It happens suddenly. You’re in the middle of working up a sweat in a high-intensity boot camp, and BAM!—you need to hold yourself back from throwing up right in the middle of the floor. You panic (no one wants to be “that girl”), and you pray the sensation subsides. After class, you question whether you’re really as fit as you previously thought and desperately try to remember if you ate something weird earlier in the day. Truth is, exercise-induced nausea can affect everyone from novices to professional athletes, and what causes its onset is multi-factored and somewhat mysterious.
When you feel nauseous, whether it’s from one too many glasses of wine, being sick with the flu, or exercising, what happens in the body is the same. The sensation begins with a slowing of gut mobility. “The digestion of food slows down in the intestine as blood flow is redistributed from your gut to your working muscles,” says Daphne Scott, M.D., a primary care sports medicine physician at The Hospital for Special Surgery. This process, called ischemia, manifests itself in many different ways—nausea, constipation, or diarrhea—all of which impact the GI system.
Take a look at some of the things that are commonly thought to increase your chance of nausea while working out, and ways you can avoid this awful feeling in the future.
Although it’s always important to take the recommended dosage of any medication, Scott says to pay close attention to your intake of anti-inflammatory medicines; excessive amounts of ibuprofen or naproxen can cause nausea. So while it may be tempting to muffle your knee pain with OTC anti-inflammatories to get you through that tough workout, one too many can leave you feeling sick.
What to do: Never take more than recommended on the box or than prescribed by your doctor. And if taking an anti-inflammatory, do so post-workout instead.
Surprisingly, exercise-induced nausea can happen at any speed and at any intensity. Scott says that although high-intensity exercise can increase your chance of nausea due to the sheer fact that the harder you work, the more you ask of your body, nausea can occur at any intensity level. “This is thought to be partly due to conditioning level,” she says, but emotions and anxiety play a large role too. “If you’re stressed or have excitement about a competition. If you’re trying a new gym or new workout, the nervous excitement could cause an upset stomach.”
What to do: At the gym? Reduce your speed or resistance until the feeling subsides—usually fairly quickly after you slow down or stop moving, says Scott. In class? Scott recommends simply taking a step back, slowing down, and rejoining the group once you feel better. Stop internally competing with yourself; if you get sick, no one wins.
Although it’s reasonable to assume exercise-induced nausea can occur if a beginner pushes him or herself too hard, too fast, overall the phenomenon is not prejudiced to any skill level. In fact, GI distress is relatively common among endurance athletes like marathon runners or long-distance cyclists—some of the most “in shape” athletes in the world. One study published in the journal Appetite tested subjects of different genders and conditioning levels, asking them to fast, eat right before, or eat directly after exercise and found that food intake and intensity level affected nausea, but gender and conditioning level did not. “Training did not decrease exercise-induced nausea,” they reported.
What to do: Progress through your fitness level in stages. Don’t try an expert-level kickboxing class if you’ve never tried the technique before. There’s no shame in starting from the bottom—only up from there!
During exercise, blood flows away from your gut, towards larger working muscles. Problem is, inadequate hydration affects the volume of blood pumping through your body, which can exacerbate that GI distress and gut immobility we mentioned before.
What to do: This answer is as straightforward as it gets: drink more water, more often. And not just when you're exercising: “Be aware of your hydration throughout the week.” We also suggest eating more of these 30 hydrating foods.
Perhaps one of the largest players in the exercise-nausea game is your diet. Eating a large meal and going to boot camp shortly after is a fairly obvious recipe for disaster. However, Scott says that skipping meals or not eating a satiating balance of protein and carbs can also play a role. Too full and your stomach won’t have enough time to properly digest. Hungry? An empty gurgling stomach will have your water sloshing around in your stomach making waves. It may take some time to learn what’s best for your stomach, as it’s different for everyone, but this is a great place to start: What to Eat Before Working Out and When to Eat It.
What to do: Examine your pre-, during-, and post-workout eating habits. If you typically don’t eat for a long time before a workout, try having a small snack 30 minutes to an hour before, says Scott. Conversely, if you tend to eat a lot before exercise, try to reduce the amount of food and replace it with a smaller amount of healthy fats, carbs, and protein such as nuts or nut butter on a piece of toast, she says.
You’re familiar with the positive hormonal changes that occur with exercise (more endorphins! less cortisol!). But Scott says there are many different theories on how hormones may affect GI symptoms like nausea during exercise. “One thought is that hormones are released from the brain and lead to a release of catecholamines (hormones released by the adrenal glands), which can then cause a delay in gastric emptying,” she says.
What to do: Take a pause if you're feeling nauseous, then join the game when you're feeling better. You can still embrace these 13 Mental Health Benefits of Exercise.
In the end, exercise-induced nausea can affect anyone at any time, but there are things you can do to prevent its likelihood. And know that just because you feel nauseous doesn’t necessarily mean you’ll actually throw up in class. Its kind of a luck of the draw on that one, but stopping what you’re doing, or at the very least slowing down can stop this uncomfortable (and potentially embarrassing) feeling in its tracks. “Listen to your body,” reminds Scott. “There’s no shame if you need to stop. Just take a break, and you can always join back in.”