Lying Dumbbell Tricep Extension

Start by laying flat on a bench, grasp a dumbbell with both hands. Extend your arms upward, perpendicular to the floor, the palms of your hands facing your feet. Bend your elbows and lower the dumbbell behind your head until your forearms are beyond perpendicular to the floor. Without moving your upper arms, extend your forearms back to the starting position. Squeeze your tricep muscles at the top.