Elitefts athlete and world-class lifter Chris Duffin revolutionized his shoulder health and upper body training when he invented the ShoulderRök. He has shown how he uses the ShouldeRök and discussed the purposes behind it and recently even began mass production of the ShouleRök for commercial purchase.
The idea behind the ShouldeRök is that, by swinging it overhead, a lifter is able to increase upper body mobility and health. Breakingmuscle.com provides a more detailed explanation:
Similarly, the ShouldeRök requires the reversal of the weight falling to the ground. When the weight hits the lowest point behind the back, it must be pulled up and around. It is the quick adjustment from relaxation to tension that sets elite athletes apart from amateurs. Great fighters are known to have quick switches between tension and relaxation. The kettlebell provides an analogy to the ballistics in jumping, the ShouldeRök provides an analogy to the ballistics of throwing.
This video is almost certainly a way to increase visibility (and, of course, sales) of Duffin's product, which is the expected response given the durability of the ShouldeRök and the extensive manufacturing process.
You can find more from Chris Duffin on his training log or via KabukiWarrior.com.
Video and header image via YouTube, Chris Duffin