John Isner, the top-ranked American on the men’s professional tennis tour, completed his return from a broken bone in his left foot by winning his fourth Hall of Fame Open singles championship on Sunday. He defeated 22-year-old Alexander Bublick of Kazakhstan, 7-6 (3), 6-3, on a stifling hot afternoon at the Newport Casino and became the first player to win the Hall of Fame title four times.

Oh, Isner is 34.

On Saturday, Leander Paes of India, who won the Hall of Fame championship way back in 1998, his only singles title on the ATP Tour, lost his doubles semifinal in three sets.

Paes is 46, the oldest doubles semifinalist in ATP history after John McEnroe, who was 47 when he reached the semis at San Jose in 2005.

Last week at Wimbledon, Novak Djokovic defeated Roger Federer in an epic final that went to an unprecedented fifth-set tiebreaker. The two future Hall of Famers battled for five hours with little separating victor from vanquished. They might still be playing had Wimbledon not changed its rules to call for a tiebreaker at 12-12 in the fifth.

Djokovic, the champ, is 32. Federer, the runner-up, will turn 38 on August 8. Thirty eight!

Are you catching my drift here? Tennis players at the highest level are playing well into their 30s, and beyond, and they are playing well. Serena Williams reached the women’s final at Wimbledon this month. She is 37. Rafael Nadal won his 12thFrench Open championship on June 9, six days after he turned 33.  Ivo Karlovic, the 2016 Hall of Fame champion, returned to Newport again last week at the ripe old age of 40. At the Maharashtra Open in India this year, he became the oldest finalist at an ATP Tour event since 43-year-old Ken Rosewall won in Hong Kong in 1977.  At Indian Wells, Karlovic became the first 40-year-old to win an ATP Tour singles match since Jimmy Connors in 1995.

How do they do it? Tennis players pay more attention to diet and fitness that ever before. Martina Navratilova pioneered cross-training in the 1980s as a means to improve her already formidable game and to avoid injury. She played her way into the Hall of Fame. Now, most players watch what they eat and hit the gym on a regular basis.

Advances in the treatment of injuries prolong careers. Athletic trainers have traveled the ATP and WTA tours for decades, but they have more tools and knowledge at their disposal.

Players at the top make so much money they can pick and choose their tournaments. A veteran like Serena Williams, who is a mother now and who has recovered from various injuries, can afford to focus on Grand Slam events. Federer has skipped the clay-court season leading to the French Open to prepare for the grass season and Wimbledon.

Thirty or 40 years ago, aging tennis players could look forward to various legends tours when they hit 35. They played before small crowds who remembered them in their prime in the days of tennis whites and wood racquets. Now, players approaching 35 can still win on the tour. Just ask John Isner.

Mike Szostak covered sports for The Providence Journal for 36 years until retiring in 2013. His career highlights included five Winter Olympics from Lake Placid to Nagano and 17 seasons covering the Boston...