Execution
Begin in a traditional push-up position with one foot positioned on top of the other heel. Slowly lower down maintaining a flat back (abs tight) until the upper arm is at or near parallel to the floor. 
Then press upward to fully extend the arms, and finish by protracting or rounding the shoulder blades at the top. Pause at the top, and then repeat.
Application
This exercise can be utilized for shoulder stability training, scapular strengthening and stabilization, core strengthening and general chest and shoulder strengthening. It targets the pectoral major/minor, deltoids and triceps, but I use it for specifically for advanced serratus anterior strengthening to resolve shoulder impingement.
Benefits include:
Improved shoulder proprioception
Optimal shoulder joint kinematics
Increased core strength and stability
Better shoulder stability
Reduced risk of shoulder impingement
Progression
To increase difficulty, you may choose one or a combination of the following:
Narrow the width of the hands to reduce the base of support
Brian Schiff, PT, CSCS (www.brianschiff.com) is a licensed physical therapist, respected author and fitness professional. He became a Certified Strength and Conditioning Specialist (CSCS) in 1998. In 2000, he opened his own personal training and sport specific conditioning facility, Fitness Edge, in Dublin, Ohio. Brian has presented at several professional conferences and seminars on injury prevention and sport-specific training.
