It might sound extreme, but climbing 120-foot trees in five minutes is old hat for Gainesville resident Odis Sisk.

Sisk, a six-time Georgia Tree Climbing Champion, will be competing in his third international tree climbing competition July 23-27 in Sydney, Australia.

"You're climbing without any assistance from anything that could damage the tree," Sisk said.

That means ropes, harnesses and safety equipment, and no shoes with spikes.

Sisk is a certified arborist who owns Global Tree Preservation in Gainesville.

He is a third-generation tree worker, and most of his job is spent high above ground, preserving and maintaining trees.

He started competing in the Georgia competition in 2006 and followed with Southern Chapter competitions. Only one person from each chapter can compete in the international championship.

Sisk said he will be one of 35 men and 25 women in the 2011 competition.

"Every competitor climbs the exact same tree and everyone has the same time limit. You're graded on efficiency, safety and creativity," Sisk said.

Creativity scores are based on finding efficient routes up the tree and innovative ways to maneuver, such as jumping.

Workstations are situated around the tree. During the five minutes competitors have to climb, they ring bells at each station to simulate different tasks they perform in their jobs, including sawing limbs.

"You really have to move quickly. If you miss one station in a tree, you won't make it to the finals," Sisk said. "The competition level is so high."

Fewer than 10 competitors make it into the final round. The final tree is kept hidden from view, and unlike the work climb competition, climbers must survey the tree for safety hazards and set up their own ropes. There are 25 minutes to complete the final tree climb.

The work climb is one of five events at the international championship. Scores from the events are tallied to determine the winners.

In the limb-walking event, competitors must walk from the trunk to the end of a branch without causing a bobber attached to the branch to drop.

Other events include a limb toss, jumping out of a tree and an aerial rescue event.

Sisk trains year-round for the competitions. His intense practices begin one to two months before an event.

"You have to maintain a decent diet and workout," he said. "You climb as fast as you can for work. I try to climb as many trees as I can while working."

The height of the work climb depends on the location of the competition.

Competitors can win prize money, but what Sisk said was even more valuable was winning free work gear and sponsorships to attend future championships.

"It should be fun. It's been exciting," he said.

The Australia competition will be his last for a while. In 2012, Sisk will chair the Georgia Tree Climbing Championships, set for February in Gainesville.