You probably don't think twice about the effect your tattoos can have on your health. After all, 3 out of 10 Americans have tattoos, according to recent data from The Harris Poll, so they're totally the norm. (Not tatted? Check out these cool fitness tattoos that just might make you want to get inked up.) But a recent study from Medicine and Science in Sports and Exercise shows that exercisers should pay special attention to the potential dangers.
When researchers looked at the sweat rate in tattooed versus non-tattooed skin, they found that tattoos actually blocked sweat secretion by up to 50 percent. Sounds awesome, right? (Going to tattoo my armpits RN.) But sweating is your body's way of releasing heat. It's essential that you be able to cool down efficiently, especially during a workout.
Since tattoo ink is injected directly under the skin at around the same depth as your sweat glands, it interferes with their production of sweat, says Maurie Luetkemeier, Ph.D., lead study author. The sodium concentration in the sweat of tattooed skin was also higher than in un-inked skin, which likely indicates that the ink prevents some of the natural sodium from your sweat from being reabsorbed into the body. It's unclear yet whether this could lead to a nutritional deficiency, but it is a possibility.
The good news? You're probably fine if you've got one or two smaller designs, because the non-tattooed skin will be able to compensate for the small percentage of tattooed skin, says Luetkemeier. But the more ink you have, the greater your risk could be of overheating. If you have large areas covered with tattoos (like full sleeves), being aware of the risk can help you avoid heat exhaustion. The study used a chemical stimulus to invoke sweating in a small portion of skin—and didn't actually heat people up—but apply that same effect to your whole body sweating (like during a workout) and you could be in trouble.
You need adequate fluid to be able to sweat in the first place, so for highly tattooed individuals this becomes even more important, says Luetkemeier. "Regardless of the effect tattoos may have on your sweat glands, you'll at least have those fluids available," he says. So if you're heavily inked, remember to hydrate before, during, and after your workout. You may also want to consume extra electrolytes to replenish your sodium.