The Camperdown triathlete yesterday left the door ajar for a return but conceded his days contesting the gruelling endurance sport were probably over.

His retirement, at age 40, came one day after he set a personal-best time for the 3.9-kilometre swim, 180-kilometre ride and 42.2-kilometre run.

He clocked nine hours, 21 minutes and 22 seconds in the Asia-Pacific Ironman Championships in Melbourne, earning him 15th in the men’s 40-44 years section.

McDonald, who is coached by Geelong-based Jarrod Evans, said he was rapt with the time, despite fading badly during the run leg from Frankston to St Kilda.

His splits were 54.56 for the swim, 4.45.20 for the ride and 3.35.48 for the run, plus 5.28 for his two transitions.

“I did a really good swim, around 54 minutes. I was out on the bike three minutes earlier than I wanted to be,” he said.

“We set some targets for the 90km point and the 180km point on the bike. I was under those. All was on track for a really good race.

“I had a really good first 10-15km on the run, even up to the 20km mark, and from there I started to fade more than I wanted to.

“If I had have run at the peak of my form we could’ve been talking about close to a nine-hour race but that’s racing. It’s what the day provided.”

McDonald, a father of two, said the result earned him the chance to compete at world championships for a fourth time in October this year.

But the plumber turned down the offer, opting instead to most likely end his ironman career on a high, although he will still race shorter-distance triathlons.

He has completed 16 ironmans over 11 years, competing in Melbourne, Port Macquarie, Forster-Tuncarry, Busselton, Hawaii and New Zealand.

At the peak of his training program, he was tallying 14 hours in the pool, 500km on the bike and 90km pounding the pavement weekly.

McDonald said a lack of motivation and family commitments factored into his decision. His body could handle another race but “I feel I’ve got nothing to prove in ironman circles”.

“For 11 years and 16 ironmans and countless other races I’ve done, it has been at times a little bit of a selfish sport, if that’s the right word,” he said.

“My wife Lisa and (sons) Kurt and Bailey, I couldn’t do it without them. They’ve been absolutely fantastic the whole time.

“There’s no regrets. You have some races that don’t turn out the way you want them to but it’s how you handle that situation and move on. It is what it is.”

McDonald was one of half-a-dozen athletes with south-west connections to contest the Asia-Pacific Ironman Championships in Melbourne.

His brother Martin McDonald finished in 10.32.52 and was 93rd in the men's 30-34 years section.

Rosebrook’s Stuart Reeve finished in 10.55.17 to finish 155th in the men’s 35-39 years section.

Warrnambool’s Michael Koutsoukis was home in 12.21.37 to place a credible 33rd in the men’s 55-59 years section.

Former Warrnambool couple Jason and Emma Cook, now of Darwin, returned to their home state to race.

Jason clocked 9.55.02 and was 65th in the men’s 35-39 years section and Emma clocked 12.07.19 to be 32nd in the women’s 35-39 years section.

Melbourne’s David Meredith, a Warrnambool Tri Club member, finished in 14.44.16 and was 348th in the men’s 40-44 years section.