Located on the back of the upper arm, the triceps muscles are the powering forces behind the kind of dynamic arms swing that aid in getting you up hills, past “the wall,” and across finish lines.

If you've read our round-up of tricep exercises, you'll know that the tricep muscle makes up 60% of your upper arm. We know.

The name skull crushers isn’t too enticing—I get it—but it's a great triceps-toning move, and not as scary as it sounds. While it might be a little more advanced than other dumbbell exercises ...