How many push ups should you perform to build muscle? The short answer is as many good reps as possible per set.
To build muscle you need to place a combination of mechanical tension and metabolic stress on the targeted muscles. In the push up this is the chest, shoulders and arms.
The amount of mechanical tension experienced during a regular push up is determined by your bodyweight. Heavier people generate more mechanical tension, lighter people generate less mechanical tension. Outside of using a weighted vest or resistance band there is not much you can do to increase this variable during any given workout.
On the flip side you can readily manipulate the metabolic stress experienced during a set of push ups by using the following variables to your advantage.
Slower Rep Speed
Performing push ups at a much slower rep speed eliminates momentum and keeps more constant tension on your working muscles. Try it and see. Its hard work!
Eliminate Rest Positions
At the top of the push up your skeleton is supporting your bodyweight and your muscles are doing very little meaningful work. Avoid pausing in this position. Instead seamlessly pass through and begin your next rep. Again, easy to say but hard to do.
Momentary Muscular Failure
Importantly don’t stop your set when you start to feel slightly uncomfortable. Keep going. Perform each set to an extremely high degree of effort. Ideally to the point where you cannot, despite your best efforts, complete another repetition with good form.
Set a timer and start the set
Perform each rep at a slow controlled tempo
Pause at the bottom of each rep
Smoothly turnaround at the top of each rep (no pause)
Continue until, despite your best efforts, you stop moving
At this point continue pushing for another 5-10 seconds
Stop the timer, rest for a few minutes then repeat a second time
Good work. You have now applied the maximum possible stimulus for your muscles to grow. The rest will be dictated by the quality of your recovery (sleep, rest, nutrition), the consistency of your workouts, a determined pursuit of progress and your genetic potential for muscle growth.