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Lindsay Davenport believes she has survived to the ripe old age of 32 in tennis because she took two lengthy breaks from the stamina-sappping demands of the globe-trotting sport.

At 25, Justine Henin was world number one and dominated the sport. Many years of Grand Slam triumphs beckoned. But then she abruptly announced her retirement last month. The fire had gone.

Like her Belgian compatriot Kim Clijsters who quit the year before at 23, Henin was suffering from the scourge that threatens to decimate the sport — burnout.

Former Wimbledon champion Davenport, who pulled out of the tournament on Thursday with a right knee injury, said “There was definitely some times in my career where I’ve been burnt out.”

What gave her longevity was stepping off the treadmill.

“I’ve had two really long breaks and they’ve both really helped me tremendously kind of get the fire back burning,” the American player said.

But, in a bittersweet press conference where she hinted at retirement but still longed to compete at the Beijing Olympics and the U.S. Open, she waxed most eloquent when talking to reporters about the progress of her baby son.

“He’s almost walking. He’s very vocal … Yeah, he’s a love,” Davenport told reporters.

The players feel at times they are stretched to the limit by the demands of a glamorous sport that takes them round and round the world on an interminable merry-go-round.

Australian Open champion Maria Sharapova, knocked out of Wimbledon in a second round shock, feels the WTA, the sport’s ruling body, is ignorant of the players’ needs.

“Your voice is never being heard,” she complained.

World number two Rafael Nadal put it even more bluntly: “The calendar is impossible.”

Both the ATP, which rules men’s tennis, and the WTA have made plans to shorten the season from 2009.

The WTA is trimming the current 25 Tier I and II events down to 20 and WTA vice-president communications Andrew Walker stressed to Reuters at Wimbledon: “The health and well being of players is the number one priority.”

Keeeping a wary eye on teenage prodigies who could fall by the wayside, he said: “The tour’s eligibility rules that allow for graduated doses (of playing time) for younger players has resulted in an increase in player careers by 24 percent and a reduction in burnout to less than one percent.”

But from fashion shoots to endless media interviews, the players will inevitably face continuing pressures as the sport and its big business sponsors battle to give tennis maximum exposure on the world stage.