising, followed by abdominal cramps
   • in a survey of 109 distance runners
     • 43% had nervous diarrhea before competition
     • 60% had to stop for a BM during training
     • 12% had to stop during competition for a BM
     • 47% had severe cramps during or after a hard run or competition
     • 16% saw blood in their stool after a hard run

3. GI symptoms may suggest the presence of underlying GI disease.
   • epigastric and chest discomfort can suggest the possibility of ischemic heart disease
   • diarrhea and rectal bleeding raise the specter of inflammatory bowel disease and even malignancy.

4. GI symptoms may limit oral intake, and as a consequence performance, during an event.
   • This is a critical issue for participation in events lasting more than 2 hours where endogenous glycogen reserves are depleted and, if not replaced or supplemented beforehand, performance is impacted.
   • Depending on the duration of the event or ambient temperature/humidity, this may contribute to dehydration and decreased performance.