Portland's Lachie Johnson, 17, was the first male home and Warrnambool's Jenny Dowie the first female across the finish line after navigating a 500-metre swim, 20-kilometre ride and 5km run.

Johnson swapped his motocross bike for running shoes during the COVID-19 pandemic.

He'd completed triathlons in the past, having followed dad Adrian into the sport, but opted to commit to a full season in 2021-22.

The Portland Secondary College student, who woke up at 4am to cater for travel time, completed the sprint course in one hour and three minutes, beating home Warrnambool pair Travis Greening and Jason Dart.

Dowie, who won her group at the Australian age triathlon championships in St Kilda earlier this month, won from youngster Aurora Jarvis and Louise Ryan.

Johnson has joined a Geelong-based team called Beckworth Racing and is immersing himself in the sport.

The teenager, who hopes to study at Deakin University in Geelong in 12 months' time, will contest a 2XU triathlon in Sandringham next week followed by two more races in quick succession.

"This 2021-22 season I have been getting right into it," he said.

"I did race motorbikes and with COVID all the racing was gone so I turned away from it and starting training."

Johnson, who wants "to get stronger on the bike", said the physical and mental challenges of triathlons inspired him to improve.

"I just try to go hard and find limits," he said.

For Dowie, the race was a chance to see how she'd recovered following an arduous competition schedule.

"I am really pleased with myself as I did three races in one week, which was last week and one was the Australian championships so that was hard, and to try and back up again today...," she said.

"This is a really hard course. I just didn't think I'd have it in me so I am actually proud of myself for backing up.

"At 62, I am finally going to say it: 'I am proud of myself'.

"I never used to say it but I just don't know if I could do it again.

"That is the challenge, to see how long I can keep going for."

Dowie, who has competed at world duathlon championships, said the swim was again "the most challenging for me".

"That is my weakest leg. I never learned to swim until my 20s," she said.

"As I have gotten older my bike leg has improved but on this course it is a very technical, hard bike leg.

"It's very challenging. You've got the hills, a lot of twists and turns, a lot of speed humps and a lot of rough surfaces so you can't get a smooth run."

Dowie's schedule will now ease up.

"I am just going to support the local races and do Killarney, which is about a month," she said.

"I am just supporting the (Warrnambool Tri) Club and enjoying the competing and trying to hang in there for as long as I can."

The foreshore triathlon also included a shortcourse section consisting a 50m swim, 5km ride and 1.6km run as well as all-abilities and junior events.

Teams could also entry alongside individual entries.

The club's next major competition is the Killarney super tri on Sunday, March 6.

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