Exercise & Digestion – how digestion is affected by movement
You may have definitely heard how impactful physical exercise is on the overall health &
body conditioning, from the increase of endorphins to the reduction in stress levels & balance of brain neurotransmitters or speeding up the metabolism, just to name a few. At the same extent, exercise can alleviate symptoms of digestive diseases and prevent constipation.
On the flip side, some people experience diarrhea and/or other digestive problems (nausea, heartburn) after an intense training session. Are you one of them or maybe just curious about the reason why this unpleasant intestinal interruption? Keep reading to learn about the causes and the many ways to prevent or mitigate these situations, along with the positive impact exercise has on digestion.
Certain types of exercise cause food to pass through the gastrointestinal tract at a more rapid pace; both strenuous bodybuilding/weightlifting and running fall into this category. The resulting side effects of a successful but intense training session may come in the form of reduced nutrient/water absorption and looser stools. In addition, the hormones that affect digestion can take a hit during workouts; given that intense exercise limits blood flow to the gastrointestinal system, hormonal homeostasis gets disrupted. While each of these situations can wreak havoc on one’s body, together they create a perfect storm for those who have sensitive digestive systems.
Running and Digestion
I have always considered running an ideal form of exercise, in terms of convenience. Put on your favorite tee shirt and shorts, lace up those running shoes, and head outside! Many of you may feel the same way. However, not everything is always as it seems, especially for individuals who live with temperamental digestive issues.
Most regular runners have at one time or another experienced the sudden urge of a loose bowel movement while running, often causing the athlete to either speedily find the closest restroom before something ugly occurs, or prematurely terminate the run. Such occurrences do not stem from any diseased state of the GI tract, but rather from a series of intricate changes taking place within the body. Intense exercise can incite a temporary negative effect on the digestion, summoning the onset of nausea, heartburn, diarrhea, and gastrointestinal bleeding. Even healthy runners seem especially susceptible to these uncomfortable circumstances.
Throughout any challenging workout, blood flow to the intestines slows as the body prioritizes the shuttling of blood to the lower extremities. While this immediate bathroom issue poses an inconvenience, engaging in intense physical exercise like running has been shown to reduce the risk of developing colon cancer.
How about exercising with IBS?
A new study was developed by the scientists in Sweden, who investigated whether physical activity represents a valid treatment for mitigating irritable bowel syndrome (IBS). The study included 102 patients, divided randomly into a physical activity group and a control group. During the 12-week trial, the physical activity group exercised 3-5 times a week, for 20-60 minutes each session, maintaining a moderate-to-vigorous level of intensity. The control group maintained their current lifestyles.
Of those in the physical activity group, 43% demonstrated a significant decrease in symptom severity, compared with only 26% of the control group subjects. The physical activity group also reported improvements in sleep, energy level, overall “life functioning” and social interactions. In addition to demonstrating that physical activity can be an effective way for some IBS patients to manage intense symptoms, scientists now know that a lack of active movement may actually lead to worsening episodes.
Suffering of GERD? Meal timing matters
The uncomfortable symptoms of esophageal reflux (commonly referred to as GERD) present themselves when an acidic food source reaches the lower base of the esophagus, and as the stomach fills. Since physical exercise too may bring about a reflux episode, experts caution GERD sufferers to time their physical activity, allowing the GI tract an opportunity to be in the parasympathetic mode (=relaxation state) and produce the digestive juices needed for a good digestion. It might help as well for sufferers of indigestion to take their time chewing the food. Make eating time a sacred ritual, by sitting down & relaxing, avoiding strenuous exercise within 2 hours of eating. Most exertional reflux is treatable by modification of exercise (for example biking in place of running) & fasting before the exercise.
Type of Exercise matters
Diverticulitis affects roughly half of our 50+ population. This ailment refers to the presence of small sac-like protrusions (diverticula) which tend to expand and push right through the outer wall of the colon. The majority of individuals do not realize this condition exists within their digestive tracts, living asymptomatically up until they experience a flare-up. These attacks potentially lead to inflammation of the region, leading to fever, infection, bleeding, and gastric pain.
