The muscle-up [video] is no more than surmounting an object from which you are hanging or passing through an overhead egress - both functional and potentially lifesaving. The move is low skill, very low skill, yet possesses enough technical challenge that few people are able to perform it even when possessing the requisite contractile force. The modern trend of "dumbing down" PT, i.e. deliberately removing skill components, reduces strength (the productive application of force), blunts power, and retards speed.
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