Think of this exercise as a push-up that's mostly for your shoulders instead of your chest. It forces the shoulders to work hard to drive your body back using a natural arc and push angle.
The Push-Back Push-Up
Level 1: Drop down, explode straight back, and return to push-up position.
Level 2: Same basic movement, but put your feet up on a braced bench. Your abs will be screaming.
A cadre of coaches discuss various bodybuilding and powerlifting topics, including the wisdom of trying to build size and strength at the same time, and the relative benefits of isolation movements vs. compound movements.