Distance-running's well-studied benefits -- weight loss, a stronger set of legs, and a highly tuned cardiovascular system -- don't come cheap. Runners are well aware of the high stress placed on the leg muscles, joints, tendons and bones. Less likely to come to mind as a typical source of pain or soreness is the gastrointestinal tract -- in particular the distal end of it. Rectum pain while running, however, is more common than many runners realize.
Sources of Pain
Mark Jenkins, M.D., of Rice University notes that rectal pain during running can be divided into two types -- musculoskeletal and nonmusculoskeletal. Musculoskeletal sources, which are not as common, usually originate in the lower part of the spinal column, i.e., the sacrum or coccyx. Nonmusculoskeletal rectum pain is a more frequent offender and may involve a weakening of the pelvic floor muscles, especially in women; a partially prolapsed rectum; and various types of neurogenic pain resulting from mechanical pressure on the perineal nerve.
Hemorrhoids
According to "Running Times" magazine, hemorrhoids are, from a pathological perspective, similar to varicose veins in the lower leg. Hemorrhoids situated more deeply in the rectum cause no pain, but may bleed prodigiously. External hemorrhoids, on the other hand, are painful but less likely to bleed. The increase in abdominal pressure seen with running may cause clots to form in the affected rectal veins. This condition is painful, and a surgeon will need to remove these clots. Stay well-hydrated and coat your hemorrhoids with petroleum jelly before a run to avoid irritation.
Proctalgia Fugax and Levator Ani Syndrome
Proctalgia fugax is believed to be caused by a spasm of the muscles of the pelvic floor, and a closely related condition, levator ani syndrome, involves spasm of the nearby anal sphincter. Both are characterized by shooting pains in the anus and rectum. According to the Patient UK website, proctalgia fugax affects at least 8 percent of the population in the developed world, and levator ani syndrome around 6 percent. They may be associated with irritable bowel syndrome or a low-fiber diet. Pain usually abates as suddenly as it strikes, and the condition is benign despite the discomfort it causes. As of 2011, there was no known cure, but medications, biofeedback and botulinum toxin injections all showed promise in managing symptoms.
Anal Fissure
Anal fissures, or tears in the mucosa of the anus, are usually caused by passing a large, dry stool or by sustained diarrhea. Pain usually strikes the anorectal area during a bowel movement, and the toilet tissue may come away bloody. These usually heal on their own, but stool softeners and dietary modifications -- such as adding bulk fiber, like that found in many cereals, to promote water absorption in the colon -- can help prevent a recurrence. Topical analgesics can ease discomfort during the healing process.
