The difference between Roger Federer's 2017 and 2021 comebacks is that now his muscles have deteriorated considerably: Pierre Paganini

Roger Federer’s long-time fitness trainer Pierre Paganini recently provided some updates about the Swiss star’s recovery process. Paganini highlighted the fact that Federer's muscles have become weaker with age, but lavished special praise for the 39-year-old's perseverance.

After 13 months on the sidelines, Roger Federer will be making his comeback to the tour at next month’s Qatar Open. During his time away from the sport, the Swiss legend underwent two surgeries on his right knee and followed that up with a lengthy rehabilitation process under the watchful eyes of Pierre Paganini - who has been training him for 21 years now.

While speaking with Rene Stauffer, Paganini made a startling revelation, explaining how Federer’s body has suffered significant degradation during this period - which is in sharp contrast to its condition during his 2016 injury hiatus.

"The big difference (between 2017 comeback and now) is, as he paused until Australia after Wimbledon in 2016, his muscles were actually always there," Paganini said. "Now we had a total interruption and the muscles deteriorated considerably."

Roger Federer came back from injury in 2016 and lifted two Majors in 2017, leading many to be hopeful of a similar output this time. Paganini hasn't ruled out that possibility, but his words suggest the task will be substantially more difficult for Federer this time.

Nevertheless, Paganini did assert that Federer’s recovery process was driven by his willingness to keep fighting hard. According to the 62-year-old, Federer's love for the game has been instrumental during this period as it has enabled him to carry out fitness drills that require a lot of patience.

"Without Federer's patience, the guillotine would have fallen long ago," Paganini added. "He depends on it (passion), and so do we! When a player who's almost 40 has to do exercises that a 70-year-old can do without any problems, and is happy that it gets better every day - if that's not passion (then what is)."

Paganini further revealed that Roger Federer’s participation at the Dubai Open is not yet a guarantee, as was previously believed to be.

"At the moment it is only clear that he is playing Doha, then we'll see," Paganini revealed.

The right knee had been causing Roger Federer problems for several years: Pierre Paganini

According to Pierre Paganini, Federer’s right knee had been bothering him for a long time but was largely 'under control'.

"The right knee had been causing him problems for several years," Paganini said. "But he had them under control, with adapted planning and specific exercises."

Federer’s fitness trainer also provided an update on the player’s physical condition, revealing that Federer had regained his muscle strength and was training without any hiccups. Paganini added that Federer was currently working hard to regain his speed - the base of his world-class footwork.

"In the strength area back to where it was before the injury," Paganini said. "He actually trains almost normally. If you were to watch you would say: he is not hurt, everything is fine."

"There is absolutely nothing to hide here," he added. "We are working hard on his speed because we know very well that this will be an important point."

Roger Federer will never risk his health: Pierre Paganini

Pierre Paganini aired a word of caution about Roger Federer’s time left on tour, stressing that the Swiss star would quit if his body started betraying him too often.

According to Paganini, Federer always makes his decisions keeping one eye on the future. That, the 62-year-old believes, is why Federer is never inclined towards risky moves.

"He will never risk his health," Paganini said. "It is extremely important to him to be healthy in the second phase of his life. He won't overdo anything if it doesn't make sense. He's very strategic and farsighted."

Pierre Paganini went on to speak in glowing terms about Roger Federer's nature, which he believes is an important reason behind the Swiss star’s widespread popularity.

"The fact that he is highly esteemed by his fans is not only down to the player but also to the human being," Paganini said. "And he will always be this human being as long as he lives."