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Annika Sorenstam, generally accepted as one of the finest golfers of the modern age, is retiring from the women's pro tour at age 37, although she carefully avoids using what she calls the "r-word." Justine Henin, the current No. 1 player in women's pro tennis, is retiring from the tour immediately at age 25, a decision she calls "definitive."

Aside from the shock value of having two top-tier female athletes hang it up in the span of 24 hours, what do the events have in common? Not just a truckload, actually. Sorenstam and Henin are at such different stages of their respective careers that any casual connection between them seems destined for the buffoonery pile.

But this much we know: It's a young person's game. Any game. And the real wonderment isn't that Henin cannot figure out a reason to go on at age 25, but that Sorenstam consistently did find so many reasons to want to play deep into her 30s. On almost every level, the pro athlete's life argues for a short story line. It's a fantastic upset almost every time anyone stretches it out.

Of the two announcements, Henin's has been received as the more surprising, and it has inspired the usual mixed bag of speculation: she's afraid to lose (false, although she had a couple of well publicized defaults over the years); she has health issues (obviously, since Henin has needed cortisone shots for her balky knee); she's pregnant (not gonna go there), and so on.

But Henin's own words argue more powerfully than the speculation. After losing at the German Open last week, the latest in a series of subpar performances, Henin said she "decided to stop fooling myself and accept it."

Hardly a scandalous conclusion: Burned out, hobbled by injury and clearly not the player she was even a year ago, Henin ran out of inspiration. It isn't fatal; often, it isn't even forever. What it is, is common.

Bjorn Borg retired at age 26 (we'll pretend his awful "comeback" years later never happened). John McEnroe played years beyond that age, and played well, but people tend to forget that McEnroe had been a pro for only eight years when he needed a six-month break in 1986. The next year, McEnroe took seven months off.

Kim Clijsters' pro tennis accomplishments do not approach Henin's in terms of championships, but Clijsters' retirement last year at age 23 sounded a familiar tone. Clijsters started a family. As Henin put it in her news conference Wednesday in Belgium, "It is my life as a woman that starts now."

It is, indeed, a young person's game. The stars of many sports who defy the odds and play late into their useful careers often obscure the fact that the "field" -- in golf, in tennis, certainly in baseball, basketball, football and hockey -- is largely filled with a rotating cast of very young players, most of whom don't last long enough to ever contemplate such an exotic thing as retirement. Far more often, the decision is made for them.

Burnout is real, and especially so in the individual sports in which one's performance week to week drives income. The fact that Henin won $5 million in 2007 alone doesn't speak to the forces she had to summon to do it.

Sorenstam probably can relate. Though at age 37 she's 12 years Henin's senior, the golfer's desire to throw herself into a new marriage and family while expanding her brand to golf course design and academy sounds like a genuine reason to go. And when she says, "If I can't have it 100 percent, then I don't want to give any," Sorenstam is saying that the only way to play top-level sport is to put everything else in life second -- or third. As soon as any other thing begins creeping up the list, your days as a champion are numbered.

(By the way: If you haven't started appreciating Tiger Woods circa '08, now would be a good time. Through marriage, family, loss of loved ones and, recently, injury, Woods remains an almost implacable winner. Thank goodness he isn't human; it might be intimidating for the other guys.)

Fans and aficionados are, of course, poorer for Sorenstam's decision -- although she'll achieve a coronation of sorts with her farewell tour the rest of the year. She has returned from neck and back injuries and risen to the No. 2 spot, behind Lorena Ochoa, a wonderful accomplishment and one fitting to Sorenstam's career. But she won't catch Ochoa. Ochoa is 26 and literally striding into her prime.

Golf isn't tennis, a sport where many great players are already in their primes at age 21 or 22 and can actually be on the downhill side at 25. And Henin isn't Sorenstam, who came to international prominence in her sport somewhat later in life, and whose 10 major championships (her first came at age 24) and utter domination of the field for years on end elevated her to a sort of sacred position within golf's ranks.

But retirement comes when it comes in sports, at times and at ages that simply don't translate into any other sector of our world. However curious the decisions or the timing, it's hard to argue that either woman didn't earn her way out into the rest of her life.

Mark Kreidler is a regular contributor to ESPN.com, Kreidler can be reached at mark@markkreidler.com. His book "Six Good Innings", about the pressure-filled season of one Little League team intent on upholding its town's championship tradition, will be released on July 1. His book "Four Days to Glory" has been optioned for film/TV development by ESPN Original Entertainment.