Aerobic workouts often leave you panting and out of breath, but you may also notice an increase in mucus production. While the causes of this congestion may be mild, you should take note of your symptoms and specific triggers to determine the root cause. Your workout may be causing excess mucus even up to a day after you've finished exercising, so don't be too surprised if your aerobic workout is causing extended effects and symptoms.
For many people, aerobic activity triggers a slight respiratory irritation. When you exercise at a moderate pace, your body requires more oxygen, increasing the rate of respiration. In contrast, your resting body breathes more slowly which allows the air entering your nasal passage to be moistened and warmed before entering the lungs. However, during exercise, you breathe more through your mouth than your nose, which causes dry and cool air to go directly to your lungs which not only irritates your mouth, but can also dry out mouth tissue, causing an overcompensation of mucus production after a workout. Staying hydrated before, during and after an aerobic workout may decrease your symptoms.
When you exercise outdoors, you expose yourself to environmental allergens and irritants. In many people who have an allergy to pollen or are sensitive to exercising in hot or cold weather, these factors cause an overproduction of mucus, which may last for hours after your workout has ended. Even when exercising indoors, you may still be exposing yourself to irritants such as airborne bacteria, strong perfumes and harsh cleaning agents. All of these factors have the potential to cause mucus buildup, especially if you are sensitive or have moderate to severe allergies.
Immune System Depression
While exercise improves overall health and is associated with a reduced incidence of infection, prolonged bouts of exercise cause a depression in immune system function. If your aerobic workout lasts more than 90 minutes, then you may be decreasing the function of your body's natural protection measures. In a 2007 review published in the "Journal of Applied Physiology," researchers studied athletes who experienced post-exercise respiratory irritation and inflammation. While these athletes were not sick, their extended periods of exercise caused a decrease in immune cells and an increase in inflammatory cells, leading to post-exercise irritation and increased mucus and phlegm production. Your post-exercise mucus buildup may be caused by these factors, especially if you work out for longer than 90-minute sessions.
Illness and Disease
Because acute bouts of exercise depress the immune system for anywhere from three to 24 hours after exercise, your mucus production may be caused by an upper respiratory tract illness. While this condition may not be serious, respiratory tract illnesses cause mucus production and other symptoms commonly associated with colds and fevers. While your symptoms may be mild, be aware that you should take them seriously since they could be indicators of a more serious condition. Bronchitis, swelling and inflammation of the air passages to the lungs, causes increased mucus production and may be exacerbated by aerobic exercise. If you notice your mucus is a yellow or green color, you likely have some sort of infection or illness. Even without this symptom, you may want to ask your healthcare provider about excess mucus production to rule out any potentially serious health problems.