What is a butt wink?

The butt wink isn't the name of a weird sex position or new dance move.

It's actually a term for when your tailbone tucks underneath your body during a squat. "When your squat reaches a certain depth, the range of motion in your hips may become limited," says Sean De Wispelaere, a Thrive Training Systems coach. "To compensate, your pelvis tilts backward and pulls your lower back with it." Hence, the wink.

Without weight, the butt wink isn't a cause for alarm, says De Wispelaere. However, adding weight to the movement puts your spine in the danger zone. Here's why: the weight compresses the disks in your lower back. Then, rounding your lower back - like you do when you butt wink - increases the pressure to these disks, moving them out of alignment and making them vulnerable to herniation.

It helps to have someone check your form, so ask a friend or trainer at the gym to watch for your butt wink. If you're alone, perform a squat in front of a mirror. Take note of the moment your tailbone starts to tuck underneath you. "Stop right before that moment every time," says De Wispelaere.

Not everyone has the same danger point - your anatomy has a lot to do with when your butt wink actually happens during a squat.

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