I mean, did a knight think "I should stretch before this fight so I'm more flexible and I don't hurt my muscles"?
Just wondered about it while I took a jog yesterday and thought it couldn't hurt to ask.
Can we extend this and ask about medieval fitness practice in general?
I wrote up an answer to a similar question a while back. Hopefully you find it useful. https://www.reddit.com/r/AskHistorians/comments/74w08y/did_knights_or_other_medieval_armies_stretch_or/do2bgdk