To setup for the tricep pushup place your feet together and your hands flat on the floor with your thumbs facing inwards and almost touching (see picture number 1). Your body must remain straight (like a board) throughout the entire set. To keep your body straight squeeze your mid section tight. Now, keeping your elbows tucked in at your sides slowly lower your body down until you're about 2 inches from the floor. Pause, then push your body back up to the starting position. Repeat for desird reps.
source: www.etricep.com
