Viral or bacterial infection
Acute bronchitis is a result of viral or bacterial infection causing your bronchial tubes, which carry air to your lungs, to get inflamed and swollen. This causes excess mucus production which irritates the lungs and generates a nagging cough. Dr. Alan Greene, pediatrician and Clinical Professor of Pediatrics at Stanford University, notes that cold air in and of itself does not cause colds or bronchitis according to research. However, running in the cold can make you more likely to get ill once you have been exposed.
The immune system can be depressed by strenuous exercise such as running. Antibody and T-cell production can be depressed by acute intense exercise according to a position statement published in the 2011 “Exercise Immunology Review” by the International Society of Exercise and Immunology. T-cells and white blood cells are infection fighting mechanisms of the body. The white blood cell count increase immediately after strenuous exercise, followed by a drop to low levels before returning to normal. During a period of low white blood cell levels, immunity to infection is decreased.
Disturbances in your immunity caused by exercising.
Research results reported in the December 2003 issue of “Aviation, Space and Environmental Medicine” concluded that exercise done in conditions of extreme cold or heat, produced disturbances in immunity. The cold temperature for this research was 8 degrees celsius with 50 percent relative humidity, and the high temperature was 38 degrees celsius with 45 percent relative humidity. The disturbances in your immunity caused by exercising in environmental extremes such as heat, cold or at high altitude is the result of your body’s stress response, and promote the development of respiratory infections such as bronchitis.
Your respiratory system has a thin covering of mucus called the mucous blanket, which traps viruses and bacteria. Cold air can affect the mucus transport system according to Dr. Greene. Exercising in cold air increases mucus production but also makes it thicker, making it more difficult to clear the mucus. As a result, bacteria and viruses contained in the mucus stays in contact with your lungs longer, increasing the risk of infection.
Running in cold air.
According to Dr. Greene, breathing cold air through the nose can also increase nasal congestion and stuffiness. This makes it more difficult for the body to remove inhaled bacteria and viruses. A release of the chemical called histamine can also be caused by the inhalation of cold air, which can cause wheezing or exercise-induced asthma. All these factors combined increases the risk of acute bronchitis when you run in cold air and are exposed to a bug. It is recommended by Dr. Greene that you drink plenty of fluids to keep your mucus thin, and breath through your nose while running in the cold.