Setup
Place the barbell in the rack at the height of your upper chest.
If you don’t have spotters, make sure the safeties are set low enough that they do not make contact with the bar at the bottom of the rep but high enough to take the barbell off your back if you fail. Always test the height with an empty barbell.
Grip
The grip width for the squat should be as narrow as possible. The closer your hands are to your shoulders, the more your posterior deltoids “bunch up” and make a shelf for the bar to sit.
There are two grip options:
Thumbs on top
Place your hands on the bar with your thumbs on top.
Rotate your palms outward so that the knuckles of your thumbs point up at a 45-degree angle and your wrists are straight (i.e., aligned with the forearms with no bend or crease at the wrists).
Thumbs wrapped around
Take a grip with your thumbs wrapped around the bar.
Your wrists will be in an extended (bent) position when the bar is on your back. Make sure most of the weight of the barbell is supported on your back, not in your hands/wrists.
Bar placement
Place the bar low on your back, just below the spine of your scapulae.
This can be very uncomfortable if you have limited shoulder flexibility. Check out this video to learn a helpful shoulder stretch.
Stance
Unrack the bar and take two steps back.
Take a stance that places your heels about shoulder-width apart with your toes pointed out about 30 degrees.
Execution
Look down at the floor about one to three feet in front of your toes.
Take a deep breath and extend your upper back (puff your chest up). Hold your breath for the entire rep.
Start the descent by leaning over and reaching back with your hips while shoving your knees both forward and out (over your toes) at the same time.
Squat all the way down until your hip crease drops below the top of your kneecap. If you keep your knees shoved out hard, you will feel a stretch in your groin muscles (inner thigh) and a subtle bounce as you reach proper depth.
When you feel the bounce, initiate the ascent by driving your hips/butt straight up. Imagine the barbell is sitting on your lower back when you do this.
During the ascent, keep your back-angle constant. Do not allow your back angle to become more vertical or more horizontal by lifting or dropping your chest.
Lock your hips and knees out at the top of the rep, exhale, and repeat.
Tips
A wider grip will be more comfortable for lifters with limited shoulder flexibility. Start as wide as needed to get the bar in the right place on your back. With each warmup set, try to bring your hands a little closer. Over time, this will get easier.
To initiate the squat, think about pointing your nipples at the floor as you shove your thighs out of the way.
Focus on balancing the weight directly over the middle of your foot (right over the bow in your shoelaces) for the entire rep. You want to feel even pressure on the balls of the feet and the heels. If you notice the weight shift forward or backward during the movement, it’s wrong, and you should correct it on the following rep.
The most common mistakes in the squat are: 1) placing the barbell too high on your back, 2) not leaning over enough, 3) not shoving your knees out wide enough, and 4) not driving your hips up hard enough.
Your hips must lead you out of the bottom of the squat. When viewed from the side, your hips (not your shoulders) should move up first as you start the ascent.
Do not lift your head/chin at any point during the movement. Keep your head in a neutral position (imagine holding a tennis ball under your chin). Lifting your chin will cause you to raise your chest. Lifting your chest, in turn, will kill your hip drive and make the movement much harder.