Skull crushers target the triceps using a barbell or dumbbells.
How-to: Lie on a bench with a barbell or a pair of dumbbells in your hands. Extend your arms straight above your chest. Bend your elbows and lower the weight towards your forehead, keeping your upper arms stationary. Extend your arms back to the starting position.
Focus: Maintain a controlled movement and keep your elbows in line with your wrists throughout the exercise.