[header] How to build muscle doing push ups [title] Make sure your form is correct. [step] When performing the push up, your lower back must be straight, i.e., not sagging or arching, and your feet must be shoulder width apart. Your elbows should be tucked close to your body, i.e., at a 20 to 40 degree angle from your abdomen. 
As you go down, make sure your chest gets as close to the floor as possible. [substeps] Make sure to tighten your abdomen, legs, and buttocks.