Q I’ve heard that running can improve asthma, but I suffer from exercise-induced asthma, especially after pushing myself. Will it improve with regular training?
A Asthma is a tightening of the small breathing tubes in the lungs. The tubes are surrounded by muscle fibres to regulate air entry and exit, and may be triggered to contract by both external and internal stimuli. There is a slightly different trigger for every asthmatic, but allergies to animals, plants and chemicals act as triggers for many sufferers.
In exercise-induced asthma (EIA), exercise produces changes in the lungs which your GP can measure using a peak flow test. Generally, the more severe the exercise the more likely it is that bronchospasm – a narrowing of the airways – will occur. If peak flow is reduced by more than 10 per cent by exercise, your GP will diagnose EIA.
The cause of EIA is unknown, though low air humidity and temperature may act as triggers. Conversely, inhaling warm humid air will lessen the chance of occurrence. When you breathe hard, the air is not warmed as it enters the lungs. This also increases the amount of mucous, which is a further obstruction to exhaled air.
Training improves EIA but cannot prevent it. Aerobic exercise increases the ability to take in and use oxygen, and improves the expansion of the breathing tubes, reducing the severity of EIA when it does occur. If you exercise for more than eight minutes the EIA will not worsen beyond that time.
Inhaled medications, usually a steroid, can prevent bronchospasm. These are usually taken twice a day, but if you feel an attack coming on, a quick-acting inhaler, called a beta 2 agonist, will ward off bronchospasm for up to six hours. EIA need not hinder your running provided you learn to master it.
— Patrick Milroy, RW Medical Adviser