Exercise, especially in cold air, is a frequent asthma trigger. A form of asthma called exercise-induced asthma is triggered by physical activity. Symptoms of this kind of asthma may not appear until several minutes of sustained exercise. The kind of physical activities that can bring on asthma symptoms include not only exercise, but also laughing, crying, holding one's breath, and hyperventilating.
The symptoms of exercise-induced asthma usually go away within a few hours. With proper treatment, exercise-induced asthma does not need to limit your overall physical activity.