The push-up is a classic chest exercise. While the chest is the main target in the standard push-up, it actually works just about all upper body muscles to some degree. This is an advanced version of the standard push-up. It is performed in the following manner:

First, place the resistance tubing behind your back and under your shoulders. Kneel down on the ground and place your hands shoulder width apart. Tighten the resistance tubing by placing your bodyweight on top of it. Your body should be suspended on four contact points: the toes of both feet and each arm. Next, ensure your back is perfectly straight, then slowly lower your upper body until the chest is a few inches from the ground (or until the elbows are 90 degrees). Slowly push up to the starting position and exhale as you push. Repeat the exercise.

Note: To add difficulty to this exercise, loop the resistance tube several times around your hands. The aim is to reduce the "slack" in the tubing line. This will ensure constant tension is being provided throughout the entire range of motion.