The prevalence of exercise-induced bronchoconstriction (EIB) is 10% in the general population, up to 90% of those with asthma, and 50% of those with allergic rhinitis.
From the NYTimes:
Most experts think that the problem is not with the coldness of the air but with the "dryness."
Exercise-induced asthma has been diagnosed in as many 50% of all elite cross-country skiers and almost as many world-class ice skaters and hockey players. It’s far more common in winter athletes than in those who compete in the summer, although 17% of Olympic-level distance runners have been given the same diagnosis.
Exercise-induced asthma is not quite the same condition as asthma. The “preferred term” for exercise-induced asthma is exercise-induced bronchoconstriction, or E.I.B. “It’s a reversible, obstructive airway disease” that typically begins about 5 minutes after you stop exercising — particularly if your exercise was intense, “at 85 -95% of maximum heart rate,” Dr. Randolph says.
Exercise-induced bronchospasm (EIB) (click to enlarge the image):
About 90% of people with asthma also suffer from E.I.B. But people can also suffer from E.I.B. without underlying asthma.
Lungs need water-saturated air. If the air entering your bronchial tubes is dry, as it usually is in winter, the cells lining your airway release their own moisture to humidify it.
“Think of a sponge being squeezed,” Dr. Randolph says. The squeezing and loss of moisture prompt certain cells within the bronchial tube to release allergic chemicals that initiate an inflammatory process, slowly closing your throat. Thankfully, the process is “self-limiting,” Dr. Randolph says. “No one dies” of exercise-induced bronchoconstriction. (Although some athletes have died from uncontrolled asthma attacks, a different issue.)
Those study subjects who perspired, spit and cried the least were also the most prone to exercise-induced asthma. However, drinking more water hasn’t been shown to combat E.I.B.
ATS practice guideline: exercise-induced bronchoconstriction:
Why Do So Many Winter Olympians Have Asthma? NYT, 2010.
Exercise-induced asthma and bronchospasm
49-year-old man with childhood asthma who was told he would never be able to do exercise runs a marathon every day for a year. CNN, 2011.
Asthma remains the most common health problem among elite athletes. "Regular, moderate exercise can improve your immune system, which can also help avoid asthma attacks". BMJ, 2012.
An official American Thoracic Society clinical practice guideline: exercise-induced bronchoconstriction. Am J Respir Crit Care Med. 2013 May 1;187(9):1016-27. doi: 10.1164/rccm.201303-0437ST.