In some ways, your body is a lazy bastard. it wants to do things the easiest way possible, even if it's not the best way. Take, for example, when you perform a squat. It's a demanding lift, and your body calls in numerous muscles to do it. That said, it can still sometimes skimp on a few-and that prevents you from lifting the heaviest loads possible. The solution: Get those lazy muscles to do their job.
HERE'S WHAT YOU DO
Lie facedown on the floor with your right knee bent 90 degrees so that your lower leg points straight up in the air . Now contract your glutes and drive your leg straight up into the air so that it comes off the ground (it's OK if you can't lift it very high) . Lower it to the ground, and-keeping your knee bent-rotate your lower leg 30 degrees to the left so that your foot lines up above your left knee. Raise it again . Lower your leg to the ground and, keeping the knee-bend, rotate it 60 degrees to the right. Raise it again , and then lower it to the floor. Now repeat all three positions on the left leg. (Note: Make sure your hips stay level with the floor at all times - don't let one hip rise up and turn as you raise your leg.) Chances are, both legs drifted out of position in at least one of those moves. Return your right leg to the position that gave you the most trouble, and squeeze your glutes again as much as you can without losing the position. Hold it for six to 10 seconds and repeat four to eight times. Do the same for the left leg. Now you're ready to squat.
Moving your legs through each position helps your central nervous system reestablish complete control over all the muscles in your glutes - major contributors to a big squat. As a result, you'll recruit more muscle and be able to lift heavier weights on your squat sets, as every muscle will now be pulling its own weight.