Lisa Markwell: I've got just the challenge for adrenalin junkies

'My thoughts and prayers go to James and his family... I'm sure he'll bounce back soon." Perhaps not the best choice of words for a man thrown from his bicycle and suffering a fractured skull, but it's the thought that counts.

Ben Fogle was commenting on the terrifying crash his erstwhile reality TV co-star (and erstwhile Olympic rower) James Cracknell suffered this week while pedalling 2,500 miles of Route 66. He was attempting to break an endurance record by running, cycling, rowing and swimming from Los Angeles to New York in 18 days. Like you do. It's not many days since Cracknell spent a week cycling from John O'Groats to Land's End. Both endeavours were in aid of charity, which is admirable. I suppose it's logical that the more extreme the pursuit, the more money gets raised. Why else would a sporting champion with plaudits and awards galore bother to be away from his young family?

In 2006 he left wife Beverley and their two-year-old son Croyde at home while he went off to row the Atlantic (with Fogle). Last year, when Beverley was eight months pregnant with daughter Kiki, Cracknell set off for the North Pole. He was, by all accounts, a little surprised and saddened to read at the time of his wife's distress in an article for The Daily Telegraph. But it hasn't stopped him. One might argue that Cracknell OBE, a national hero with a face for TV, could raise money appearing on panel shows, doing after-dinner speeches or – if all else fails – as a contestant on Strictly. All of the above would give him ample time for Mrs Cracknell and the nippers. But that's clearly not extreme enough. So what really drives these people?

The evidence points to a man trained to excel at sport, whose competitive edge has been honed to razor sharp. Just because he's no longer holding the oars on an Olympic lake, he doesn't stop wanting to feel the adrenalin coursing through his veins. James Cracknell should perhaps look at Steve Redgrave, who suffered multiple fractures only a month ago taking part in the world's toughest cycle race. Or what about Ranulph Fiennes, who has ended up hauling his sixtysomething ass up mountains because that's where the attention is, explorer-wise. Gnarly fingers are a small price to pay for the World's Greatest Living Adventurer (according to Guinness World Records). There must be ways of doing good other than putting your life at risk. Dicing with death – let's face it, frostbite or a fractured skull are no small injuries – is bonkers.

And no, this is not a "men, tsk" comment. Women can be hooked on pushing themselves too. Rebecca Romero switched from rowing to cycling (and won gold medals in both); last year she attempted to go from Land's End to John O'Groats on a tandem with, yes, James Cracknell, which sounds all kinds of wrong. They stopped on doctor's orders when Romero's knees were in danger of permanent damage. Back in the saddle, she told my colleague and ardent amateur cyclist Simon Usborne – while they both took part in that same length-of-Britain event as Cracknell last month – that she wasn't enjoying the cycling one little bit. Which sport she takes part in is irrelevant, she just chooses something she can excel at; achieving her goal is more important than having a good time. Adrenalin, it seems, is just as dangerous and addictive a drug as any Class A.

Get well soon, James, then get home and fit a child seat to your bike. That'll slow you down. I'll sponsor you to ride around Britain with Croyde, if you promise to make it last the entire school summer holiday. I feel sure that's a charity challenge Beverley could get behind.