‘Do You Want a Player to Die?’ Tennis Feels the Heat Over Extreme Conditions.

Novak Djokovic lies on the court during a match against Jaume Munar at the Shanghai Masters.Holger Rune, one of the world’s best tennis players, was in Shanghai this month, sitting on court in a puddle of his own sweat, when he turned to the chair umpire in bewilderment.

PREMIUM ‘Do You Want a Player to Die?’ Tennis Feels the Heat Over Extreme Conditions.

“Do you want a player to die on court?” he asked.

Exhausted and exasperated, Rune couldn’t believe that he was being made to play in such suffocating conditions. The temperature was around 93 degrees and the ambient humidity was somewhere between Nordic sauna and Brazilian rainforest. But for the past two weeks, that’s exactly what the game’s top men and women have been up against during their late-season swing through China.

“We can handle a certain amount of heat because, you know, we are fit, we’re strong, we’re mentally strong as well, but there’s always a limit,” said Rune, the world No. 11 from Norway.

The heat is familiar enough to players who spend their seasons chasing the sun. It’s the humidity, which has spiked to over 80%, that has them feeling ready to keel over between sets. At the current Shanghai Masters tournament, which runs until Sunday, Novak Djokovic threw up in the middle of one match and world No. 2 Jannik Sinner had to abandon his third-round contest and be helped off the court. Australia’s Alex De Minaur said he is sweating through four pairs of sneakers every time he plays.

Five hundred miles inland, at the women’s Wuhan Open, conditions are just as challenging, with some players limping through the rounds on the verge of collapse.

“I hope the other matches will be scheduled at a time where girls can compete, rather than just die on the court,” six-time major champion Iga Swiatek said.

The complaints this week aren’t entirely new. Extreme conditions are now a recurring problem in tennis, from Melbourne to Cincinnati to the Middle East. But they have taken extra urgency among players who are actively lobbying for more control over their grueling schedule and working environment. Top pros need to spend 11 months of the year on a constant hunt for ranking points and prize money, which they say leaves them without adequate time to recover and at risk of injury.

Jannik Sinner received medical attention before retiring due to an injury in Shanghai.

The Association of Tennis Professionals, which oversees the men’s tour, said this week that it would review its rules for extreme heat. Grand Slam tournaments and the WTA, which governs the women’s tour, already have provisions for extended breaks and even match suspension when temperatures exceed around 86 degrees Fahrenheit.

“It’s crazy humid, to be honest,” Djokovic said. “I don’t remember the last time I played in humidity like this. It is what it is, you know, it’s the same for me, my opponent, and every other player. You just have to accept it, deal with it. A lot of sweating. The laundry bills will be quite high this week.”

Write to Joshua Robinson at Joshua.Robinson@wsj.com

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