This is one of the hardest Squat variations you can do, and one of my favourite exercises! The Overhead Squat works both your upper and lower body, activating muscles including the quadriceps, hamstrings and adductors from the lower body and the triceps and deltoids from the upper body.
Start by picking the bar up off the floor. You should grip the bar with a 'super-wide' grip (approximately 2 shoulder widths wide). From here take the bar up into your body in a front rack position and then press the bar up towards the ceiling. The bar should be directly over your centre of mass and should feel stable. This is your starting position. Next, squat down into your squat position. You will find that as you do this the bar should come slightly backwards to prevent you toppling forwards. The only difference from a normal squat here is that our knees and our toes are angled a little wider to help us get lower into the squat and alleviate some of the tightness in the shoulders.