Lying Dumbbell Tricep Extension (Skull Crusher) What muscles do Lying Dumbbell Tricep Extensions (Skull Crusher) work? The Lying Dumbbell Tricep Extension (Skull Crusher) is an isolation exercise that primary targets your triceps. It’s a strength exercise that uses push force. How to do the Lying Dumbbell Tricep Extension (Skull Crusher) Benefits of the Lying Dumbbell Tricep Extension (Skull Crusher) Tips for performing the Lying Dumbbell Tricep Extension (Skull Crusher) What equipment is needed to perform Lying Dumbbell Tricep Extensions (Skull Crusher)? What type of exercise is the Lying Dumbbell Tricep Extension (Skull Crusher)? How many reps you should do for Lying Dumbbell Tricep Extension (Skull Crusher)?