Why do CrossFitter do kipping pull ups?

Not a single day passes at the internet without anyone posting "funny videos" from CrossFitter doing kipping pull ups. People looking from an outside perspective on CrossFit find this funny, weird, if not disturbing. At least they don't understand. But here is the reason:
 
The CrossFit methodology trains our fitness in different categories of physical skills, 10 to be precise. The classic pull up focuses pretty much on the development of strength only. It trains the arms and the upper back especially. But when it comes to the generation of other skills such as power, speed and stamina, to the increase of output and efficiency, the kipping or butterly pull up is the superior choice.
 
In CrossFit, we vary our training between skill and strength sessions and competitive settings asking for finishing a physical task as fast as possible. While in first case we perform the regular, so called "strict pull ups" (even thought some people might not believe this!), during a time orientated WOD the kipping or butterfly pull up is the way to go. There are WOD's existing which contain up to 100 pull ups, in combination with various other exercises. Even
the strongest athlete couldn't handle this using the strict version. But look at the below posted video: The butterfly pull up enables you to perform an impressive amount of unbroken reps.

By involving the whole body and the explosive hip power especially, we are turning the pull ups from a strength towards a condition orientated movement. By involving not only the small biceps and lats, but several other massive muscle groups, we can increase workload while lowering fatigue. But notice: Without a basic strength - which means being able to do several unbroken strict pull ups - you shouldn't attempt the kipping pull ups versions. And also, it is not as easy as it looks. Especially learning the butterfly requires a good sense for rhythm and power generation from the core. But - it pays of.

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