Originally Posted by Jamie J. Skibicki
Can you expand on that last comment?
Yes. DUs are an advanced basic skill that should be practiced after mastering the basic bounce, alternating leg bounces, shuffles, skiers, bells, and single-leg bounces. DUs can have benefit in a rope training program when mixed in with other elements. CF likes them because they make people tired (from jumping 12" into the air and landing on their heels repeatedly).
I can come close to 180-190 rpm on alternating bounces when I'm jumping frequently. That's great for foot speed and quickness, but it has limited application for sprinting. DUs are even worse because you spend more time in the air. A good plyo and drilling program works better.
Like Jay said, the 20# med ball is stupid. There is rarely any benefit in going over 6 or 8#. If you pick up a ball over 10#, it should be an Atlas stone.