As much of a physical endurance as running a marathon is, being married to Tom Cruise and putting up with his constant crackpot sincerity is probably harder – so running the New York marathon was probably a cakewalk for Katie Holmes.

Yesterday morning, in a brief change of routine from making no good films ever and only being famous for implausibly getting married to a slightly odd man old enough to be her father, Katie Holmes ran the New York marathon. And Katie managed to complete most of the course incognito, too – that is until 15 miles in when Tom Cruise burst out from the crowd to plant a smacker on his wife's lips, blowing her cover wide open.

Well, it was either a kiss or Tom Cruise was informing Katie Holmes of the exact coordinates where he'd parked her wife-cage and the precise time that she'd be expected to crawl back into it. Hard to tell the difference sometimes, isn't it?

It says a lot that Katie Holmes is one of the most photographed women on the planet and yet she's able to run two-thirds of one of the world's most famous marathons without being spotted, as she did in New York yesterday morning before Tom Cruise jumped out of the crowd and snogged her in front of everyone.

Perhaps Katie Holmes managed this because of the mass community spirit that appears at an event like a marathon, and the sense of everyone clubbing together to achieve a common goal is something that overpowers the individual ego; perhaps it was because when you're looking at a thousand men huffing around in rhino suits, the sight of a lanky, mostly-anonymous woman in a baseball cap isn't all that spectacular; or perhaps it was because Katie Holmes is unidentifiable unless she's strapped to Tom Cruise's side with a look of panicked horror on her face. Truth is, we just don't know.

But who can blame Katie Holmes for trying to keep a low profile during the New York marathon? After all, what would people say to her if they knew who she was? "You were the only thing wrong with Batman Begins"? "Dawson's Creek was rubbish"? Anyway, near E 96th Street at the 15-mile point, Tom Cruise leapt out at Katie from the crowd with baby Suri in his arms and gave her a congratulatory kiss, presumably before retiring back to crowd to loudly exclaim how he just kissed a woman and he hoped that everyone saw it.

Tom Cruise was waiting at the marathon's finishing line, too, with another kiss to mark Katie's five and a half-hour completion time. After finishing the marathon, all Katie Holmes had to say to reporters was:

"I'm good, but I'm feeling very tired."

But, you know what? Good luck to Katie Holmes for achieving so much now that her movie career's pretty much completely dried up. Plus, marathon-running is a useful skill to have. Not only will the training increase her overall level of fitness, but it means that she'll also be able to run further away once she's spoon-dug her way out of the cellar that we like to imagine Tom Cruise keeps her in.