Cornish Sharks boss Brian Smallworth says his side let themselves down physically as they lost 22-0 against South Wales Warriors.
The result means the Sharks miss out on place in the Division Two West end-of-season play-offs.
Smallworth told BBC Cornwall: "When it gets physical you've got to get physical and if you can't be physical then don't play the game
"This is a man's game, this isn't tiddlywinks," he added.
"It's the same with rugby," Smallworth continued. "You're going to get physical games and not physical games, but this is always a physical game and I love it but this is always how it is."
The Sharks end their season at the Newquay sport centre against Gloucester Banshees on 31 July.