Great-gran swimming to victory - at 91

Kath Johnstone has an exercise routine that would have people half her age panting. Photo / Paul Estcourt

Kath Johnstone has always been a swimmer, but it wasn't until her seventies that she started taking it seriously. Really seriously.

The 91-year-old great-grandmother has been competing in masters' competitions for the past 15 years, winning a number of gold medals.

And this year she is heading to Sydney to compete again.

The October World Masters' Games in Sydney will see her contesting freestyle events over 800m, 400m, 200m and 100m distances.

She is also set to take part in the 400m and 200m breast stroke, and will top off the competition with a relay.

Mrs Johnstone, a retired nurse, says she got back into competitive swimming after getting "p***** off at having to be 70". She entered her first masters competition at age 74.

Freestyle is her preferred stroke, though she has been known to dabble in breaststroke and backstroke.

She is no fan of the butterfly, however. "I tried it once and got half way along the 35m pool and I had to come up and ask someone how to breathe under the water."

Mrs Johnstone will team up with four others in Sydney, three of whom are the same age, and one who is aged 98 and blind. The blind woman starts the race for the team. She estimates when she is reaching the end of her length by singing a song as she swims.

Mrs Johnstone began swimming in Dargaville as a teenager, but in the following decades has played tennis, hockey and croquet.

She keeps a strict training regime. "I get up in the morning and I put my leg up as far as it will go - 100 times, in groups of 20. After that, I start bringing up my knee as far as it will go."

Then, after a number of stretching exercises, Mrs Johnstone hops on to an exercise bike for "one kilometre, every day".