Set-up: Set your feet slightly wider than shoulder width, brace your stomach and establish a neutral spine posture. Raise your chest up and look forwards and slightly upwards.
Lift: Start the movement as if you were about to sit down, pushing your hips down and back. Descend as far as you can without excessive rounding of the back and without the knees caving inwards. Drive through your heels to stand up explosively. As you extend upward, use your momentum to throw the ball overhead. Let go of the ball at the peak of your movement, aiming straight up or slightly forward if you're against a wall. Follow through with your arms and hips. Retrieve the ball or let it bounce back from the wall or floor. Reset your position and repeat.
Emphasis: Brace through your core at all times and try to keep your spine neutral throughout the duration of the movement. Do not let your knees push forward in front of your toes or cave inward on the movement.
Caution: Make sure you're in an appropriately safe environment for yourself and others and be sure the surface that you're throwing against is safe and sturdy.
Training Impact
Muscle Roles in medicine ball squat to overhead throw