Sprinting up a mountain in skis would be difficult for most people, but reaching a speed of 11.4 mph while doing so? Without video proof — a social media video that has garnered more than 15.5 million views — people may have doubted it even possible. But not for Norwegian cross-country skier Johannes Hoesflot Klaebo, who went viral for his impressive feat and made history at the Milano Cortina 2026 Games by earning the most career gold medals of any Winter Olympian.
Cross-country skiing is “one of the toughest sports in the world,” explains pulmonologist Fernando Holguin, MD, head of the Division of Pulmonary, Allergy, and Critical Care Medicine at the University of Colorado Anschutz Department of Medicine, particularly when it comes to the respiratory system. In fact, previous research found that more than half of elite cross-country skiers experienced asthma-related symptoms like wheezing, shortness of breath, coughing, and chest tightness, he explains. Some athletes even lost lung function as they got older. And it’s not just cross-country skiers who are at risk.
“Respiratory problems are really common in athletes,” says Tod Olin, MD, a respiratory consultant for the United States Olympic and Paralympic Committee and USA Swimming, an associate professor of pediatrics at the CU Anschutz School of Medicine, and a professor of medicine and pediatrics at National Jewish Health. “The most common is asthma, which affects a high proportion of elite-level athletes.”
An estimated one in five athletes have lower airway dysfunction — a condition that is also referred to as exercise-induced asthma or exercise-induced bronchospasm — according to research by a subgroup of the International Olympic Committee Consensus.
Though asthma is the most popular breathing issue, there are two others that may be affecting athletes, explains Olin. The first is exercise-induced laryngeal obstruction (EILO), also called vocal cord dysfunction, where the vocal cords close during high intensity training. The second is breathing pattern disorder, where athletes’ breathing patterns become disorganized and worsen during exercise. People from across the globe will travel to the National Jewish Health Exercise and Performance Breathing Center, which Olin is the director of, to seek care for these conditions — including some Olympians.
Holguin describes asthma as a “constellation of symptoms” rather than a singular disease, given that there are different types and manifestations of asthma. Type 2 asthma, for instance, is characterized by patients having elevated levels of eosinophils, a type of white blood cell that is activated during allergic reactions and parasitic interventions. Although some Olympians have this type of asthma, others have exercise-induced bronchospasm, where the airways constrict as a result of intense activity.
When an average adult is sitting, they typically breathe between 5-10 liters of air per minute, Holguin explains. After going for a jog, this rate may increase to 30 liters per minute. Research suggests tall, male, elite cross-country skiers, on the other hand, may increase their breathing intake to a little more than 200 liters per minute — roughly 20 times the normal resting rate.
Overall, asthma is considered to be the most common chronic medical condition among Olympians. However, research suggests that the prevalence of asthma may be higher in some sports than others, particularly among winter sports.
“There’s definitely an association between winter sports and asthma. When athletes train for many hours in cold temperatures and breathe at a fast rate, it can cause changes in the airways over time that can lead to exercise-induced bronchospasm,” Holguin says. “Research has suggested that more than half of elite-level skiers, about 20% of figure skaters, and roughly 15% of hockey players had evidence of asthma symptoms.”
Exercise-induced bronchospasm may be an “occupational hazard” of being an elite athlete, Olin says. However, this is not necessarily negative when it comes to athletic performance. Research has found that people with asthma tend to win more medals than those without asthma, he notes.
“It’s this really weird phenomenon, and it’s not believed to be related to the use of medication,” Olin says, noting that there are many theories as to why this may happen. “No one really knows why, but it is a consistent trend.”
Though much of Olin’s work — with Olympians and the general public — is focused on asthma, many people also seek his expertise on a condition called EILO, where the vocal cords close during intensive exercise.
“It’s a really performance-limiting condition,” Olin says.
He was involved in research conducted by a subgroup of the International Olympic Committee Consensus that found EILO is common in athletes and needs to be distinguished from other respiratory conditions — a pressing issue given that EILO is commonly misdiagnosed as asthma.
“We tend to see it in younger patients, from the ages of 15 to 25, but we’ve also diagnosed it in people who are 45 years old and likely have had it for 30 years,” he says.
Doctors are still unsure what causes EILO, and though there is no current evidence of the condition causing permanent damage to the vocal cords, it’s common for people with the condition to stop exercising completely out of frustration.
One of the main reasons why people from across the country and the globe travel to the National Jewish Health Exercise and Performance Breathing Center is because of its unique therapeutic approach. Health care providers like Olin will place a tiny camera through a patient’s nose so they can see the vocal cords. Then, while the doctor looks at the vocal cords, the patient will run on a treadmill as fast as they can.
“What we do to fix the problem is teach the patient how to essentially keep their vocal cords open while performing high intensity exercise,” Olin says. “It’s an elaborate process, but we bring patients in for three to four half-days so we can teach them different styles of breathing so they can cope with this condition.”
Teaching coping mechanisms is also how Olin approaches treating breathing pattern disorder, a condition that often affects younger people after they become sick with an illness like COVID or the flu and has affected Olympians before.
“With this condition, people feel out of breath and get disorganized when they breathe, which worsens when they exercise,” he says. “We teach them strategies to cope with this.”
Despite the prevalence of asthma and other breathing issues among elite athletes, both Holguin and Olin caution people from steering clear of exercise.
“Don’t let concerns about asthma discourage you from participating in winter sports,” Holguin says. “If you have asthma-related symptoms, seek professional advice and get tested to see what the actual problem is, because there are medications or interventions that can prevent or manage those symptoms effectively.”
Olin encourages patients with breathing issues to document their problems with their phone, explaining that videos, pictures, and audio can be helpful in diagnosing problems.
“If you have asthma, that’s not a reason to avoid exercise. If we can get athletes with asthma and EILO winning medals, we can help you achieve your exercise goals,” he says. “If you have a problem, that’s why we’re here.”