Some thrill-seekers are taking the phrase "Go fly a kite!" to new heights.

That's right, kiting is making a comeback — with a twist. A growing number of daredevils are adding the childhood wind toys to their favorite outdoor activities, speeding them up and creating new sports, such as kite skating, skiing, snowboarding and even kite surfing.

Known as kite traction sports, the activities have seen a gradual increase in participants over the past decade — but have bloomed in the last couple of years, particularly kite surfing, according to kite traction enthusiast Bob Childs.

"The appeal … for some is the all-out speed and power," said Childs, 42, who sells kite sports equipment on doomwheels.com. "For some it is the sense of motion using only the force of the wind. I personally like both."

Kite traction enthusiasts, who are mostly between 25 and 30 but can be as young as 15, hold competitions around the world. The sports are most popular in Hawaii, the southern East Coast and entire West Coast of the U.S., Australia, Europe and South America, according to Childs.

All the kite sports involve holding onto — or being attached to — the strings of a power kite (a large kite that provides a lot of lift and pull), which can double the speed. Kite skaters, for instance, can hit 60 miles per hour with the power of a strong wind. And kite surfers can reach new heights with Mother Nature's help.

"On the bay, I watch these guys get, like, 30 feet of air," said Beth Mertz, a San Francisco, Calif., resident who snowboards and wakeboards. "Windsurfers get a couple feet, but with the kite they will fly through the air."

Other kite-inspired sports include kite buggying, which is racing around in a small go-kart-like vehicle with a power kite attached, and the particularly treacherous kite jumping, in which people can go 30 feet high over distances of a few hundred feet and perform flips and twists.

"This is surely the most dangerous of all kite traction sports and often leaves enthusiasts with broken bones," said Childs. "Kite jumping should only be performed on soft sand."

Kite traction activities, like other extreme sports, concern doctors because the injuries can be much more severe than those from mainstream athletics like football.

"When you talk about skiing or windsurfing, where you're using some kind of vehicle, the type of injuries are high-impact, high-speed injuries," said Dr. Sherwin Ho, an orthopedic sports medicine surgeon at the University of Chicago. "They can be more serious."

Ho, who is from Hawaii, said that because the speeds in "wind-aided or gravity-aided sports" are so much higher, orthopedic doctors see more fractured bones, complete dislocations (where multiple ligaments are torn) and severe head and neck injuries than with other sports.

"The injuries you're going to see are not much different from high-speed collisions," he said. "We recommend against those types of sports where there is risk of serious bodily harm or death."

Of course the danger is part of the thrill for many sportsmen.

"There is a risk," Childs acknowledged. "But for some, that is the kick."

Mertz, 31, who knows many kite surfers and kite skiers in California and Colorado, would give the sport a go, despite the potential for injury.

"I would totally try it if someone said, 'Here's the equipment, I'll show you how.'" she said. "I'd probably fall down and die, but whatever."

Childs had a scare while kite buggying and was suddenly yanked out of the vehicle and dumped on the ground by a gust of wind. He wasn't hurt, but the runaway buggy slammed into a parked truck and did $1,500 in damage.

He admitted that safety for the sport needs improvement.

In fact, kite traction can be so dangerous that some beaches in Hawaii, Washington state and Oregon have been closed to kite surfers; many lakes in Switzerland also forbid kite surfing, said Childs.

And doctors don't believe the benefits of kite traction sports are worth the risks.

"I think you can get adrenaline rushes in other ways," said Ho.