Why do runners get the trots? If you’ve ever stood in line for a Porta Pottie prior to a marathon, snuck off into the woods during a long run, or seen poop running down a competitor’s leg right before crossing the finish line, you know what I’m talking about. In a meta-analysis of over 1000 people who ran an average of 26 hours per week, 40% reported runner’s diarrhea (Mann & Singh, 2015). Most athletes love their sport sooooo much that a little bit of pain, injury, or incontinence isn’t going to deter them from an activity like it would the general population. Why is diarrhea and GI upset more common in runners and how might a pelvic health specialist help? P.S.: it might even improve your running performance!

Runners experience more frequent and looser bowel movements (Sullivan & Wong, 2004). In a study regarding gastrointestinal disturbance in athletes, 49% reported bowel urge and diarrhea but predominantly only during running (Sullivan, 1987). This begs the question what is it about running that causes these issues? The research points to causative factors being anxiety and intensity of exercise.

Anxiety

Running stimulates the sympathetic nervous system commonly referred to as our ‘fight or flight’ system. Running, by nature, is a primal activity and can be necessary for survival. While running, adrenaline levels increase and blood is shunted away from the gut; these two factors alone can cause bowel dysfunction. Even a strong rush of adrenaline can induce diarrhea. How many times have you heard, “I was so scared I almost sh*t my pants?” Furthermore, peaks of adrenaline can also cause nausea and vomiting (a couple of other common GI issues for runners). And speaking of upper gastrointestinal disorders, GERD in runners can also be explained by a drop in parasympathetic activity; esophageal peristalsis is decreased (the action which propels food from the mouth to the stomach) and lowers sphincter tone in the esophagus leading to reflux (Cronin, 2016).

Intensity of Exercise

Fecal urgency is a common phenomenon in runners.

Mechanical disruption and altered blood flow to the colon can lead to abdominal cramping diarrhea, urgency and bowel leakage. The psoas muscle (a hip flexor imperative for running) has an intimate relationship with the large intestine. The right hip flexor lies behind the junction where the small intestine connects with the beginning of the large intestine. The left hip flexor is behind the descending and sigmoid colon which is close to the end of the gastrointestinal tract. Heel strike during running creates vibration through the abdomen which can jostle the large intestine increasing the speed of colon transit leading to more frequency. Depending upon a patient’s presentation, visceral mobilization to the mesentery providing blood supply to the gut, as well as large and small intestine, could assist with blood perfusion and healthy mobility of the gastrointestinal system. Furthermore, therapeutic exercise and manual therapy to the hip flexors might also decrease bowel urgency.

I do want to note that blood in the stool after a long run needs to be addressed by a medical doctor. Blood in the stool after high-intensity exercise could indicate gastrointestinal bleeding. CT scans show that blood flow to the gut can be reduced by as much as 80% during exercise (Schwartz et al, 1990). Decreased blood flow and extended periods of mechanical jostling could cause trauma to the large intestine leading to colonic ischemia and/or gastritis. Important to note here is endurance athletes may alleviate muscle soreness and body pain with NSAIDS (non-steroidal anti-inflammatory drugs). Schwartz notes that NSAIDS “should be discouraged during the marathon period as dehydration can potentially exacerbate some of the NSAID associated problems.”

