The British number one revealed the sport's stars were likely to discuss the possibility of strike action at a meeting in Shanghai next month.
The threat has been criticised by some, but Navratilova, winner of 18 grand slam singles titles, believes the likes of Murray, Rafael Nadal, Novak Djokovic and Roger Federer would be right to flex their muscles should the powers that be not listen to their concerns.
She told BBC Radio 5 Live: "Of course tennis players want to play - that's what you train for.
"But if you feel you don't have control over how that's put together...
"If it's the only way they can get to that point, that's what they have to do - if they can unify themselves enough and if that's the last resort."
She went on: "I was complaining about the calendar being too long 25 years ago. We have shortened it on the women's side - I think the women play about a month less than the guys.
"But now, especially with Davis Cup, for Nadal or Djokovic or Federer the schedule is just untenable.
"Even Andy Murray - he does play Davis Cup but they (Great Britain) don't get that far - you cannot maintain that level of intensity and not put your body in hospital eventually."
With her doubles commitments, few players played more than Navratilova in her pomp.
But she feels the game is more punishing now than it ever has been.
"Nowadays the players travel much more than we did," she said.
"The schedule is more spread out over the whole world.
"They're playing on hard surfaces, with metal rackets, everybody hits the ball harder, it's definitely more taxing on the body.
"When someone in as unbelievable shape as Nadal runs out of gas at the US Open, it's too much.
"You only have one body, one career, you want to make the most of it. I don't see why Andy Murray should be criticised for taking control of his life."
Navratilova feels a strike by the world's top players would force the hand of the authorities.
"Without the top players, you really don't have anything and if they band together like that then the powers that be have to talk to them and listen to them," she said.
"They have been complaining about the long schedule for a long, long time and nothing has happened. The schedule is just as long.
"We're the only sport that does not have an off season.
"For the guys who are still playing in December, or even without the Davis Cup, they have about four weeks, then they start up in January.
"It's crazy, You can't do that year after year after year. It's going to take its toll which means you're career is going to be shorter, you're not going to play as well, you're going to be injured. Nobody wins in that scenario."