I'm struggling with this anology because running a marathon and playing hockey are so different
But playing 24 mins a night isn't beyond a well conditioned athlete, and it appears Panarin understands how to pace himself shift to shift so he's not always running at 100%. The team doesn't play again until Wednesday so there's plenty of recovery time.
In other words.. If you're going balls out for 2 mins at a time (no such thing as pacing yourself unless you want to give up goals) , how are you going to have any energy toward the latter part of the game?
They're athletes not super heroes