This time of year, it seems like the running paths are packed. Whether people are training for fall races (like our CFB Reach the Beach Team) or just out because it’s finally warm, lots of people are lacing up the sneakers right now. And along with added miles comes increased likelihood for experiencing stomach issues during a run.
I think many habitual, sometimes, and “only if a bear is chasing me” runners alike probably know the feeling of having a run (or workout with lots of running) ruined by gastrointestinal distress. I have even heard the joke that you’re not a real runner until you’ve gone to the bathroom somewhere you’re not supposed to. So why does this happen?
Part of what causes this GI stress is related to physiological changes that occur in your body when you exercise. Movement – like running – stimulates the upper digestive system – then the lower digestive tract – which means things move through more quickly. In addition, as we exercise our bodies start pumping more blood to our muscles and skin, and less to our digestive tract. This can cause strain on the GI system, and sometimes results in diarrhea.
The other part of the equation is diet leading up to and during exercise. A few things tend to cause problems most often:
Problem: Fat. Fat delays the digestion of carbohydrates in the stomach, so too much fat too close to a run can mean your last meal sits like a brick in your belly.
Solution: Try to avoid foods higher in fat closer than 3-4 hours before a run. I would also advise against having a large, high volume meal close to a run.
Problem: Sugar. Many runners use sugary chews, gels, or snacks to stay fueled during the run. Others might drink Gatorade during or before a run. This is smart, obviously – readily available carbohydrates at periodic times during an endurance activity will help you maintain the activity longer. The problem, though, lies with osmosis. Remember from biology class that osmosis is the movement of water molecules between a semi-permeable barrier to the side with higher solute concentration so as to equalize the concentration on both sides. Your body likes to maintain a particular balance – known as homeostasis – and osmosis helps it do this. So when that high carbohydrate, quickly digestable fuel item of choice is digested very quickly in the stomach, it moves to the intestine. Now the intestine has a high concentration of “solute” (the sugar). Osmosis kicks in, and water is drawn into the intestine, which makes stool (that’s health professional speak for poop) looser. And I think we all know where this is going.
Solution: There are a few ways you can try to fix this. Of course, everyone is different, so it will likely come down to some self experimentation.
- Avoid certain sugars. According to a blog post on constipation by Dr. Reddy, an Associate Professor of Pediatrics and Adolescent Medicine at the Western Michigan University School of Medicine, corn syrup – along with apple, pear, and prune juices – is not absorbed very well by the intestine, and have a stool loosening effect.
- Space our your fuel – intend of eating a whole bag of chews (for some, up to 45 grams of sugar) all at once, eat 2-3 chews (or about 10-15 grams of carbs) every half hour. This will result in slower infusion of sugar to the intestine, which will avoid the large osmotic response.
- Don’t over hydrate – it’s good to drink water, of course. But water IN the intestine is kind of the problem. So having a lot of water at once, especially with your fuel, could cause the same issue. Try to sip water throughout the run/race, aiming for about 8 -16 ounce an hour.
Problem: Coffee. For some people, coffee has a minor laxative effect. While this is often attributed to caffeine research has shown that decaf coffee has the same effect, so it must be the coffee (and not the caffeine). Coffee stimulates muscle movement in the colon, which is likely the cause of this effect.
Solution: Drink your coffee 1-2 hours before you run (and try to go first), or skip the coffee until you enjoy your post-run breakfast.
Problem: Fiber. Depending on the type of fiber eaten, it can either bind up the contents of the GI tract and lead to constipation, or promote regularity. Fiber also slows digestion (like fat).
Solution: Consume foods lower in fiber within the few hours before a run.
Of course, much of this ends up being trial and error. Some runners can eat a turkey sandwich mid-run, others can only tolerate specific fuel sources. If you’re gearing up for a race, now is the time to figure out what works for you. By race day, you should have a consistent fuel and hydration plan, and stick to it.