Gastrointestinal (GI) bleeding can occur in marathoners and other endurance athletes. Early studies suggested that about 2% of marathoners occasionally had seen blood in their stools, especially after a long, hard run, and about 20% had occult fecal blood after a marathon (6). Recent reviews of lower GI distress in endurance athletes and of exertional abdominal pain in athletes note how common diarrhea is in marathoners, for example, and cover the common causes of GI bleeding in athletes (11,22). Both mention GI ischemia or colonic ischemia but, because they are general reviews, do not delve into the details of ischemic colitis in athletes. Ischemic colitis is considered here.
Case Reports of Ischemic Colitis
More than 15 cases of ischemic colitis in athletes are reported in the medical literature, and other cases over the years are known among the medical community. Most involve lower abdominal crampy pain and bloody diarrhea in distance runners in training or in marathons or triathlons. A report in 1981 briefly described two likely cases in runners (2). In another early report, a 33-year-old runner had bloody diarrhea three times after marathons. On colonoscopy, he had an ischemic lesion in the cecum (21). Another was a 34-year-old female runner with abdominal crampy pain and bloody diarrhea during a 15-km mountain race. She had ischemic colitis of the ascending, transverse, and descending colon (10). A 42-year-old man had abdominal crampy pain and bloody stools during an 8-mile run, which was longer than usual for him. He had hemorrhagic ischemic colitis of the cecum and ascending colon (17).
Ischemic colitis can even require subtotal colectomy, as in a 42-year-old female runner who had bloody diarrhea for days after a grueling half-marathon in the heat. She had a subtotal colectomy for severe ischemic colitis of the transverse and descending colon (1). The same occurred in an elite female triathlete who struggled to finish the 1993 Ironman Triathlon Championship in Kona (7). In the 1997 Ironman in Kona, it happened again, this time to an elite male triathlete who vomited repeatedly while on the bike but held third place early in the run, although the vomiting continued and severe diarrhea began after 10 km. He was in sixth place near the end of the race when he began to stagger, then crawl, and then, about 50 m from the finish line, could go no further. The next day, he had a right hemicolectomy for ischemic colitis (18). Both these triathletes returned to racing.
Another dramatic case was in the 100th Boston Marathon. An elite female athlete developed crampy lower abdominal pain and bloody diarrhea at the 4-mile mark. Not to be denied, she kept racing, and although her symptoms worsened near the end, she won the race! At this point, she passed frank blood without stool and was rushed to an emergency room. Sigmoidoscopy showed ischemic colitis of the rectum and especially the sigmoid colon. On supportive therapy, symptoms resolved in 1 d, and results of sigmoidoscopy after 6 wk were normal. She returned to top racing (13).
Other cases of ischemic colitis have been reported after the Boston Marathon, for example, three women, aged 26 to 39 yr, who developed crampy abdominal pain and bloody diarrhea during or right after the race and were hospitalized within hours to 2 d after finishing the race. All three improved quickly on supportive therapy (20). All three had computed tomographic (CT) scans showing thickening of the wall of the cecum and ascending colon, consistent with ischemic colitis (12). Similar CT findings were seen in a 31-year-old man who developed lower abdominal crampy pain and bloody diarrhea in the London Marathon, collapsed at the end, and, over the course of 2 d, developed signs of peritonitis requiring right hemicolectomy (4).
Some triathletes have had bloody diarrhea not only in the running phase but also in the swimming and the cycling phases of the race (6). Ischemic colitis occurs mainly in endurance athletes, although one case has been reported in a 27-year-old male novice scuba diver (9) and another in a 21-year-old jujitsu athlete after a kick to the abdomen (19).
Debate on the Mechanism of the Colitis
A recent article questions the "four widely held tenets" of ischemic colitis: 1) the colon is particularly sensitive to ischemia; 2) ischemic colitis often is preceded by global hypoperfusion; 3) the most vulnerable portions of the colon are the "watershed areas," including the splenic flexure and the rectosigmoid; and 4) colonoscopy with biopsy confirms the diagnosis. It offers evidence against each of the four tenets and proposes that ischemic colitis is a spectrum of diseases, including some cases that are clearly ischemic and others that are infectious or idiopathic (3).
Most clinicians, however, hold that although the clinical presentation of ischemic colitis is not specific, the most common mechanisms are hypotension and hypovolemia caused by dehydration or bleeding that results in systemic hypoperfusion (8). Considering the settings, this seems true for most cases of ischemic colitis in athletes. After all, during exercise in the heat, increased sympathetic tone reduces blood flow to the gut by 50% to 80%, diverting blood to the central circulation to sustain cardiac output and to the skin to shed heat. Hyperthermia, dehydration, and hypovolemia can reduce blood flow to the gut further, causing ischemia in areas of the colon marginally perfused because of individual variation in the anatomy of the collateral blood supply (8,18).
Also, during prolonged exercise, there is an ongoing need for intestinal function to absorb fluids, electrolytes, and nutrients. This may worsen the "mismatch" between visceral supply and demand in the endurance athlete while in the heat (16). One can imagine that, faced with filling three "pools" - central, skin, and gut - with increasing dehydration and hypovolemia, the body will shut down the gut pool first. The result is ischemic colitis.
Drugs or supplements, in theory, also may contribute to ischemic colitis, for example, vasospasm from overusing sumatriptan (15) or from pseudoephedrine (5) or enhanced hyperemia of muscles, as in a military athlete taking the supplement NO-Xplode (14).
Pearls for Prevention
Some athletes seem prone to ischemic colitis. This may stem from anatomic variations in the circulation of their colon and/or from medications or supplements they take. However, it also seems to stem from heroic attempts to endure grueling races, often in oppressive heat. Because intensity plays a role, gradual conditioning for the event is prudent. Avoiding major dehydration is key. Energy intake should match needs, about 250 to 400 kcal·h−1 (18). Using nonsteroidal anti-inflammatory drugs may be unwise (16). What is most important is knowing when to stop. The onset of lower abdominal crampy pain - and especially bloody diarrhea - means it is time to stop, rest, hydrate, and, if problems continue, get medical help.
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