Stand with your feet shoulder-width apart and extend both arms straight up overhead. Keeping your arms up and your chest tall, bend your knees and push your hips back into a half-depth squat - stopping before your thighs reach parallel - then drive back up to standing, arms still reaching for the ceiling. The overhead arms are the real work here: they force your back and core to hold you upright while your legs pump through the reps.

Works: quads, glutes, shoulders, upper back, core

Breathing: Inhale as you sink into the squat, exhale as you drive back up.

Common Mistakes: Letting the arms fall forward as the hips drop, rounding the upper back to keep the hands high, and letting the heels lift off the floor.

Make Easier: Bring your hands down to your hips or chest, and squat only as deep as you can keep your chest tall.

Make Harder: Slow the tempo and pause at the bottom of every rep, or go full depth with Squats or add flight with Jump Squats.