f you have exercise-induced asthma your airways become irritated and narrow during or straight after exercise, so that it’s difficult to breathe. These days doctors tend to call it ‘exercise-induced bronchoconstriction’ (EIB) because strictly speaking it’s a different condition to asthma, even though the symptoms are pretty much the same.
It’s thought that 5-20% of people have EIB. It affects children and adults at all levels of sporting ability. About nine out of 10 people with EIB have asthma as well. It’s difficult to know for sure how many people have EIB without asthma because the symptoms are largely indistinguishable. The picture is further confused by the fact that exercise is a trigger for some people with asthma.
Sadly, children with EIB can have a reduced quality of life and emotional wellbeing.
Exercise-induced asthma causes and triggers
The cause of exercise-induced bronchoconstriction is dry air breathed in during exercise. When you breathe air that is drier than the air already in your body, your airways become dehydrated, which leads to muscle contraction and excess mucus.
Exercise-induced asthma triggers also include:
- Low air temperature (although it may simply be that cold air is drier than warm air).
- Irritants (allergens) in the air, such as environmental pollution, pollen or, in indoor sports halls and gyms, perfume, cleaners, chemicals, paint, new equipment or carpet.
- Viral respiratory infections.
Exercise-induced asthma signs and symptoms
Exercise-induced asthma symptoms are similar to those of asthma and include:
- A feeling of tightness in your chest
- Shortness of breath
- Producing excessive mucus
- Feeling unfit even though you know you’re in good physical shape
- Chest pain, though this is rare.
Signs and symptoms commonly appear within two to five minutes of exercising, reaching a peak after about 10 minutes. Within about an hour the symptoms have usually disappeared.
You’re more likely to have EIB if you:
- Have asthma that is poorly controlled
- Have severe asthma
- Have a close relative with asthma or wheeze
- Have an allergy such as hay fever
- Are a high-performance or endurance athlete. Up to seven out of 10 elite or Olympic sportspeople are estimated to have EIB, depending on their sport
- Are a child, especially if you live in a town or city.
How to diagnose exercise-induced asthma?
If you think you may have exercise-induced asthma, you should make an appointment to see your doctor. Your doctor will ask you about your symptoms and when they happen and may use exercise testing to detect evidence of bronchoconstriction. These measure changes in your lung function after exercise, as follows:
- Lung tests: using spirometry to measure your lung function before and five, 10, 15 and 30 minutes after exercise.
- Exercise challenge tests: monitoring your peak flow before and after your normal exercise – you might be asked to do this yourself over a few weeks at home.
- Alternative challenge tests: You may be asked to exercise intensively under supervision at the same time as challenging your lungs by breathing dry air through a facemask, by inhaling methacholine or by hyperventilating. This is called bronchoprovocation testing. Spirometry will be used to measure your lung function before and after.
If these tests confirm bronchoconstriction, your doctor will need to decide whether you have:
- poorly controlled asthma that is triggered by exercise
- well-controlled asthma with exercise-induced bronchoconstriction
- exercise-induced bronchoconstriction.
There is an overlap and misdiagnosis in this area. How you respond to treatment will give clues to the diagnosis.
Learn more about how asthma is diagnosed.
Exercise-induced asthma or out of shape?
Symptoms similar to those of exercise-induced asthma can be caused by exercising when out of shape. Your doctor will consider this during your initial appointment and may conduct or request other tests to rule this out. Other conditions with similar symptoms that your doctor may consider include over-exercising, vocal cord problems, breathing problems, habitual cough and heart problems.
If you have a loud wheeze when breathing in (not out), you may have exercise-induced laryngeal obstruction (EILO) . EILO is common in adolescents and athletes. Unlike exercise-induced bronchoconstriction and asthma, EILO doesn’t respond to asthma medications.
Should I stop exercising?
You should not stop exercising if you have exercise-induced bronchoconstriction. Regular exercise is an important part of a healthy lifestyle and has many benefits, especially if you have asthma. Ask your doctor for advice on how to exercise and manage your symptoms.
Exercises for people with asthma
Some exercises and sports are better for you than others if you have exercise-induced bronchoconstriction or asthma. Activities that need short bursts of energy are less likely to induce symptoms, such as:
- Hiking and walking
- Leisure cycling
- Cricket or baseball.
It’s best to avoid sports that demand continuous exertion, such as:
Winter sports can be especially challenging and cause symptoms because of the cold, dry air at that time of year – skiing, snowboarding, ice skating, ice hockey etc
Swimming can be fine because the warm, humid pool environment does not irritate the airways. However you may find that chlorine or other water-additives may trigger your symptoms so try different pools if that affects you.
Your doctor or nurse can advise the best ways to manage your symptoms when exercising. This may include using breathing exercises or avoiding exercise in certain climates.
If you have underlying asthma that is made worse by exercise, your doctor or asthma nurse will check that you’re taking your asthma long-term preventer medication regularly and with the correct inhaler technique. Managing your asthma optimally so that it’s well-controlled can be all that’s necessary to avoid problems when you exercise.
If you still get symptoms when you exercise you’ll be prescribed a short-term reliever medication to take before you exercise as well.
If you have exercise-induced bronchoconstriction (EIB) without asthma – that is, you don’t have asthma symptoms at any other time – the first-choice medicine is a short-term reliever inhaler to use immediately before you start exercising. You may not need a daily preventer as well.
The following short-term and long-term treatments have been shown to protect effectively against exercise-induced asthma or EIB.
- Inhaled short-acting beta-2-agoists (SABA) are bronchodilators that act quickly and keep symptoms at bay for two to four hours. Take 15 to 30 minutes before you exercise and as needed.
- Alternatively a combination of a long-acting beta-2-agoist (LABA) and a corticosteroid can be inhaled 30 to 60 minutes before you exercise. This should prevent symptoms for up to 12 hours. You can take this only once in a 12-hour period.
- Inhaled corticosteroids (anti-inflammatories) – are used daily to reduce the inflammation and sensitivity of the airways, so preventing the symptoms of EIB.
- A leukotriene receptor antagonist (LTRA) can be taken in the form of a daily tablet to prevent symptoms that accompany exercise.
- Theophyllines – a daily tablet preventer.
- Sodium cromoglycate or nedocromil sodium – daily tablet preventer.
Tips to manage and keep asthma under control
You can reduce or prevent exercise-induced asthma symptoms in you or your child by following the advice below:
- Warm up gently for about 15 minutes before starting intense physical exercise and always cool down after
- In cold weather, cover your nose and mouth with a scarf or facemask to protect your lungs from the cold air
- Breathe in through your nose to warm and moisten the cold air before it hits your lungs
- If you have underlying asthma keep it well-controlled at all times and ensure you have an up to date asthma action plan
- Avoid triggers that you or your doctor have identified – you may need to change your sport or where you exercise
- Keep a record of how often you use your SABA inhaler and review this with your doctor or asthma nurse regularly (at least once a year)
- If your child has EIB, tell PE teachers and carers about the importance of warm-ups, the signs of EIB and how/when your child should use their inhaler
Some people also recommend taking vitamin C and vitamin E dietary supplements. However there’s not enough evidence that these have any beneficial effect on asthma or exercise-induced bronchoconstriction.