Roger Federer has opened up on his workout routine following his retirement from the sport last year.

20-time Grand Slam champion Federer retired from the sport in September last year after a hugely successful career which included 103 ATP titles and 310 weeks spent at World No. 1.

The Swiss tennis legend played his final matches as part of Team Europe at the Laver Cup in London, alongside Rafael Nadal, Novak Djokovic, and Andy Murray. Since then, Federer has been enjoying his new life spending more time with his family and exploring new hobbies while still keeping up some habits from his days on the ATP Tour.

In a recent interview with Tennis Channel, the 42-year-old revealed that he built an in-house gym just days after his last appearance as a professional tennis player. He was then jokingly asked about whether he would be able to compete with his longtime sporting rival Nadal in terms of biceps.

"What? No, no, no. He can have the biceps. I don’t need that one. I’ll never be there," he responded, laughing.

Federer then explained how he keeps fit through cardio workouts and core exercises, lauding the benefits of consistent exercise.

"I do everything – cardio, some weight training, more like, core exercises – a lot of that. It is also good for the back. I think, when you move less, your body hurts more. So, I think moving a bit is always good. It makes me feel better, for sure," he continued.

Federer was recently in attendance as a special guest at the ATP Rolex Shanghai Masters, where he received the first international "Icon Athlete" Award.