When Billy Kemper entered last month’s Peahi Big Wave Challenge, he had a lot going for him: confidence, having won the inaugural contest at the site known as Jaws a year earlier, and knowledge, having surfed the treacherous site since the Maui native was a teen.

He also had months of rigorous training, developed and supervised by his coach, Kahea Hart, himself a big-wave surfer and a certified sports trainer. A few days before this year’s contest, with a swell beckoning, Kemper was eager to see what he could do.

“I’ve been training my (butt) off for a few months here now, and I’m very curious to see how my body’s going to perform in waves that size and consequence,” he said at a workout session. “I’ve just been surfing here (on Oahu), and I feel the best I’ve ever felt, but it’s a total different feeling at Jaws. You’re basically trying to catch the biggest wave ever ridden.”

Kemper, 26, worked out in a garage maintained by Hart near Sunset Beach on Oahu’s North Shore. It’s equipped with a variety of exercise apparatus, including a stationary bike, a multiposition exercise machine, and inflatable exercise balls and straps for stretching. Flat TV screens on the walls flash a countdown so the workout moves at a steady pace.

There were no free weights, but at that point in the surf season, they were not needed. Kemper did his weight training and running earlier this year when North Shore waves were small, and now he was mostly interested in maintaining flexible strength, fine-tuning his sense of balance and honing a competitor’s edge.

“It’s not like a fight like a boxer, where it’s, ‘OK, I got three months to train for one event,’” he said. “I can have five swells back to back. We’re going to surf Jaws tomorrow. Then we might get a flight tomorrow night to surf Mavericks (in California) on Wednesday, then back here to surf the Triple Crown this next weekend. You’ve got to have your body ready to go like it’s a marathon, on call.”

FINDING BALANCE

On this day Kemper began his workout with a hard foam roller, working various parts of his legs across it to knead and loosen his muscles. “It gets the tissue membrane moving around rather than being stiff,” said Hart, 44.

Kemper then progressed to a 10-pound weight ball, moving it in big circles, swinging it from side to side, lunging forward while balancing it in one hand, stretching and working his core. If the movements were dancelike, the effort needed was not.

In a few minutes Kemper was grunting with each twist and turn.

Moving to an inflatable exercise ball, Kemper struck several yogalike positions, such as “downward dog” and, even more difficult, a three-legged downward dog, his arms holding up his body, one leg on the ball and the free leg rotating back and forth and twisting around his body.

Over the next few minutes, Kemper worked with training partner Ryan Hipwood, a professional surfer from Australia, on Indo Boards, a two-piece balance trainer that first appeared in the 1970s. The deck, which resembles a skateboard, can be placed on top of a cylindrical roller to develop lateral balance, or on an inflatable rubber cushion that allows the board to tilt in all directions.

With both Kemper and Hipwood standing on Indo Boards, they bounced a weight ball back and forth, working on hand-eye coordination while maintaining their balance.

Then, in an impressive test of balance and explosiveness, Kemper and Hipwood practiced jumping from the floor onto an upside-down inflatable cushion, then up onto a 36-inch-high wooden box, then down to an Indo Board resting on another inflatable cushion.

At Hart’s suggestion they landed in the classic surfer’s position, crouched low, one arm pointing down the line of an imaginary wave, the other flexed to maintain balance.

Kemper also practiced a powerful pop-up maneuver, leaping from a crouch onto the box, landing squarely each time without having to flail his arms for balance.

“What we’re doing now is just keeping things mobile, and all the movements are kind of positions or muscles that you would use when you’re surfing,” said Hart.

TRAINING PAYS OFF

Hipwood, 31, who competes in just a few events a year, said surfing has become so competitive that top conditioning is a necessity.

“Gone are the days of people thinking that they’re too cool to train,” he said. “You have to do it, like it or not.”

In about an hour, Kemper and Hipwood were preparing to leave for Maui after finishing off a “real fast version” of the workout, which normally runs about 90 minutes. “I just want to go to Maui feeling good,” Kemper said.

All that work paid off a few days later when Kemper dropped in on a monster swell, carving a sweeping, graceful arc as he flew down the approximately 50-foot face. Dragging his hand to slow down and bending his knees deeply to set his rail, he powered through a bottom turn, climbed the face of the cresting wave and into a yawning barrel of rushing water, then flattened his line and exploded through the foam into the clear.

Another hand drag and some nifty balance work on a bump helped him stay upright as he finished off the ride.

It was the first perfect “10” in the history of the Peahi Big Wave Challenge, and Kemper went on to win his second straight Jaws title.