Raise your hand if you sit in a desk chair for most hours of the day. Chances are, this describes most of our 9-to-5 routines. While it's the ideal position to crank out that client presentation, sitting for long periods of time puts you at risk of early death, and it could be to blame for running pain too.

Dead-butt syndrome—aka the literal pain in the butt you feel when your gluteus medius is inflamed—comes as a result of sitting for extended periods of time and jumping straight into your workout without stretching your hip flexors first, explains Wendy Winn of New York Custom Physical Therapy in New York City.

By opening up your hip flexors, which get tight from sitting too long, your glutes prepare to activate instead of simply turning off when you hit the pavement, Winn says. It's called reciprocal inhibition, which means muscles on one side of the joint must relax while the muscles on the other side contract. Here's what it boils down to: When your hip flexors are on, your butt muscles are off. And trying to turn your butt "on" to power you through that evening run without stretching first can result in pain and injury, Winn says. Luckily, she's got a few simple exercises to help get your rear in gear.