
The psoas is an amazingly strong muscle that flexes the hip. Its attachments run from lumbar spine across the front of the pelvis and down to the front of your femur. If it becomes short and locked-down it changes the entire mechanics of your pelvis, low back and general posture. This can be a major contributor to hamstring injury (we'll save that for another post).
The psoas gets wrecked by sitting and having that chronic shortening from 6-10 hours a day of being immobilized. Below is a great video by Kelly Starrett and how that can jack up your mechanics and your everyday posture. If you have questions about how to fix those issues check out Mobility WOD or use the contact form on the right to ask and I'll pass some great ideas along.