HOW: Start by lying on your back on a bench with a dumbbell in each hand. Bring the dumbbells up at chest level. Hold them with your palms facing each other. Squeeze your elbows in (pretend like you are trying to hold a ball with your elbows) and bend at the elbow lowering the dumbbells down next to your head. At the bottom your elbows should be pointed straight up. Bring the dumbbells back up to the starting position and repeat.
FEEL: You should feel your triceps muscle working.
COMPENSATION: Make sure to start with your arms straight up from your shoulder, not behind. Keep your elbows in, don’t let them come out.