The intense nature of professional tennis circuits has a negative impact on players' mental wellbeing, according to Roger Federer.
The now-retired tennis great had a highly-successful 24-year career in the sport, but has now been able to reflect on the demands of the touring lifestyle.
Speaking at a Uniqlo press conference in Tokyo, the Swiss maestro underlined the link between tennis' intense schedule and the psychological challenges players face.
“You’re supposed to show strength. But we’re not machines, we’re human beings,” Federer said.
“When players retire at a super young age, I totally understand it.
“We see it from time to time. I always feel it’s such a pity because there could still be so much going on in the future.
“The tour is tough… travel, practice, jetlag.
“Nobody is allowed to say, ‘I’m tired today,’ because it looks like you’re weak, and that’s why players sometimes end up with mental problems.”
After signing off from competitive tennis at this year’s Laver Cup, Federer has noticed a significant drop in stress.
With four annual Grand Slam tournaments and ATP or WTA events on offer most weeks, tennis players tend to have short off-seasons as they aim to amass ranking points.
According to the 41-year-old, the professional circuit can be a never-ending cycle, which eventually takes a toll.
“As a tennis player, you’re always thinking about your next practice, your next match. It never lets you go,” he explained.
“Your next travel, your next packing … I don’t think I was that aware of it. That thought is always there and it rides with you until you retire.
“Then, you realise, that stress all drops away.”
On top of the demanding travel and ongoing timetable, Federer highlighted how strict doping measures also take their toll on athletes' stress levels.
“We have to fill out the doping forms every single day, one hour during the day, where(ever) you are,” he said.
“You’re always aware in the back of your head (that) they could be coming any moment, especially in that hour.”
Federer’s comments come almost a year on from the shock retirement of former world No. 1 Ash Barty, who announced she was walking away from the game just months after winning the Australian Open.
Despite her success at the time, the now 26-year-old made the surprise decision to retire, opting to step away and “chase other dreams”.
The Australian has since dismissed any suggestions that she could make a return to the tennis circuit.
“I’m done,” Barty said in November.
“You can never say never … but no.
“No, no, no. I’m done.”