Carl Frampton has revealed how some of his old training and recovery methods left him "struggling to put my socks on".
The 35-year-old retired from the sport last year after winning world titles in two different weight divisions.
Frampton reached the pinnacle of boxing with his elite performances inside the ring.
Read more: Carl Frampton recalls opponent who left his body 'aching for days'
But he believes the sport is "behind the times" when it comes to preparation and recovery.
And he says some of the methods he used in his career left his body on the brink of breakdown.
Speaking ahead of Josh Warrington vs Kiko Martinez this weekend, Frampton told Radio 5 Live's Boxing with Steve Bunce show: "It is a sport that's behind the times in terms of strength and conditioning, even nutrition. It is a weight-making sport that is behind the times with nutrition. That's how silly boxing is at times.
"But all these things seem to come in behind other sports that are more advanced than we are. We have these old methods, that you have to be up at 5am and do hundreds of rounds of sparring.
"And in my opinion, you don't need it. Sparring is important, especially at the start of your career. But someone like Josh Warrington knows how to fight. He doesn't need too much of it."
Frampton added: "As I got older I used to struggle to put my socks on, and I was a so-called world class athlete getting ready for world title fights.
"And I was hurting putting my socks on, which is mental.
"I wish I had taken care of my body more and did more stretching and things like that."
Frampton recently admitted he considered making a comeback after watching former rival Martinez become a world champion again last year.
Martinez - who Frampton beat twice in his pro career - sensationally stopped Kid Galahad in November to claim the IBF World featherweight title.
Frampton brought the curtain down on a glittering career last April, but says he "briefly flirted" with the idea of returning to the ring after Martinez's win.
The former two-weight world champion told Belfast Live: "When Kiko won the world title and beat Kid Galahad, I went for a run the next day. But when it took me four days to recover from a 5-6k run I knew I don't have it anymore.
"So it quickly went out of my head. It was literally in my head for half a day, about potentially making a comeback.
"I am very happy with what I did in boxing. I couldn't get close to the levels I once was at, so no, not a chance."
He added: "I flirted with the idea, but very briefly. Literally for about 12 hours. But it was probably a silly thought, to be honest."
Read more: Jason Quigley picks his winner in Carl Frampton vs Michael Conlan mythical fight
Read more: Carl Frampton opens up on heated confrontation with John Fury
Sign up to our free sports newsletter to get the latest headlines to your inbox.
