In two years, professional triathlete Danielle Mack saw 18 different physicians: family doctors, gastroenterologists, neurologists, allergists, pulmonologists and specialists of other sorts. She had many tests, but she got no explanations for what she called her "invisible illness."

Mack's symptoms included numbness in her legs, lightheadedness, dizziness, shortness of breath, chest pain, nausea and full-body cramps. The signs suggested exercise-induced asthma. Her physicians treated her with an inhaler, which not only did not work but also made her feel worse. Finally, Mack, who lives in Boulder, Colorado, tried a stress test at National Jewish Health Hospital in Denver.

Under the supervision of pediatric pulmonologist Tod Olin, Mack rode a stationary bike while a tiny camera, inserted through her nose, filmed her vocal cords. As she increased her pace, the cords narrowed, blocking air. The result: a repeat of the symptoms she had been experiencing while training and racing. Olin diagnosed her in September with exercise-induced laryngeal obstruction, or EILO.

Exercise-induced respiratory symptoms are fairly common in adolescents and young adults (Mack is 30 years old), and the most likely explanation is asthma. A condition that has been recognized since the early 1980s, EILO is often missed by physicians, Olin said.

"Without intending to, patients often mislead doctors by unconsciously using the word 'wheezing,' which causes confusion," Olin said. "If patients were to act out symptoms, the physicians could make a more accurate diagnosis, but that's generally not part of the routine screening."

This confusion leads physicians to prescribe asthma medicine, as in Mack's case. "The next step is often to throw more medicine at the problem," Olin explained, "which doesn't fix anything."

The prevalence of EILO is surprisingly high, Olin said, at around 5 percent of adolescents and young adults.

"Compare that to Type 1 diabetes, for instance, which is around 1 percent," he said, "or asthma, which stands at 8 to 12 percent."

Perhaps even more problematic is the lack of knowledge about treatment.

"The clinical reality is that even if you have the right diagnosis, the breathing exercises that have served as the standard really don't work for most patients," Olin said. "By the time patients get to me, they've inevitably tried multiple approaches and are discouraged and frustrated."

Erika Westoff, a mental-skills coach in Pleasanton, California, knows well the toll that the condition can take on patients. Affected athletes often feel helpless, hopeless and extremely frustrated.

Westoff became aware of EILO when she met a high school soccer player. "She had just been diagnosed with EILO but couldn't find a fix," Westoff explained. "I wasn't familiar with the condition, so I told her we'd start the journey together."

Meanwhile, Westoff began helping that soccer player by employing the approach she offers to other athletes dealing with stress. She teaches mental skills such as setting and tracking goals, learning imagery skills, improving focus and managing emotions. She said her techniques worked well enough that the soccer player didn't have to seek further treatment. But that's not always the case.

Shortly after, Westoff learned of Olin's breathing technique for treating EILO. The two now often refer patients to one another.

"I think most patients need both the mental and physical treatment to get on top of EILO," Westoff said. "Dr. Olin's technique is key for those times when a patient has an episode and needs rescue breathing to get on top of it."

Olin stumbled onto his treatment while filming the vocal cords of a patient. "We were using the camera, and the athlete began crying because it's a scary feeling to have your throat close up as it does with EILO," he explained.

As she was crying, there was a combination of sniffling through her nose and gasping for air, Olin said, that led the patient to open her vocal cords for a moment. "The technique involves a very controlled change in speed and resistance of the airflow in an unnatural way," he said.

In an October article in the Journal of Voice, Olin and colleagues reported that, of 61 patients they evaluated over about 18 months, 79 percent were able to employ the technique in a high-intensity exercise situation, and 66 percent were able to breathe normally.

An out-of-state athlete seeking treatment typically pays about $6,000 and spends about a week at Olin's clinic learning the technique. This is the approach Mack took. "Some patients can feel the difference right away," she said, "but it took me a while to get it. I can say it's made a massive difference for me."

Mack is grateful to have found a solution, though she is still struggling. At the Ironman Malaysia triathlon on Nov. 11, she had a flare-up midrace and could not finish. She plans to return to Olin for a follow-up.

Westoff said that when patients work hard on both the breathing techniques and the mental training to control the stress of the situation, success rates can be high. "An athlete's belief in the problem and a commitment to treat it is a big part of the solution," she says. "The condition is predispositioned for these athletes, but it's very treatable with the right resources and hard work."

Awareness of the condition and its treatment is slowly spreading, Westoff said. "I'm starting to hear from colleagues who are seeing EILO show up in their offices, too," she said. "Where diagnoses often took up to two years, I'm hearing of patients who are now closer to a year or even six months."