The surprising fitness-gut health connection that could take your workout to the next level

Sure, you may know that proper pre-workout fueling can give you the energy you need to crush it at spin class or shave an extra 20 seconds off your mile time, but it turns out that there’s a lot more to the fitness-gut connection than what you eat right before. And now there’s a way to figure out which types of foods can help you improve your personal exercise performance thanks to new research by biochemist Erika Angle, PhD, who’s spent the past several years obsessively studying gut health.

The culmination of her research is a newly released at-home blood test, Ixcela, which gives users an inside look (literally) at their microbiome, AKA the millions of good bacteria living in your body. (It turns out a dreaded stool sample isn’t the only way to know.)

How it works is that 12 key markers in the blood are analyzed, and the findings can tell you what foods truly work best for your physical—and mental—health. As an experiment, Dr. Angle had all the members of Team Oracle USA, an American yachting team, take the test and then follow the recommended individualized diet plans. Collectively, their athletic performance increased by 48 percent—no small difference!

What exactly did she learn about gut health that can take your workouts to the next level? Here, she shares 3 key findings.

1. Being fit on the outside doesn’t mean you’re fit on the inside

“There’s this perception that if you’re physically fit, you’re internal health is also very good, and something I learned working with the Oracle team is that isn’t necessarily true,” Dr. Angle says. Some of the athletes she worked with actually ate like total crap and it was destroying them internally—hello, leaky gut. But on the surface, it was hard to tell because they were burning off all the fried chicken wings and French fries by working out. When they actually started changing their eating habits, though, their workouts reached a whole new level.

The takeaway here: Just because you work out a lot, that doesn’t mean you can actually eat whatever you want. It could still be causing inflammation in your body. And that could cut down your workout performance.

2. A stronger gut will boost your immune system

If you’re feeling sick or worn out all the time, you’re definitely not going to have enough energy for a workout. Dr. Angle says one common connection she’s seen is a low immune system being linked to a compromised stomach. “Processed foods, sugar, and too many carbs can lead to a breakdown in the gut, allowing things to leak out and weaken the immune system,” she says. “If you have a leaky gut, your body is too busy fighting that off, so you’re more likely to get sick.”

If you’re a swimmer or tend to shower post-workout and then head out of the locker room without blow drying your hair, Dr. Angle says this is extra important for you because it’s even easier to get sick that way due to the fact that stress caused by lowering the body’s core temp, as well as cooling the body’s surface, have both been shown to increase the likelihood of respiratory infections. 

3. A wide range of gut bacteria is key

Another commonality Dr. Angle noticed a lot of people with low gut scores shared was that they weren’t getting enough probioticsandprebiotics. “Prebiotics are really important,” she says. “Even if you take a probiotic, if you have nothing to feed them, they aren’t going to be activated.”

As she explains, you need the prebiotics to feed the probiotics, and you need the probiotics to help break down short-chain fatty acids in the body, which are used as a power source (AKA workout fuel). “The more different varieties of gut microbes you have, the more efficient your body will be at producing more energy,” Dr. Angle says. In other words, protein isn’t the only nutrient needed to supercharge your workout: prebiotics and probiotics help, too.

Now that you know how important probiotics are, here are some ways to get more. Or if you want to up your intake with a supplement, check out the brands that gut health experts actually take.