"Hearst Magazines and Yahoo may earn commission or revenue on some items through the links below." If you’re out here like, “WTF is a psoas?” listen up: The psoas muscle and it’s PIC, the iliacus ...

The iliopsoas muscle is the major flexor of your hip joint. It’s made up of two muscles: the iliacus, the psoas major. These muscles work together to flex your hip, as well as stabilize your hip and ...

Proprioceptive neuromuscular facilitation (PNF) is a form of assisted stretching. It combines passive stretching with muscle contraction. First, your partner applies force to stretch your muscle ...

Beth Skwarecki is Lifehacker’s Senior Health Editor, and holds certifications as a personal trainer and weightlifting coach. She has been writing about health for over 10 years. We stretch for lots of ...

Brad and Mike demonstrate how to stretch your stiff hip after sitting.

Stretching at the end of your workout can help boost your flexibility, reduce the risk of injury, and decrease muscle tension in your body. It can even help improve your performance the next time you ...