That's the claim from inside the Sheffield fighter’s camp ahead of the bitter rivals’ bout at Manchester Arena on February 19.
Khan, who hasn’t boxed for almost three years, has reportedly been sparring four-minute rounds, with just 30 seconds rest, and running for miles through the snowy Colorado mountains in America, where he is training.
Meanwhile, Brook has been based in sunny Fuerteventura since mid-December.
The 35-year-old told The Star: "Boxing is a young man’s game. Amir is the same age as me, you have got to listen to your body; recovery is as important as training hard in my eyes.
"If he wants to go out with a new trainer he doesn’t know, an old-school American trainer, let him do that. I think it’s an advantage to me.
"I personally think he’s got it wrong by doing that.”
Amer ‘Killa’ Khan – not to be confused with the Bolton fighter – will be in Brook’s corner next month.
He said: "I can’t even see Amir Khan going past six or seven rounds with Kell. I just think stylistically it’s all wrong for him with how he’s training.
"With Amir, he’s been to the moon and back. He’s got a lot of miles on the clock. He’s had a lot of personal problems, bad knockouts, whereas with Kell you can see he’s had a full front-end change with two new eyesockets.
"Kell has always been very robust and strong. I think that’s what it’s going to boil down to – that brute strength, that power will come through.
"Kell’s not had those bad knockouts when you are stretchered out, they put a lot of miles on the clock.”
Amir Khan is training under Brian ‘BoMac’ McIntyre alongside Terence Crawford, who has previously fought and stopped both him and Brook.
Brook’s last outing, in Novemeber 2020, was against the unbeaten WBO welterweight champion.
On his decision to train abroad in warmer temperatures, Brook said: “It’s absolutely baltic in Sheffield. It’s better for the body as I’m getting older.
"The air’s better, there’s not many cars on the road. There’s not many distractions here, everyone and their dog knows me in Sheffield.”