I'm sure a lot of my clients wonder why I make them do the overhead squat, so here it is in a nutshell. MOBILITY AND STABILITY If you suffer with any of the following: A rigid thoracic spine that can't extend. A weak core. Inflexible hips, knees, and ankles or pectorals that pull the shoulders and upper back forward. Then doing overhead squats can help relieve these issues and make your body limber. THORACIC EXTENSION Most people sit hunched over a desk all day, this puts your torso into constant flexion, your shoulders and scapulae are pulled forward, making it uncomfortable when your arms are behind your head.