LONDON The evidence, such as it is, isn't what you would really call cast-iron, but let's not be churlish, because what we are looking at here could be nothing less than a whole new dimension to the hitherto deeply predictable male midlife crisis a sudden and unexpected concern with health.

Traditionally, of course, men have eased the existential angst that afflicts them between, say, 35 and 50 by driving small but potent sports cars, sitting astride large and throbbing motorbikes, or running off with younger women who haven't yet seen them at 3am when they get up for a pee and forget momentarily to suck their stomachs in.

Now, according to the retail analyst Mintel, they are buying top-of-the-range racing bikes instead, with the biggest growth in cycle sales this year coming from 35- to 45-year-old family men treating themselves to premium road bikes (as well, regrettably, as the eye-watering Lycra shorts, figure-hugging racing jerseys and special shoes that go with them). It is, the report proclaims, “the 'noughties' version of the midlife crisis”.

And if it's not a newfound passion for cycling, it's a sudden urge to run a marathon. A survey of 2,000 middle-aged men in July (by, oddly, the winemaker Redwood Creek) found that half of them had set themselves a daunting physical challenge in the last year, from distance running to mountain climbing and even walking the Great Wall of China. And while more than half - deluded fools - insist it's only about losing weight, 10 per cent admit that it's all down to “the midlife crisis”.

It is worth mentioning, at this point, that many experts doubt the existence of a male midlife crisis at all (or at least, they recognise that something sometimes happens to males in midlife, but won't call it a crisis). A 1999 study of 8,000 US men by the respected MacArthur Foundation found that while all were familiar with the term, only 23pc reckoned they'd had something resembling a midlife crisis, and only 8pc saw it as linked to the realisation that they were ageing.

“There is no handier excuse for human misbehaviour than the midlife crisis,” says Richard Friedman, professor of psychiatry at America's Weill Cornell Medical College. Of course, he wrote in the New York Times, middle age has its challenges first signs of physical decline, gnawing questions about personal and professional accomplishment. But all too often the classic responses - buy fast car, change job, dump wife - are more of a selfish “search for novelty and thrill than for self-knowledge”, Friedman says. “But you have to admit, 'I'm having a midlife crisis' sounds a lot better than 'I'm a narcissistic jerk having a meltdown.'”

Still, if the net result of this crisis-or-meltdown is that a generation of middle-aged men start living healthier lives, who cares? Men, as we all know, neglect their bodies something rotten; it is one of the reasons women, for no biological reason, live five years longer. “Better that a midlife male buys a mountain bike than a Porsche; better that he runs a marathon than runs off with the babysitter,” says Jim Pollard, author of the award-winning User's Guide to the Male Body and editor of the website malehealth.co.uk, who has written extensively on the male midlife crisis (although he, too, won't dignify it with that name).

“If that's the response to whatever it is that happens to men in midlife, then it's all to the good,” Pollard says. “It could reflect the fact that more blokes are recognising this for what it is - looking their mortality in the face, and deciding to try and postpone it for as long as they can - rather than just trying to be 21 again.” He is concerned, though, that the flash bikes mean that if this is a new trend, it is an affluent, middle-class one, that is not going to bridge the male health-wealth gap.—Dawn/The Guardian News Service