Body-weight exercises, which use only the weight of your body for resistance, provide a convenient way to train when you cannot get to the gym. Pushups are an effective body-weight exercise. Triangle or diamond pushups are a difficult pushup variation that requires a great deal of upper-body strength. Check with your doctor prior to attempting triangle pushups.
The triangle pushup gets its name from the positioning of your hands. Kneel on the ground to get your hand placement right. You may want to master this pushup in a modified position, keeping your knees on the ground, before attempting it with your legs straightened out. Place your hands directly under your breast bone with your elbows pointing back toward your feet. Make the shape of a triangle with your index fingers and thumbs. With your torso completely straight, lower your body toward the ground, bending your elbows back and alongside your torso. Push back up until your arms are straight.
Triangle pushups are effective at isolating your triceps brachii muscles, which run along the back side of your upper arm. Your triceps connects your shoulder blade and your upper arm bone to your elbow. This is the muscle that helps you push with your arm. Because your elbows point backward in a triangle pushup, this pushup targets your triceps as you push your body back up until your arms are straight.
Your chest muscles also get a good workout from a triangle pushup. The bigger of the two muscles in your chest, your pectoralis major connects your collarbone, breastbone and ribs to your humerus, or upper arm bone. Your pectoralis major muscles help with the pushing movements of your arms. A triangle pushup activates your chest muscles as you push back up into the starting position.
The final muscle you use in a triangle pushup is the serratus anterior. This muscle connects from your top nine ribs to your shoulder blade, which it helps move forward. It is located under your arm on the side of your ribcage. As you perform triangle pushups, the movement required from your shoulder blade works your serratus anterior.