I've been obsessed with this for eight years," says Shawnee Rivera about Muay Thai kickboxing.

This petite 5-foot-5-inch English teacher at Cupertino's Homestead High—with dancing brown eyes, red-streaked French braids and a tattoo of Georgia O'Keeffe's Calico Flower on her foot—practices one of the world's most deadly martial arts. Fighters kick so hard that the sound of their bare feet hitting their opponents' gloves and chest-covers sounds like gunfire.

 Muay (pronounced "Muy") Thai is Thailand's national sport and evolved from battlefield fighting in ancient Siam. The National Geographic Channel's "Fight Science" hit on the reason for its appeal as a competitive sport: it allows all types of strikes in the ring, and is especially known for devastating knee, elbow and shin strikes.

In just six years, the 34-year-old Rivera has risen to contend for the Olympics of Muay Thai—the annual World Championship, which is organized by the International Federation of Muaythai Amateur (IFMA). Rivera hopes to make the U.S. team this year and compete in the 2008 World Championship.

Her ascent has been made all the more unlikely by two health scares that threatened to knock her out of contention permanently. But the setbacks seemed only to increase her dedication and devotion to Muay Thai. Rivera is also a mountain biker and snowboarder who has run triathlons and marathons. She says not only did kickboxing put her in the best physical shape of her life, it's also made her mentally stronger and a more balanced person.

"It's a thinking person's sport," she says. "You just can't go out there and throw a bunch of punches and kicks and expect it to do you any good. It's something for your entire self. There's discipline, there's respect, there's so many wonderful lessons to learn."

That's what inspires her intense devotion to Muay Thai, she says.

"I think you come in here and blow your own mind at the things you're able to do, and how powerful and safe you start to feel because of the self-defense aspect of the sport," she says. "All my life, I've struggled with low self-esteem. Right away, I felt autonomy and internal strength."

Her coach, Derek Yuen, says the power of Muay Thai comes from its uncompromising style.

"It's considered the most deadly of the striking arts," says Yuen. "There's a simplicity to Muay Thai. It's based upon effective techniques. There's nothing fancy, there is no strike in Muay Thai that doesn't have a high probability of success. If you want to know how to damage someone the most effectively, it's Muay Thai. I'm a mechanical engineer. I'm analytical. Muay Thai's style is very direct and simple—not as in easy. It's simple as in there's no fluff."

Rivera was already training intensely at the American Kickboxing Academy on Hillsdale Avenue in San Jose when she had her first big setback—a car accident that kept her out of the sport for a year. But when she recovered, she worked so hard that her Yuen asked her if she wanted to fight competitively.

"I said 'No, that just seems so violent and brutal,'" remembers Rivera. "And then I went and watched his fight, and my good friend Josh Thompson's fight. That night I told my coach, 'I want to fight,' because everybody from this gym completely dominated their opponents."

She was inspired by what she calls the "amazing technical savvy" of her coach.

"I thought that if I could have one-eighth of what he has, with the amount of cardio that I have, I think I could be really good at this. I dedicated my life from that point forward to kickboxing."

But then Rivera had to quit the sport for another two years. Her doctor advised it after her aunt and great-grandmother had stokes, and her mother was discovered to have two aneurisms. Rivera stayed in shape with running, biking and snowboarding, but a piece of her life was missing.

After seeing how much of an effect the absence of kickboxing was having in her life, it was her chiropractor who advised her to go to three doctors for second, third and fourth opinions, which she did. "I had MRIs and cat scans; they all said I was fine," she says. "The following day I went back to the gym."

Comeback Kid

With a soccer coach dad, Rivera was athletic growing up, including her years at Willow Glen High School. But while attending Sonoma State, she says, "I hardly ever ran. I gained a lot of weight and I was very unhappy."

When a friend suggested kickboxing to help her get back in shape, she thought it sounded too violent. 

"Then I went to Herb Cody's gym in Petaluma," she says. "Within five minutes, I was completely, 100 percent addicted."

After graduation, Rivera moved back to San Jose, eventually going back to school for her teaching credential. She started out at Gilroy High School six years ago before coming to Homestead High—which famously graduated both Steve Jobs and Steve Wozniak—where she teaches contemporary literature and writing classes.

When she found the American Kickboxing Academy on Hillsdale Avenue, she started going to their classes every day. Today Rivera trains at AKA five nights a week. Located in a dreary suburban strip mall between a box store and a billiards-and-bar-stool supply, AKA has produced a dozen world champions, and people come from all over the United States to train with AKA's founder Javier Mendez, a two-time world champion, along with other national and world title holders.

The World Championship is held at a different time and place each year. Rivera says this year's is likely to be held in the fall in Seoul, Korea.

There are no tryouts to get on the U.S. team. Contenders apply to Fairtex Muay Thai Fitness, in Mountain View and San Francisco; they're the gym that organizes the U.S. team for the championship. Yuen says a fighter's application includes his or her stats and a videotape of fights, and organizers choose whoever they think has the strongest chance of doing well.

In April, Rivera won her first fight. She hopes to be matched at the next fight, which may be as soon as June 21, at the San Jose Event Center. After that there's nothing set. Yuen says she has a decent chance at the U.S. team if she can keep up her training regime, win a few more fights and raise the money to go. He said there isn't a set number of fights that she needs, but if she only has one win when she applies, she likely won't make the team if others in her weight class have more.

"Girls who apply will have between five and 10 fights, but if they can't raise the money and Shawnee can, she can make the team," he says. "She's seeking more fights to better her chance of making [it]."

In the end, Yuen says, because contestants are self supporting, "only the hungry apply."

And Rivera's hungry.

In Training

It's 7pm on a typical Monday, and the 6,300-square-foot gym at AKA is filled with 60 to 80 young, hard bodies. Most are taking a kickboxing class, others are training. Rivera is with coach Yuen and the fight team, up in the professional-size boxing ring. The high ceiling pulls all of the sounds into one soft mix: Bags being punched, yelps of encouragement, the echo of bare feet striking training pads and reggae music playing for the class.

 Rivera is barefoot in red ankle guards, with manicured burgundy toenails. She smiles as she repeatedly kicks Yuen's padded chest hard.

In other fighting styles, Rivera might stand out more as a woman, but women make up about 25 percent of the sport's U.S. practitioners. Rivera says another reason women don't stand out at this gym is because, like gymnastics, Muay Thai uses all muscle groups. Men don't bulk way up and women get firm, and fighters of both sexes end up looking quite similar in build.

Rivera has a challenge ahead of her in her bid for the U.S. team, but she feeds on kickboxing's intensity—win or lose.

"There's a huge sense of accomplishment when you win and a huge sense of accomplishment when you get your behind handed to you," she says. "Because you're like, 'Oh, I just learned so much about my own fight, my own style and my own ability to thrive.'"

Rivera also draws inspiration from her other passion, teaching.  

"All my students, every single one of my students motivate me," she says.

She gets so wrapped in her students that kickboxing actually seems like a wind-down. "When we talk about their lives and the hardships they're going through, some things I cannot change, but I can come here and work through it and not take that home with me," she says.

If she does make the World Champ-ionship, Rivera says, it won't be just herself but also all of the people around her that she'll be representing.

"I love all of the paradoxes that exist in this sport," she says, "the amount of love you have in your fight team, the amount of love you have for your coach and hate at the same time because he pushes you so hard. It is a huge team environment and even though you're in the ring alone, you're bringing all these people with you."

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