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.