Speedo scenes make a splash in 'Amphibians'

When the young theatre director Cressida Brown suggested I write a play that responded to her research into the careers of Olympic swimmers, my impulse was to pass. I'm a lifelong sport-phobe – the Olympics wash in and out my awareness, I can't string two words together about football, and nod off over cricket. Yet as I watched her with Olympian swimmers, retired and otherwise – Cassie Patten, Adrian Turner, Georgina Lee, Mike Fibbens and Mel Marshall – I found their stories compelling.

It was something to do with the odd shape their lives all shared – a kind of inversion of our normal lives where we muddle through to our twenties, making mistakes, and finding out what we're here for. Swimmers are set on course for their careers at the age of seven or eight and contemplate retirement in their twenties. In my, our world, success comes through a mixture of self-belief and approximation – but in the water, there is only performance, absolute, measured in points of seconds and earned through years of unstinting effort.

I came to think of swimmers as a race apart – as amphibians, half their lives immersed in 50-metre pools, entirely alone – as one commented, "there's only you and the black line". The questions that demanded dramatisation were: "How does this all begin, and what happens when it ends? After triumph or despair, neither of which admit any ambiguity, how do you return to the world of compromise and mediocrity we all inhabit – how do you get back on land?"

Amphibians examines those tensions and, at the heart of that, is the biggest challenge of all: how might a landlubber medium such as theatre engage with a life in or under water? I can only say I am delighted now I took a dive into this world.

'Amphibians', Bridewell Theatre, London EC4 to 28 January (020-7922 2922; www. offstage.org.uk)