It struck me the other day while being miserable squatting that for all the talk and writing about how to squat, where to put the bar, how to program squats, there's a lack of talk on what to do before you squat. Maybe that's because I'm the only one who thinks it's worth talking about, but hopefully that's not the case.
Step one is to be prepared physically for your squats. This can apply to programming, i.e. don't be trying to do weights, reps, and sets you shouldn't be, but in this case I mean being prepared for the actual movement. Often squats are performed at or near the end of a workout, and if those workouts include things like snatching and cleaning, you're more than likely pretty warm. However, if you're squatting first or after exercises that don't include some kind of squatting motion, take the time to prepare.
Heavy squatting, especially for more than a single rep, is hard enough - when you add an element of discomfort or pain in the movement, your capacity will be limited whether you recognize it consciously or not. The ability to sit in completely and comfortably to the bottom of a squat will allow you to focus on positioning and applying effort to the fullest degree. Pain or discomfort will make you hesitant and invariably force you into different positions. When you're handling big weights, even very subtle shifts in position or your movement in or out of the bottom can cause a failed lift.
The full topic of warming up is beyond the scope of this discussion, but suffice to say you should be consistently doing some kind of thorough preparation work for all of your training. I've previously encouraged you to foam roll during this prep time, and this is particularly helpful when it comes to preparing for squats.
I like to start with my upper back and loosen up my T-spine, which, like in most people, is tighter and less mobile than it should be. If I'm really locked up, I may spend some time after several passes just lying back over the roller at different points and trying to let myself relax.
Next I will roll on my glutes, first with my legs straight out, moving across all aspects. Then I'll cross my leg over my other knee and hit all the hot spots in that lateral area that's typically troublesome. After this, I roll to each side and hit just the crest of my pelvis and around to the rectus femoris origin.
I'll then roll on the front of both my quads together. After a series of passes straight on, I'll rotate so I can hit the VMO of one leg and the lateral distal quad insertion of the other at the same time, and shift back and forth between legs. From here it's on to each quad alone, focusing in particular on the lateral aspects that tend to get extremely tight and chunky. I'm also sure to make long passes along the length of the quad up to top where I couldn't reach with both legs together. This is where I spend the most time.
Following the quad work, I will hit the hamstrings very briefly since they never give me much trouble, and then with one leg sitting near the end of the roller, I will spend some time on that adductor origin region, which I imagine looks much like the dangerous tangle of cables under my desk. This is usually the most painful area of the session.
Finally, I will hit the calves. This is an awkward region to roll and I don't spend as much time on it as I should simply because I get tired of holding myself up. However, rolling out the soleus in the 4-6 inches above the achilles tendon from back to side is immensely beneficial if you're anything like me and get serious lower leg pain from squatting if my ankles are too tight. This pain is one of the big limiters on sitting in to the proper bottom position of a squat.
Next, I have a stretch I always do no matter what else I do or don't do. With my feel well outside my normal squat stance, I lean down and grab the tops of my shoes at the ankles, wedge my elbows between my thighs, and sit my hips down slowly, pushing out against my thighs. Basically, I'm trying to push my femurs out away from my hips. This is very different from pushing your knees out. In this position, I will shift slowly from side to side and shift my hips up and down. After this I will sit in the squat position and stretch my ankles by keeping my foot flat on the floor and leaning my elbows on one knee, trying to close the ankle as much as possible.
When I'm feeling loose enough, I will grab a mini-band and wrap it around my legs just below the knees and perform a few slow squats, pushing out against the floor with my feet and against the band with my knees (don't push the knees out without pushing the feet out).
From here I'll finally get under the bar (an empty one) for a few squats. These tend to be slow and with pauses in the bottom with a bit of gentle bouncing for a bit more stretching. Depending on how I'm feeling, I may do a few sets with the empty bar or 50-70kg before starting my jumps up to my working weight.
Once you're actually squatting, there are still a few things to consider. While a squat doesn't have the technical elements of the snatch or clean & jerk, heavy sets definitely demand focus and mental preparation. Visualize your set being successful and powerful and generate the confidence you need. Quit talking with the people around you for at least a few moments before you get up for your set. Don't watch anyone else lifting.
Get chalk. With the bar on your back or shoulders, this seems odd, but if you're sweating, dry hands on the bar will make you feel more secure.
Slap your quads, your glutes and your lower back a few times (Use the backs of your fists on your back, or you can lean forward to get a real 2-hand slap on your lower back). I honestly can't tell you the mechanism behind this, but it works. And if it only works because you think it works, it still works.
Finally, be confident and forceful when you lift the bar out of the rack. This will have a significant effect on your confidence for the squat. If you unrack the bar meekly, it's going to feel extremely heavy and you're just going to set yourself up to begin doubting your ability to squat it. Instead, get a big breath, set your trunk solidly, plant yourself squarely and securely under the bar, and drive it up out of the rack without hesitation. Feeling the bar shoot up will remind you of your abilities and inspire the confidence you need.