Urge

A sudden feeling of needing to poop is called bowel urgency and commonly experienced while running. Dr. Sullivan attributed urgency while running to a “progressive, culmination in severe rectal spasm.” He did not specify what could be causing the rectal spasm; prolonged shunting of blood flow away from the intestinal tract perhaps? However, he is correct that increased tone of the internal anal sphincter (a muscle you do not voluntarily control) can cause fecal urgency. A pelvic rehabilitation specialist can evaluate a patient to determine the resting tone of the internal and external anal sphincters. If the external anal sphincter (the muscle you engage in the rectum to hold back stool or gas) has difficulty relaxing, this could also contribute to fecal urgency. A therapist can help identify factors contributing to an ‘over-active’ pelvic floor. Kari Bo, a known researcher of pelvic floor function states, “elite athletes develop a stiff and rigid pelvic floor…it is unlikely that the athletes would be aware of their pelvic floor during activity” (Bo, 2015) Coordination training, manual therapy and down-training can help decrease pelvic floor resting tone. Visualization, a technique to calm the autonomic nervous system, may help with training as well as reduce urgency associated with anxiety before a race. Finally, a food and bowel diary can help determine urge triggers such as types and timing of foods. For example, runners should know that sport drinks and gels can shift water into the colon contributing to diarrhea (Chase et al, 2012).

Fecal Incontinence

The external anal sphincter shuts the door to the rectum maintaining bowel continence. This muscle is a part of a bigger group of muscles commonly referred to as the pelvic diaphragm or pelvic floor. Running requires the pelvic floor to provide stabilization through the pelvis during high impact, endurance activities. Pelvic floor fatigue could be a reason for bowel incontinence; in essence the role of stabilization wins over continence (smart…although the body is protected, the ego can still hurt). Assessing strength and endurance of the pelvic floor as well as a thorough orthopedic assessment is crucial to treating fecal incontinence.

Be in the know!

I write about taboo topics that a lot of everyday people say, “Why didn’t I know about this?!” If you want the scoop on common pelvic health conditions subscribe to my monthly Everyday People Newsletter. If you live or vacation in the beautiful mountain town of Asheville, NC…feel free to book a physical therapy evaluation.

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That’s a wrap!

Happy Runs (of the good kind)!

Article written by Susannah Haarmann, PT, WCS, CLT

Susannah is a board-certified Women's Clinical Specialist by the American Physical Therapy Association. She is a private practice owner in Asheville, North Carolina and teaches internationally in pelvic health and breast oncology rehabilitation. Susannah is an advocate of conservative treatment for pelvic health conditions and writes books and courses on pelvic health and breast cancer rehabilitation.

Resources:

· Bo, K. Handbook of Sports Medicine and Science, The Female Athlete, Chapter 8, 2015.

· Choi SC, Choi SJ, Kim JA, et al. The role of gastrointestinal endoscopy in long-distance runners with gastrointestinal symptoms. Eur J Gastroenterol Hepatol 2001;13:1089–94.

· Cronin O, Molloy MG, Shanahan F. Exercise, fitness, and the gut. Curr Opin Gastroenterol 2016;32(2):67–73.

· Diduch, BK. Gastrointestinal Conditions in the Female Athlete. MD Clin Sports Med 2017; 36, 655–669 http://dx.doi.org/10.1016/j.csm.2017.06.00.

· Grames, C, Berry-Cabán, CS. Ischemic Colitis in an Endurance Runner. Case Reports in Gastrointestinal Medicine 2012 https://doi.org/10.1155/2012/356895.

· Ho GW. Lower gastrointestinal distress in endurance athletes. Curr Sports Med Rep 2009;8(2):85–91.

· Schwartz AE, Vanagunas A, Kamel PL. Endoscopy to evaluate gastrointestinal bleeding in marathon runners. Ann Intern Med 1990;113:632–3.

· Sullivan, SN. Overcoming Runner's Diarrhea, The Physician and Sportsmedicine 1992; 20:10, 63-68, DOI: 10.1080/00913847.1992.11947502

· Sullivan, S. Exercise-Associated Symptoms in Triathletes. The Physician and Sports Medicine 1987; 15:9, 105-108,DOI: 10.1080/00913847.1987.11702083

· Sullivan SN, Wong C, Heidenheim P. Does running cause gastrointestinal symptoms? A survey of 93 randomly selected runners compared with controls. N Z Med J 1994;107:328–31.

Bowel Urge, Diarrhea & Fecal Incontinence in Runners; Can a Pelvic Therapist Help?