Feeling a pins-and-needles sensation during your workout might be scary (or at least so uncomfortably annoying), but aside from the disruption it presents to your sweat sesh, there’s nothing serious to worry about: This numbness of the limbs is actually pretty common.
According to Self, if your hands or feet—or anything, really!—start to tingle while exercising (AKA paresthesia), it’s typically because the blood flow to your nerves is being blocked. And that usually occurs because of certain body positioning, like running with clenched fists, for instance.
“When people are limited for time or are stressed, they tend to make a tight fist and an aggressive pumping motion during exercise, which can make the tingling or numbness worse.”
“When people are limited for time or are stressed, they tend to make a tight fist and an aggressive pumping motion during exercise, which can make the tingling or numbness worse,” Alice Chen, MD, told Self. Instead of tensing up, Dr. Chen says it’s best to loosen your grip and let your arms swing naturally.
The same goes for when you experience numbness mid-workout in your legs and feet. When you exercise, your blood flow increases—more so in the lower than upper body, said Jeffrey M. Gross, MD. This makes your muscles swell, which in turn can make your sneakers tighter. The snugness around your feet can compress your nerves and cause tingling, a sensation that can also occur when your feet stay in the same position for longer periods of time (like on the elliptical or a stationary bike).
If you start to feel the pins and needles, the cure might be involve taking a note out of Taylor Swift‘s book: “The tingling or numbness is benign as long as it goes away when you shake it out,” Dr. Chen said.
And, if that doesn’t work, take the safe route and have your doc check it check, in case something more serious is going on.