To begin the push-up, start by getting on the ground in a plank position with your elbows fully locked out. Keep your body as straight as you can with your neck in a neutral position, bracing your abs and lower back as you begin the movement.
As you descend, make sure to keep your elbows tucked in close to your body.
Do NOT flare your elbows as it puts a lot of strain on the shoulder joints (as pictured). As you lower to the floor, do so in a slow and controlled fashion overloading the eccentric portion of the motion.
Bring yourself completely down, resting your chest on the ground. Once you have done this, explode back up to the top position, fully locking your elbows out at the top. Take a breath, bracing the abs, and restart the movement.