Why it’s on the list: Squats are king because they’re simply the most challenging leg movement you can do, especially when loaded appropriately. They work all the lower-body musculature (we’re counting glutes), and have been shown to spike muscle-building hormone release. In fact, we even know that squatting before doing curls has been shown to significantly improve arm strength!
We’ve grouped the high bar squat and low bar squat here, although they’re a bit different. Bodybuilders typically use the high bar squat, in which the bar rests atop the traps, which hits all the leg musculature fairly evenly. Powerlifters prefer the low version, in which the bar instead sits further down atop the rear delts, since this variation slightly shifts the body’s center of gravity such that the glutes take up more of the workload, which immediately allows the lifter to use more weight.