>>34675514A bunch of things anon. This is a static position not a dynamic movement. This requires large amounts of tendon strength. This requires a much weaker position to generate enough leverage to pull off. This has 2 points of contact not four. This has a greatly increased demand due to physics acting on the lever of your body to create a moment.
>>34675019In answer to your question OP, its not really something that has a direct translation. But generally from what a few gymnastics coaches have said a planche is equivalent strength to something like 2xbw bench in terms of raw strength, and bent arm strength doesn't translate well to straight arm. To get an idea of how difficult it is, go try and do a tuck planche. See how long you can hold it.