CLEAN
Weightlifting movements are, in my opinion, the holy grail of power-based exercises. They allow you to move a lot of weight (force) fast (speed), making them the perfect exercises for optimizing power output (force x velocity). Unfortunately, barbell-based weightlifting techniques are extremely complex and require proper coaching and a ton of practice to perfect. For this reason, I recommend kettlebell and dumbbell-based variations of the clean and snatch for those of you who do not have access to proper coaching. With that said, here is how to properly execute a power clean.
STARTING POSITION: with your feet hip to shoulder width apart and your toes point forward or slightly out, position your hips so that your shoulders are just slightly out in front of the bar, with the bar over your mid foot and 1/2-1 inch away from your shins. You may have to play around with your hip height and torso angle to find the position that is best for you. Your back should be flat/neutral and your abs engaged. Grab the bar using a hook grip. That is, with your thumb wrapped around the bar first, with your other fingers over your thumb. Make a double chin and extend your neck so that you are looking forward up. FIX YOUR EYES ON ONE SPOT THROUGHOUT THE ENTIRE MOVEMENT! Loosen your arms and hold onto the bar with your lats and upper back (pull your shoulders back and turn your elbows/upper arms inward)
FIRST PULL - from the ground to your knee. Pull your shins back so that the bar can travel straight up (and not forward). During the first pull, your torso angle should not change much. Make sure to not pull your knees so far back that you create a ton of extra space between you and the bar. This part of the movement should be performed as fast as you can control.
SECOND PULL - From your knees to your upper thighs/hips. Aggressively pull the bar into your mid to upper thigh using your lats. Extend powerfully through your ankle, knee, and hip until your body forms a straight line from your ankle through your shoulder. You might extend through your lower back a little bit, but avoid hyperextension. Shrug your shoulders. You will have created enough power through your legs for the bar to float upward.
CATCH- while the bar is floating through the air, move your feet from hip to shoulder width apart (or slightly wider). Pull up on the barbell with your arms to drop your body downward underneath the bar. Drive your elbows upward towards the ceiling and begin rotating your hands around the bar. You should receive the bar on the front of your shoulders with your elbows up and in, your knees bent, and your torso upright (for the most part)
RECOVERY- Engage your leg muscles and stop the downward momentum of both the barbell and your body by pressing up against the bar. Drive upward and stand, keeping your elbows, eyes, and torso upright throughout.