That's called humour, it's not related to sport or to the bitcoin price itself, only people who call it "nonsense" can't get the humour.
But that text/phrase, idk if its actual said by satoshi to Sirius (Martini) in an email conversation publicized by Martini, check
https://mmalmi.github.io/satoshi/I assume the screenshot you posted is just an edited one. The bold text looks edited. But even if it's not edited, I don't think Satoshi ever said something like that. I will be happy if I get proved wrong.
The image has been edited. In the link where Martini's emails are found, email #129 does not say anything like that. And nowhere does the term “push-ups” appear...
I checked the link and based on the screenshot's date it should be "Email #1" in Martini's page, the rest are edited. So yeah, it's just a joke and as i said, it's all about the humor as there's no connection about it on btc price lol.
The thread just continued for several pages due to price speculation with the edited screenshot taken from Satoshi's convo with Sirius which is the interesting part.