The Squat is a full body compound exercise. You Squat by bending your hips and knees while the bar rests on your upper-back. Squat down until your hips are below your knees. Keep your knees out and lower back neutral. Then Squat back up. Lock your hips and knees at the top. Squats work your whole body. Your legs bend and straighten to move the weight. Your abs and lower back muscles stabilize your trunk while your legs move. Your upper-back, shoulders and arms balance the bar on your back. Many muscles work at the same time, not just your legs. The Squat is the king of all exercises.