Asthma Subgroups: Winter Asthma

There is a unique subgroup of asthma that affects winter athletes. It’s sometimes called Cross Country Skiing-Induced Asthma. You might also refer to it as Winter Olympian Asthma, Cold-Air Induced Asthma, or simply Winter Asthma. Here’s what to know.

What do studies show?

In one study, researchers crunched data from Olympic games between 2002 and 2010. They found that 8% of Olympic athletes had asthma. This makes asthma the most common chronic disease among Olympians. They also found that winter Olympians were more likely to have asthma than summer Olympians.1

Researchers in the early 1990s looked at cross-country skiers. Their studies showed a higher incidence of asthma among cross-country skiers than the general population. It was suspected that asthma in skiers was due to high endurance exercise in cold temperatures.2

One study showed almost 50% of cross-country skiers had Exercise-Induced Asthma (EIA). Not far behind were ice skaters and hockey players. 2 Also affected are runners and cyclist who practice in the cold winter air.3

One study showed almost 50% of cross-country skiers had Exercise-Induced Asthma (EIA). Not far behind were ice skaters and hockey players.2

Cross country skiing was the first winter sport to be linked to asthma. Because of this, this asthma subgroup is sometimes referred to as Cross Country Skiing Induced Asthma. Today it’s known to affect other winter athletes as well. So, we will refer to it as Winter Asthma.2-3

Why might cold air cause asthma?

Researchers are still not sure. But, it may begin with the fact that cold air tends to hold less water than warm air. It’s the job of your nose to both warm and humidifies this inhaled air. When you’re vigorously exercising, your nose can’t keep up. This causes airway cells to give up some of their water to humidify inhaled air.3

When this happens, an abnormal immune response occurs. It begins by airway cells releasing mediators of inflammation, like histamine and leukotrienes. This causes airway inflammation.

This inflammation further irritates airway cells causing bronchospasm. This causes asthma or asthma-like symptoms.

Over time, this inflammation becomes chronic. This makes airways increasingly hypersensitive. So, over time, vigorous exercise more easily triggers asthma symptoms. 3

In this way, vigorous activity in cold air causes damage to airways. This occurs gradually over time. Every day for 2-3 hours an athlete might train for a sport. Gradually, over time, this damage progresses until symptoms become more aggressive. This is what usually leads to a diagnosis.

For this reason, Winter Asthma usually has a late onset. This means it’s diagnosed later in life, such as in adulthood.2-3

What are characteristics of Winter-Induced Asthma?

About 90% of asthmatics also have Exercise Induced Asthma (EIA). This is when asthma symptoms are caused by vigorous activity, such as running. But, unlike typical asthmatics, those with Winter Asthma tend to only have EIA.3-4

For example, Winter Asthmatics tend to not have allergic asthma. They do not have allergies. Their asthma is specifically caused by vigorous exercising in cold temperatures. For this reasons, it’s sometimes referred to as Exercise-Induced Bronchospasm (EIB).3, 5

Furthermore, allergic asthma involves white blood cells called eosinophils. The type of inflammation formed is eosinophilic inflammation. This type of inflammation responds nicely to corticosteroids. It can be controlled by traditional asthma controller medicines, like inhaled corticosteroids.5

Winter-Induced Asthma tends to involve other white blood cells, such as neutrophils. It also involves some degree of airway remodeling. Because of these factors, it usually doesn’t respond to corticosteroids.5

What does this mean?

Winter asthma is a relatively new subgroup of asthma. It’s usually diagnosed in those who have never had a previous diagnosis of asthma. Plus, it’s usually only diagnosed in those who participate in winter sports that involve vigorous physical activity. Examples include cross-country skiing, hockey, running, or cycling.

A doctor can help you get to a proper diagnosis. Once a diagnosis is made, your doctor can help you obtain good asthma control. This may entail taking asthma medicines. It may also involve working with a trainer to learn strategies for pacing yourself


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