To the untrained eye, surfer Dusty Payne flies without effort or fear of falling. Speeding along the face of a wave, he’ll twist his body with a snap and launch himself 5, maybe 6 feet into the air. Then he’ll soar a distance of 10 feet before coming down.

Sometimes, Payne will spin himself 360 degrees through open space before landing on a churning mound of whitewater — the surfing equivalent of a bucking bull.

Payne makes it all look soft and feathery but the reality is that "airs," as they’re known among surfers, are a jarring maneuver that can tear knee ligaments and sprain ankles.

And Payne, a 25-year-old professional surfer from Lahaina, knows that as well as anyone. In the past three years he’s twice injured the MCL (medial collateral ligament) in his right knee, most recently in June when he also tore the meniscus, the tissue that cushions the knee joint. He previously injured an ankle so badly that he couldn’t surf for six months.

Throughout, Payne persevered by staying fit.

Rehabilitation and strength exercises have become a daily routine for Payne, who turned muscle into body armor.

When he won the Reef Hawaiian Pro surf contest Nov. 15 at Haleiwa, TV commentators couldn’t stop talking about how powerful Payne had become. When he finished second in the Vans World Cup of Surfing, held in thick, 15-foot waves at Sunset Beach on Dec. 5, one commentator remarked: "I think we are witnessing the rebirth of Dusty Payne."

Even as Payne’s run came to an end weeks later, in Round 3 of the Billabong Pipe Masters, his fitness was still a hot topic.

"I think these days if you want to be at the top, fitness is really important," said Payne, a man with a wide grin and a scruffy red beard. "I think the guys at the top take it as seriously as I do."

Payne took his fitness to a new level when he embraced CrossFit training about two years ago. Now he undertakes its mix of weightlifting and endurance drills five days a week. His coach, Brian MacKenzie of Southern California, who developed the CrossFit Endurance program, even showed Payne a more efficient way to paddle into a wave and to stand up — simple movements most surfers take for granted.

"These are things you kind of learn naturally and you don’t realize that certain movements may be taxing on a part of the body," Payne said. "So when you break it all down and look at what is hindering you and try to correct it, it is incredible the improvements you can make. For me, it is what I am constantly trying to do in trying to stay healthy."

BEING HEALTHY — and training with purpose — marked the first half of this year. Although Payne had surfed on the Association of Surfing Professionals’ World Championship Tour, injuries in 2013 forced him out this year. To regain his spot in the lineup next year, he had to do well in qualifying contests held throughout 2014.

By June, Payne was in South Africa and feeling fit when he paddled out for a practice session at a break off Ballito. In the water, he did what he always did.

"I did an air and landed on the board and the board snapped under my feet," Payne said. "My back leg stayed on the back part of the board and bent down violently inward. Instantly, I knew something was wrong."

He flew to Southern California the next day, hobbled by what he knew instinctively was an MCL injury to his right knee. The MCL keeps the knee from bending inward.

Surgery and rehab filled his calendar. Payne was convinced he could compete in the Vans U.S. Open of Surfing, scheduled to start less than four weeks later in Huntington Beach, Calif.

The injury was an emotional blow, however.

"He was devastated," said Dave Riddle, Hawaii regional manager for the Volcom clothing brand, one of Payne’s sponsors. "He had been injured before and that set him back. This was yet another one. He had been back and healthy."

Payne had to find the willpower to go through rehab one more time.

"He did and it was remarkable," Riddle said. "He put the work in."

Payne’s recovery included traditional exercises to increase strength and give him full range of motion, but he also used a machine that stimulates the muscles with electricity as he worked out. He had therapy sessions two to three times a day.

But he was in the water at Huntington Beach, Calif., for the U.S. Open.

Riddle, who serves as Payne’s coach, stood on the beach and tried to hide his concern. He knew that at Huntington one of the best ways to win a heat is to launch a big air.

"I was holding my breath and trying not to let him know I was more worried than I appeared," Riddle said.

Riddle had good reason. Although airs have revolutionized surfing, the constant impact of landing, even on perfect waves, is taking its toll. The water can feel as hard as a sidewalk.

Over the past five years, surfers’ ankles, knees and backs have been battered in increasing numbers, he said.

"This is normal in this industry," Riddle said. "It happens all the time."

At the U.S. Open, Payne did not advance out of the first heat.

Back in the CrossFit gym with MacKenzie, Payne continued his rehab.

For two months, MacKenzie worked Payne hard. MacKenzie made the surfer do single-leg squats and single-leg dead lifts with heavy weights. He gave him exercises to improve his balance and the way his legs dealt with the impact from landing an air.

AT HALEIWA, Payne flew above the waves like someone who had never been injured, MacKenzie said.

"He was wearing a knee brace all last year and he wasn’t wearing a knee brace at Haleiwa," he said. "And everyone was saying he doesn’t look like he was ever injured."

What happens next is up to Payne and how hard he employs exercises that reinforce proper movement and strength, MacKenzie said.

"Your body is designed to last a lifetime no matter what you do," he said. "If you want to surf the rest of your life, you should be able to, and that includes being on the pro tour for 20 years."

That sounds good to Payne, who, quite frankly, is just happy to be surfing again. He doesn’t take it for granted, and the same can be said for fitness.

"Competing is really taxing on the body," he said. "If I can constantly improve my body movement and be aware of what’s right and what’s wrong, I think I will have a much healthier career than I have had so far."