6 Ways Your Workout Can Change Your Poop

Here's why exercise may send you running to the toilet, plus other effects it can have on your system.

You're 45 minutes into barre class when it hits you, suddenly and without warning: the urge to go. Your stomach just gurgled so loudly, you're certain the woman plié-ing to your left heard it too. You glance at the clock on the studio wall, and try to gauge whether you can make it till the end of the hour.

If this scenario sounds familiar, you should know you're not alone: Nobody wants to discuss their exercise-induced bowel movements, "but it's a common problem and worthy of being brought out of the closet ... or out of the bathroom," says Nancy Clark, RD, author of Nancy Clark's Sports Nutrition Guidebook.

Clark has had clients ask her, "Am I the only person who carries toilet paper with me on a run?" The answer is definitely not. Lots of fit folks experience gastrointestinal issues mid- or post-workout, she says, ranging from loose stools to constipation. And for some people, physical activity can actually have a positive impact, helping to alleviate digestive woes. Here are six ways breaking a sweat can affect your system.

Your intestines get jostled a bit

The more you move, the more your intestines move. "Movement will affect digestion because it will help move food contents, gas, and stool along the digestive tract," says gastroenterologist Sophie Balzora, MD, assistant professor of medicine at NYU Langone Health. As a result, you may feel a sudden need to go. This is actually why many doctors recommend exercise to people who are chronically constipated, Dr. Balzora adds.

Any type of activity can get things moving, but running is a well-known culprit: "Runners are more likely to complain about intestinal problems than, say, cyclists, who stay more steady," Clark says.

Your blood flow changes

When you exercise, "your body will divert blood to the muscles that are doing most of the hard work," says Dr. Balzora. Your digestive system is a lower priority, and that can lead to diarrhea—aka runner's trots.

This problem is more common among newbie runners, says Clark. Increasing your mileage too quickly can do a number on your digestive system. To spare yourself emergency trips to the toilet, follow the standard advice to ramp up by about 10% each week. "Sometimes it's about training the intestinal tract to get used to a longer distance," she says.

If your symptoms persist though, it may be worth seeing a doctor. Your workouts could be aggravating an underlying condition like irritable bowel syndrome or Crohn's disease.

You may get dehydrated

When your workout leaves you drenched in sweat, make sure you drink enough to rehydrate—or you could end up with a bout of constipation (as well as a slew of other health woes). If you get backed up, try drinking more water throughout the day, Clark says. You'll know you're hydrated when you need to pee every two to four hours, and your urine is light yellow in color.

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Your pre-workout snack might screw with your digestion

Fiber is generally good for your system, but eating too much of it right before you exercise can lead to gas, cramping, or the urge to poop—stat, says Dr. Balzora.

It may take some experimentation to figure out which foods work best for you (and your bowels) before a workout, says Clark. "Some people have cast-iron stomachs—they could have a can of baked beans and go for a run and everything is fine! Other people would say no to baked beans for two or three days before." Safer choices include bananas, granola bars, oatmeal, or toast with peanut butter, Clark says.

And if you rely on sports gels or chews to power through a long run or ride, check the ingredients. Artificial additives and sugar substitutes can also lead to loose stools, says Dr. Balzora.

RELATED: What to Eat Before and After Every Kind of Workout

Yoga may soothe your system

Like running and other types of exercise, yoga can stimulate BMs, says Dr. Balzora, especially if you're constipated. But the effect might not be entirely due to bending and twisting your body. "We know the brain-gut connection is quite strong, and anxiety and stress can cause us to have abdominal pain or discomfort and irregular stools," she explains. By lowering your stress level, yoga may also help soothe your digestive woes too.

What's more, practicing yoga may strengthen some of the pelvic floor muscles that keep things moving through the GI tract, says Marc Sonenshine, MD, a spokesperson for the American Gastroenterological Association.

Regular exercise can help keep you regular

Sedentary folks are more likely to find themselves backed up, says Dr. Balzora. And although a lack of physical activity is likely just one of several factors that cause that constipation, getting consistent exercise can't hurt. "Becoming more active on a regular basis can help regulate the bowels," she explains.

Healthy habits in general are probably good for your bathroom habits too, says Dr. Sonenshine. "A healthy lifestyle makes for a healthy colon."

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