Hammer Time

Grip a 16-pound sledgehammer with left hand by base of handle and right hand halfway up. With knees bent, swing hammer above right shoulder and down onto a 300-pound tire with a steady rhythm. 100 reps.

Hackleman: "I call this the Earnie Shavers [after the boxer]—he told me about this drill. It's for punching power, and [Shavers] was one of the hardest punchers. The motion simulates an overhand right, the most common punch for knockouts. It's mainly for shoulder strength, but the core also gets worked.