At the end of the 5/3/1 book by Wendler, he throws a bit in there about conditioning after the sessions. Basically he recommended either hill sprints or Prowler pushes/sprints after each session.
"And for crying out loud. Don't go into the pain cave. I can't stress this enough. Your Totem Animal won't be in there to help you. You'll be on your own. The Pain Cave is for cowards.
Pain is your companion, don't go hide from it."