1. Asthma
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Asthma is a chronic respiratory disease characterized by airway inflammation and hyper-responsive bronchoconstriction.
Although there is no cure for asthma, it can often be controlled with daily medication and by the avoidance of triggers.
Symptoms of asthma include the following:
Wheezing from peripheral airways
Cough
Chest tightness
Shortness of breath
Excess sputum production (sometimes)
Symptoms are often worse at night and may be related to a specific allergen, air pollutant, or cold or dry air and as such may be seasonal. Symptoms are often triggered by exercise, in the condition known as exercise-induced bronchospasm (EIB), which typically occurs in exercise lasting longer than approximately 6 min

2. Basic Pathophysiology of Asthma VIDEO
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Basic Pathophysiology of Asthma
VIDEO
There are three basic phenotypes of asthma, which are characterized by their primary pathophysiological traits, but phenotypes often overlap

3. Management and Medications
Asthma
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Management and Medications
Key steps in the management of asthma include the proper diagnosis of symptoms, particularly exercise-associated symptoms, as there are many possible causes of dyspnea during exercise.
Once someone has been properly diagnosed with asthma, the mainstay of preventing asthma attacks is to avoid any environmental irritants that precipitate an attack.
In someone with apparent asthma (whether eosinophilic or neutrophilic), symptoms of bronchial hyper-responsiveness (BHR) suggest that control of the underlying inflammation is inadequate.
Thus, the first-line therapy for a confirmed diagnosis of asthma is inhaled corticosteroids, which are used either alone or in combination with other medications. (See Table 17.2 – FYI)
Inhaled corticosteroids decrease airway inflammation and attenuate exercise-related BHR, providing bronchial protection during exercise in up to 60% of persons with asthma.

4. Asthma Medications - FYI
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Asthma Medications - FYI
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Additional daily medications such as short- or long-acting β2-adrenergic receptor agonists (SABAs and LABAs, respectively), perhaps in combination with a leukotriene receptor antagonist, may be needed as add-on therapy to inhaled corticosteroids.

5. Effects on the Exercise Response
Asthma
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Effects on the Exercise Response
Approximately 90% of people with asthma are symptomatic during or after exercise, and EIB is most severe in those with uncontrolled airway inflammation.
The subgroup of individuals who react to exercise but do not have inflammatory asthma (EIB without apparent asthma) can be symptomatic depending on the exercise and environmental air quality.
Several factors determine whether EIB is severe enough to limit exercise:
The degree of chronic inflammation
Airway responsiveness
Mode of exercise (e.g., constant or interval)
Intensity and duration of exercise
During exercise, EIB causes “air trapping” and can cause restricted exercise ventilation limiting exercise capacity

6. Effects on the Exercise Response
Asthma
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Effects on the Exercise Response
The classic EIB response observed during a 6- to 8-min exercise bout is bronchodilation during exercise and bronchoconstriction after exercise. When tidal volume decreases after exercise, bronchoconstrictive influences dominate airway function.
During prolonged steady-state exercise, the bronchodilation within the first six minutes of exercise is followed by a steady decline in airway function.
During interval-type exercise, of alternating moderate and light intensity, expiratory flows gradually decrease over time but show improvement in airway function during the moderate-intensity period with deterioration during the light-intensity period
High-intensity exercise may provoke EIB, particularly when performed in an unfavorable environment ( cold air, dry air, airborne irritant particulates)

7. Effects of Exercise Training
Asthma
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Effects of Exercise Training
Regular exercise can reduce the severity of EIB and increase the exercise level at which EIB occurs. This is probably because of an increase in ventilatory threshold as a consequence of regular training.
Exercise alone does not improve airway inflammation. Exercise training does have a modest beneficial effect on asthma itself, comprising the following:
Decrease in medication usage
Decrease in intensity of exacerbations
Decrease in post-exercise falls in lung function
Increase in the number of symptom free days

8. Effects of Exercise Training
Asthma
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Effects of Exercise Training
The prevalence of EIB and asthma is higher in cold weather athletes, suggesting that long-term exposure to pollutants or cold, dry air at high ventilation rates damages airways.
The EIB response may vary with seasonal climate and allergen loads. Approximately half of individuals suffering from EIB are refractory to a second episode of EIB two to three hours after the initial episode.
Aerobic exercise training reduces migration of antigen-specific Helper T cells to the lung. Exercise training improves asthma-related quality of life (days without asthma symptoms)

9. Recommendations for Exercise Testing
Asthma
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Recommendations for Exercise Testing
Maximal exercise testing can be performed to measure physiological responses and monitor the status of individuals with asthma or EIB, but should be performed only if the asthma is well controlled or a SABA is used as prophylaxis.
Contraindications to exercise testing in asthma include :
Baseline FEV1 <70% of predicted, or <1.5 L
Significant bronchodilation (>12% FEV1) in response to a SABA
History of cardiovascular problems
History of severe hypertension
Known aneurysm
Conditions that affect the ability to perform a challenge test (e.g., costochondritis, chest injury, recent sternotomy

10. Recommendations for Exercise Programming
Asthma
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Recommendations for Exercise Programming
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Persons with asthma or EIB without apparent asthma should have their condition controlled, then undergo a challenge test and be subsequently referred to an exercise program. Many will already be active in sports and won’t need an exercise prescription.
Having asthma or EIB does not preclude one from regular exercise or participation in sports; in fact, a high prevalence has been shown among elite and Olympic athletes.
When asthma is well controlled, exercise programming should be dictated by other chronic conditions.
Major Factors and Tips for Managing Exercise-Induced Asthma
People should undergo a bronchial challenge test before beginning an exercise program.
Severity of disease and level of control achieved should be known, and the response to exercise and effect of pre-exercise treatment A warm-up consisting of interval-type exercise may attenuate the EIB response
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