Perfect Your Technique Triceps Prone 15 May 2017 Studio Pilates Not just a tricep exercise! Triceps prone brings your buttocks, back and the backs of arms into play. Keep the shoulders drawn down and away to work the midback muscles. Keep the elbows pinned close to the sides of the body to engage the triceps. Aim to find a full extension in the arms to sculpt and strengthen the backs of your arms.