The shows one of the possible leveraging feats that can be done with a sledgehammer. This one involves lowering the weight to the nose then pulling it back up. Always a crowd pleaser, because it involves the danger element. If you were to not have the strength, the hammer would come down hard. (Some do the same feat but with an axe to amplify this danger!)
And on video:
Other levering feats include raising the hammer from the ground to an upright position or just holding it out straight from the end in front of you or behind.
All these moves involve the hand movements called ulnar and radial deviation. That is bending the hand from side to side, an oft neglected degree of movement and strengthening that is important for many feats like bending steel. In addition, you need a strong grip to hold onto the handle.
Slim ‘The Hammerman’ Farman is by far the strongest in all these moves, hence the nick-name. His records are likely never to be broken. Here’s a small clip of him in action.
In his setup for this, you can see he has developed unique methods of anchoring and state control around being the best performer ever at these feats.
These moves are very different from the swinging of a sledgehammer, like against a tire. While the latter is a great workout, it doesn’t make for a great show of strength. However, it is important to note that Slim developed much of his strength from actually breaking rocks with sledgehammers in a quarry for many years.
This can be done in a wide variety of different ways, and is used primarily for its conditioning effects, as is shown as exercise #2 in the following video: