Have you ever felt sick after a hard workout? Does that post-workout protein supplement give you the runs? Believe it or not, both can be related to the toll exercise takes on the integrity of your intestinal tract. Surely, most of us agree that physical activity is crucial for good health. Regular exercise helps control weight, as well as combat many health conditions – such as stroke, metabolic syndrome, type 2 diabetes, depression and a number of types of cancers. Exercise also boosts your mood, increases energy, improves sleep and can enhance your sex life. Too little exercise has the opposite effect. A sedentary lifestyle can cause a compromised immune system, insulin resistance, inflammation throughout the body, heart disease, and constipation, among many others. It’s clear that we need to exercise for good health. But is there such a thing as too much exercise?
It would seem logical that if exercise is so good for us, then the more we exercise, the healthier we are. However, that may not be the case and here’s why.
Studies have shown that too much exercise (mainly high intensity and/or endurance training) may cause dysregulated cortisol, in addition to increased susceptibility to autoimmune diseases and infection. Cortisol is the hormone our body releases when under stress. Chronically high levels of cortisol can increase your risk for a variety of health issues, such as sleep disturbances, digestive issues, depression, weight gain, and memory impairment. Excess cortisol also encourages fat gain, especially around the mid-section.
In addition, strenuous exercise for prolonged periods of time may also cause intestinal permeability, also known as leaky gut. Basically, this means that things can get across the gut barrier that aren’t meant to, such as bacteria, food particles, waste products and toxins. This causes our immune system to become over activated and can also cause inflammation throughout our body. Definitely not a good thing! If you feel you need to eat after your workout, a good rule of thumb is to wait at least 15 minutes or longer after exercising. Make it a light snack that includes both protein and carbohydrates, and drink at least three cups of water for every pound of weight that you lost during the workout. Those pounds are water weight and should be replenished to prevent dehydration.
An increase in intestinal permeability affects a large number of people who indulge in exhaustive exercise, although it doesn’t affect everyone, and those it does are affected to different degrees.
The stress response from high intensity exercise isn’t the only thing that can alter the gut barrier. During intense exercise, your heart and skeletal muscles have a higher oxygen demand and therefore blood flow is directed away from the gastrointestinal tract and other organs (such as the liver). This process further disrupts the intestinal barrier increasing your risk for leaky gut.
However, it really depends on the intensity of the workout and the amount of rest time between sessions. The goal really is to participate in a safe and effective exercise program that improves fitness and muscle strength, without exacerbating underlying inflammation associated with any autoimmune conditions. Surely, high-intensity, short-rest workouts, such as HIIT, have been shown to increase cortisol secretion more than traditional resistance training. By contrast, regular exercise at a relatively low intensity may protect the gastrointestinal tract from becoming diseased. The evidence is strong that low intensity exercise reduces the risk of colon cancer by up to 50%, as well as the risk of gallstones, diverticulosis, and inflammatory bowel disease. This is yet another argument for increasing physical activity while avoiding strenuous exercise. Again, it’s finding balance between the two and making sure you get adequate rest in between workout sessions.
Furthermore, the use of ibuprofen, a nonsteroidal anti-inflammatory drug (NSAID), has been shown to aggravate the increased intestinal permeability caused by strenuous exercise. A study in the International Journal of Sports Medicine found that the use of ibuprofen, especially before strenuous exercise, significantly worsened both intestinal permeability and intestinal damage in well-trained athletes.
As mentioned earlier, hydration is also very important no matter how strenuous you exercise. Making sure you have adequate fluid intake before, during and after exercise can help the integrity of the the gut. Our gut health is also strongly impacted by our choices of food, as well as how we manage stress, whether or not we are able to positively reduce stressors in our life, and of course how well we sleep. All of these lifestyle factors influence each other.
So, what kind of exercise is best?
There really is no benefit to engaging in too much strenuous exercise in the gym or in other activities. Keep in mind, however, that this all depends on the individual and really listening to your body is key. The problem is this: while science can definitely point us in the right direction, the details are still up to each of us. If you’re following any type of protocol to manage chronic illness, such as leaky gut or inflammatory bowel disease, working out too hard might be holding you back from healing as much as you can. Slow and steady progress is key and exercising at a low to moderate intensity should be your aim. Taking adequate rest days between exercise sessions is also very important, as is making sure that the intensity level is appropriate for you.
As with all components of our lifestyle changes, the key is moderation and listening to your body. If you choose to participate in high intensity training programs, always use your best judgment and don’t let anyone, including yourself, push you past your comfort zone. It’s best to build up slowly over time, especially if you haven’t exercised on a regular basis, to give your body time to adapt to the new demands.
Start off by making choices to move A LOT on a daily basis. This might include taking the stairs instead of the elevator at work, parking in one of the farthest parking stalls at the mall or grocery store rather than the closest, and making sure you’re not sedentary for too long of a period. Invest in a treadmill desk if you work from home, or take frequent breaks and walk around the office to get your off your seat. The benefits will be immediate and definitely well worth it!
If you are suffering from an autoimmune condition or have leaky gut, have you found an exercise regimen that works for you? If so, I’d love to hear from you!
 Mayo Clinic Staff (2016). Exercise: 7 benefits of regular physical activity. Retrieved from http://www.mayoclinic.org/healthy-lifestyle/fitness/in-depth/exercise/art-20048389
 Booth, F.W., Roberts, C.K. & Laye, M.J. (2012). Lack of exercise is a major cause of chronic diseases. Compr Physiol, 2(2):1143-1211 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4241367/
 Zuhl, M., Schneider, S., Lanphere, K. et al. (2014). Exercise regulation of intestinal tight junction proteins. British Journal of Sports Medicine, 48:980-986 https://www.ncbi.nlm.nih.gov/pubmed/23134759
 Mayo Clinic Staff (2016). Chronic stress puts your health at risk. Retrieved from http://www.mayoclinic.org/healthy-lifestyle/stress-management/in-depth/stress/art-20046037
 Doklandny, K., Zuhl, M.N. & Moseley, P.L. (2016). Intestinal epithelial barrier function and tight junction proteins with heat and exercise. Journal of Applied Physiology, 120(6):692-701 doi:10.1152/japplphysiol.00536.2015 http://jap.physiology.org/content/120/6/692.long
 Peters, H.P.F. & DeVries, W.R. (2001). Potential benefits and hazards of physical activity and exercise on the gastrointestinal tract. Gut, 48:435-439 doi:10.1136/gut.48.3.435 http://gut.bmj.com/content/48/3/435.full
 Lambert, G.P., Boyulan, M. Laventure, J.P. etal. (2007). Effect of aspirin and ibuprofen on GI permeability during exercise. Int J Sports Med. 28(9):722-6 https://www.ncbi.nlm.nih.gov/pubmed/17436199
 Lambert, G.P., Lang, J., Bull, A., etal. (2008). Fluid restriction during running increases GI permeability. Int J Sports Med. 29(3):194-8