The three-day event pits athletes against a gruelling program of workouts set to pumping music at WIN Entertainment Centre.

Athletes are timed while they pull off various feats - rowing, lifting, pull-ups and the excruciating "burpee muscle-ups" - with the top three men, women and teams then granted a pass to the World CrossFit Games in Carson City, Los Angeles.

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The CrossFit movement began in the United States in 2000 and has since spawned more than 6000 "boxes", or gyms, worldwide, including more than 370 in Australia.

Cronulla competitor Nathan Beves said the sport attracted especially competitive people, but the community was ultimately supportive.

"There is a bit of arrogance, but that happens in every sport," he said.

"It's a really good community. Seventy per cent of the people are obliging and say hello.

"In your box everyone supports each other. Everyone's improving to some degree and everyone enjoys seeing it happen."

Teams of three men and three women opened the first of three days' competition yesterday, before individual women's and men's heats began.

Workouts included 30 of the "burpee muscle-ups", where competitors drop to the ground, jump to a set of rings, then pull their entire body weight up and atop the apparatus.

The first round of men's competition included a 1000-metre row, 50 "45-pound thrusters" - involving a weight bar - and 30 pull-ups.

Australian regional director Mick Shaw said regional competitors had been selected from across Australia and New Zealand.

Mr Shaw says the sport has taken off in the past five years.

"I believe a lot of people have been drawn to CrossFit because it's real movement, it's natural to our DNA," he said.