Swiss tennis star Roger Federer has described how he’s body reacts compared to when he was younger.

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The 40-year-old is currently sidelined for the remainder of the year after undergoing knee surgery.

It’s Federer’s third knee surgery in the past 18 months but the 20-time Grand Slam champion is eyeing a return to the sport in 2022.

Things aren’t the same though when compared to Federer’s heyday when he was raking in major titles.

In an interview with GQ, Federer responded when probed on how his body is responding differently now that he’s older.

“I think it’s a really good question and probably every active 40-year-old will answer it a bit differently because we all come with our own luggage or injuries or issues to that point,” he said.

“I used to have a lot of back problems, but these kind of went away because I was able to fix those, you know, but then, naturally, you have other issues as they come about. I think the biggest difference for me that I feel is that when you are 20 and you have a back issue, a couple of good sleeps and it’s done, it’s gone. Not so much now! Nowadays, the pain can last for days, weeks or longer. And this slows you down in terms of how many tournaments [you can play].”

Nearing the twilight of his career, Federer said he’s needed to “become stricter” in training.

“Maybe you need to pick what you do: the jumps or the running, but not both at the same time as you once did. You need to listen to your body more, take notice of the signs. Essentially, when you are 20 you just do everything all the time without having to think; at 40 you need to be smarter. I actually enjoy strategizing it all nowadays.”

Picture: Roger Federer – Laver Cup/Twitter