Diverticular disease is more prevalent among those who have sedentary occupations. A research study followed over 18 years, the lives of approximately 50,000 males, ranging in age from 40-75 years. Data pointed to a lower incidence of diverticular disease complications in volunteers who maintained a regular physically active lifestyle. However, scientists also found that not just any mode of activity would mitigate symptoms.
Despite the prior mentioned digestion problems sometimes associated with running, the up-and-down motion of running and jogging apparently decreases pressure within the colon. This in turn provides the basis for better digestion while encouraging regular elimination. Dynamic but less vigorous activities such as tennis or cycling tends to elicit only minimal risk of diverticulitis complications, while light movements like yoga appear to have minimal to no effect on frequency/severity of flare-ups.
Can Exercise help the liver?
Individuals suffering from non-alcoholic fatty liver disease, or NAFLD, manufacture an excess of a substance called aminotransferase. Many studies reveal that exercise-induced weight loss may lead to a reduction in liver fat and/or aminotransferase concentrations.
A recent study attempted to analyze the relationship between physical activity and risk of severe NAFLD-related conditions such as advanced fibrosis. Data gathered from observing over 800 middle-aged adult patients suggests that exercise intensity might play a greater role than either duration or total volume of activity in mitigating the effects of NAFLD. It was found that only very vigorous physical activity, such as running on a treadmill, had an effect on the severity of NAFLD.
Can Exercise prevent GI cancers?
There is strong evidence that physical activity can decrease an individual’s risk of developing gastrointestinal cancers, especially colon cancer. As well, physical activity can help with other health issues that are known risk factors for colon cancer, including obesity, insulin resistance, impaired immune function, and high triglyceride levels.
One study of nearly 500,000 US men and women over an eight-year period found that physical activity may also have a preventative effect against upper gastrointestinal tract adenocarcinomas, which are often associated with GERD and Barrett’s esophagus.
Offering you appropriate digestion guidance
Many athletes, mostly runners, minimize their risks of GI disturbance with appropriate fluid intake, optimal meal timing, and limited use of non-steroidal anti-inflammatory drugs (NSAIDs). If you are living with chronic/frequent exercise-induced GI conditions, you might be steered away from engaging in a marathon. Thankfully, there are plenty of other ways of movement – yoga, tai chi, walking, jogging, biking, swimming, rowing, tennis, lifting weights. You can always find a suitable physical activity and we, as health care practitioners, can work with you to easily navigate these waters.
Key points about Exercise and Gastrointestinal conditions
Vigorous exercise may trigger gastrointestinal symptoms, which are mostly transient and do not have long-term consequences.
There is convincing evidence that physical activity reduces the risk of colon cancer.
There is evidence for the positive effects of physical activity on gastroesophageal reflux disease, ulcer disease, non-alcoholic fatty liver disease, diverticular disease, irritable bowel syndrome, and constipation.
Meal timing & the type of exercise performed have a great impact on your digestion. Bring mindfulness into your eating patterns & do your best to plan your exercise accordingly.
Cheers to Your Health!
Johannesson E, Simrén M, Strid H, Bajor A, Sadik R. Physical activity improves symptoms in irritable bowel syndrome: a randomized controlled trial. Am J Gastroenterol. 2011;106(5):915-922. doi:10.1038/ajg.2010.480
Emerenziani S, Zhang X, Blondeau K, et al. Gastric fullness, physical activity, and proximal extent of gastroesophageal reflux. Am J Gastroenterol. 2005;100(6):1251-1256. doi:10.1111/j.1572-0241.2005.41695.x
Strate LL, Liu YL, Aldoori WH, Giovannucci EL. Physical activity decreases diverticular complications. Am J Gastroenterol. 2009;104(5):1221-1230. doi:10.1038/ajg.2009.121
Kistler KD, Brunt EM, Clark JM, et al. Physical activity recommendations, exercise intensity, and histological severity of nonalcoholic fatty liver disease. Am J Gastroenterol. 2011;106(3):460-469. doi:10.1038/ajg.2010.488