Water fitness: Extreme wave rider, SUP champ Kai Lenny shares his workout routine

From big-wave surfing to stand-up paddle surfing, racing and more, Maui's Kai Lenny uses on- and off-water training to prepare his body for the waves.

Some athletes dabble in more than one sport. Maui’s Kai Lenny excels in them, competing internationally in everything from big-wave surfing to stand-up paddle surfing and racing, from kite surfing to tow-in surfing and more. With so many water sports in Lenny’s life, the waves serve as a gym.

“I use these other sports as forms of working out,” Lenny says. “It keeps training creative and exciting. It doesn’t get stale. As soon as it gets stale, you lose that motivation.”

While to a certain extent all of what Lenny does—and he currently competes in eight sports—involves riding waves, making the sports similar enough they can feed off one another and allowing him to take something he’s learned from one sport and move it into another. But the differences allow him to cross-train and use different muscles through all the sports.

Take wind surfing. Lenny says that sport builds his strength and core muscles for stand-up paddle boarding because the constant force in the sail forces him to pull and hold onto the rig while jumping.

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With so much going on, Lenny says the hardest part is saying no. He could compete every weekend of the year multiple times over. “I choose the ones I like to do and choose the biggest races and biggest events,” he says. For now, his competitive focus is on stand-up racing and big-wave surfing’s world tour. “I try not to oversaturate to perform the best in the events that I do.”

While the on-water training takes focus, he says the training for stand-up racing requires a more stringent plan, using endurance paddling and sprint intervals along with more mellow days of paddling technique training to keep him sharp. But that doesn't mean Lenny isn’t flexible when he gets a call that he needs to be in Mexico in 72 hours for a big-wave competition. “To go from paddling in controlled flat water to death-defying waves that are unpredictable, that takes a lot of feeling and concentration,” he says. “It is just a different approach and you have to stay very adaptable.”

Lenny does hit the gym for an hour three times a week for high intensity work or recovery, but he feels like training using the sport is the best way to build strength specific for that discipline. His routine, though, depends on how he wakes up. And where his heart rate stands.

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Every day he wakes up and checks his heart rate, using the number to determine how hard he’ll push himself that day. When Lenny takes to the water, he doesn’t stop monitoring his heart rate. Or applying it to his training. “If I feel I am pushing hard and my heart rate says otherwise, I push harder,” he says. “Your heart isn't going to lie. If I’m working too hard, I switch up equipment or technique. It is super important to know how you are feeling. I’ve gotten so used to knowing what my heart rate feels like that I don't even need to look at a heart-rate monitor.”

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Lenny has taken his heart rate every single day for over a year, tracking the patterns that help him understand how he needs to train in specific days and seasons. “A lot of it is mental,” he says. “You heart rate is good and it dictates how your body actually feels versus how your mind feels.”

With so many water sports in Lenny’s repertoire, he gets excited about the opportunity to mesh them together in competition, such as with the Red Bull Heavy Water race off Ocean Beach, Calif., in late summer. Part of the Stand Up World Series circuit, Lenny will be one of 40 SUP athletes padding an open course that stretches 7.5 miles, including under the Golden Gate Bridge, and includes waves over 10 feet high, Lenny says it gets him more excited than a normal race because he can take on the giant waves with the paddling.

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“What interests me is going to the pinnacle of the extreme side of stand up paddle racing,” he says. “It is a really exciting event because of waves of consequence. There is a lot bigger surf. It is quite entertaining. It is the most fun and exciting race I could do just considering the conditions involved.

“I want to be able to all sports at the highest possible level, getting me scared, being extreme and pushing me mentally and physically.”

Eight different water sports give Lenny ample opportunity for that extreme.

Tim Newcomb covers sports aesthetics—stadiums to sneakers—and training for Sports Illustrated. Follow him on Twitter at @tdnewcomb.