Pushups are generally prescribed as an exercise for working your chest, though your triceps and shoulders also play a role as ancillary muscle groups. What you may not realize, however, is that the pushup also works your back muscles. The muscles around your shoulder blades are called into play as stabilizing muscles.
Keeping It Regular
Regular pushups -- performed with your hands around shoulder-width apart, knees off the floor and torso braced tight -- target the whole of your back. The erector spinae muscles in your lower back act as antagonistic stabilizers to stop your hips from sagging. When performing pushups, keep your shoulder blades retracted, advises Zach Dechant, strength coach at Texas Christian University. This creates tension and stability across the rhomboid and trapezius muscles of your upper back.
An Unstable Approach
Taking your pushups off the ground and performing them on an unstable surface increases the amount of work your back muscles have to do. Try placing your hands on a stability ball when doing your pushups. Alternatively, Dechant recommends the medicine ball pushup, performed with one hand on the floor and one hand on a medicine ball, or pushups with your hands in gym rings.
Becoming a Renegade
The renegade row is an exercise that works your back muscles and core. You perform it by assuming a pushup position with each hand on a dumbbell, placed on the floor, then rowing each dumbbell up to your side in turn. Combine this with a pushup to make a chest and back combo exercise. Perform a pushup, then row your left arm up, another pushup, then row with your right arm -- that's one repetition.
Jump on the Pushup Band Wagon
Adding a band to your pushups not only increases the challenge, but forces you to keep your upper-back muscles tight. Place the ends of a resistance band under your hands so that it's looped over your back. Make sure there's a moderate amount of tension on the band when your arms are straight and descend as you would usually. Then, push back up forcefully. For an added challenge, strength coach Eric Cressey recommends performing these with your feet elevated too.