When it comes to exercise, it’s never too late, and it can change the dynamics of getting older.

I’ve driven through the coal-rich soils of Victoria’s Latrobe Valley, past the apocalyptic towers of Yallourn power station to Maffra, a dairy town set amid farm-studded flatlands that sweep in a panoramic rise up to the serried peaks of Australia’s Great Dividing Range.

This is Karla McKinlay country.

On the undulating bitumen of the Maffra backroads, the 72-year-old retired anaesthetist has honed a physique that allows her to do things many people 50 years her junior would find impossible. Last year she completed the Ironman World Championships in Kona, Hawaii. For the uninitiated, that’s a 3.8-kilometre swim and 180-kilometre bike ride, topped off with a marathon across the unforgiving windswept south-eastern tip of Oahu Island.

McKinlay greets me at the door of her modest house. She is elfin, clad in sports gear, and sprouts a shock of white hair above a steely gaze that reeks of determination. Across the kitchen table she gives clues to where all that grit comes from.

“When I was a kid I was always top of the class at school, but in sport, although I was sporty and I made the school team, I was never number one,” she says.

Our chitchat takes in an almanac of sporting achievement that would seem to have made up for the deficiency: 19 Ironman races since the age of 63; first Australian female over 70 to complete Kona; fastest time of 12 hours 54 minutes. To give perspective, that’s more than an hour faster than the time set by Australia’s younger, and famously fit former prime minister, Tony Abbott, in his debut ironman competition in 2010.

It’s a CV that looks firmly in the reserve of the freakish elite, and Kona may well be off the agenda for most older folk. But science is delivering a loud message to those who think getting old means an inevitable slide to decrepitude: the key to physical prowess may well lie in your hands, or legs.

Actually, let’s start with your head.

You can read my full cover story from the 2019 summer edition of Cosmos Magazine here