Quads, hamstrings, glutes primarily. Back secondarily.
Best in Workout:
Perform the barbell squat early in your workout. As it is a full-body move, it is best done with heavy weight,. Also it is tough on the lower back, so you want to be fresh as possible on each set.
Sets & Reps:
Performs 3-4 sets with 6-12 reps.
Space your feet shoulder-width apart and firmly plant them on the floor, then drop into a squat position. You need a firm foundation and it starts with your feet. If you are new to this move, or deadlift-type exercises in general, you might notice that your heels tend to rise off the floor at the start. Work to keep your feet flat, this will get easier as you warm-up and become more accustomed to the move.
With your arms fully extended, grasp the bar using a pronated grip just outside your legs, locking your thumbs around the bar. This position should resemble the start of a deadlift, only with the bar behind you. Many people make the mistake of trying to use their arms to pull the bar up. If you bend your arms in an attempt to raise the bar, you won’t be as nearly as strong as you could be. Your arms should act as hooks, attaching yourself to the bar.
Inhale deeply, holding your breath as you begin the move. You want to hold your breath at the start of the move. Not only are you stronger when you do so, but it will also increase your intra-abdominal pressure and stabilise your spine while protecting you from injury. As you begin the descent towards the start (bottom) of the move you will also naturally and necessarily hold your breath.
Drive through your heels, extending your hips and knees simultaneously until you are standing erect with the bar, exhaling at the top of the motion. At this point, the bar should be just under your glutes. The barbell hack squat is very similar to the deadlift, in that it is a pressing move for the legs. Again, if you try and pull the weight up with your upper body without concentrating on the legs, you will defeat the purpose of this exercise, not to mention risk injury. Remember to squeeze the quads, hams and glutes at the top as you catch your breath. Use pulling straps, since the amount of weight you can press with your legs will probably exceed how much weight you can hold in your hands.