What Is Asthma?
Asthma is a chronic inflammatory disorder of the airway. The chronic inflammation is associated with airway ‘hyperresponsiveness’ that leads to episodes of wheezing, breathlessness, chest tightness and coughing. These episodes are commonly associated with obstruction to airflow that is mostly reversible either spontaneously or with treatment and can be highly variable.
The airways may be narrowed by one or more of the following:
- Contraction of the airways smooth muscle (bronchoconstriction), swelling of the airways (oedema).
- Increased production of mucus alongside inflammation.
- Thickening of the airways (remodelling) due to structural changes – these are not completely reversible.
The severity can range from occasional episodes of difficulty breathing to frequent life-threatening bouts of airways obstruction.
A large proportion of asthmatics will experience bronchoconstriction provoked by exercise, termed exercise induced asthma (EIA).
Because breathlessness is normal after all but low intensity exercise, many asthmatics are unaware when EIB is developed post exercise. The assumption can be made that their dyspnoea (shortness of breath) is poor fitness, they often fail to seek medical advice, and perform physically at a disadvantage because of a lack of appropriate medication. Because of asthma and EIB, many asthmatics avoid exercise which results in low aerobic fitness and at times, obesity
Who Is It Commonly Seen In?
In Australia, there are over 2 million asthmatics including:
- 1 in 7 primary school children
- 1 in 8 teenagers
- 1 in 9 adults
- 385 Australians died of asthma in 2007
The prevalence of asthma is generally highest in the first 10 years of life, it arises amongst members of all races, and the initial bout can occur at any age. It is more common in boys than girls at a 3:2 ratio and in older women more so than older men
Many triggers of asthma including: allergens, cold air, exercise, infections, pollutants, and some drugs.
An ‘Asthma Action Plan’ is a set of instructions developed for each asthmatic assisting them to identify worsening asthma symptoms, quickly apply treatment as the plan instructs and seek appropriate medical assistance. The individual and their family must understand how to provide asthma first-aid. It is recommended that physicians also develop an “EIB Action Plan” in addition to the general “Asthma Action Plan” for their patients and emphasize that it is difficult to prevent EIB if asthma is not adequately controlled.
As part of the Asthma Action Plan, it is recommended that asthmatics purchase an inexpensive peak flow meter or FEV1 (forced expiratory volume) meter and monitor their lung function on a regular basis. Change in peak flow values or FEV1 values may signal the need to modify dosage or type of medication.
A major benefit of regular exercise for asthmatics is improved aerobic fitness (VO2 max) which means that a given level of exercise can be carried out at a reduced percentage of his or her VO2 max, so providing a lesser stimulus for EIB.
if an asthmatic exercises with significant airways constriction, exercise performance will be impaired.
A progressive multifactorial warm-up may allow a ‘refractory period’ that may be a useful preventative time where the asthmatic has reduced chance of developing EIB.
Progressive increase in intensity as fitness improves is vital, and to stress the aerobic system but not strain. Intensity of 40-60% of Oxygen Uptake Reserve is recommended (V02R) or 6/10 RPE.
Duration & Frequency
30-60 minutes 3-5 x per week is sufficient, starting with no more than 20 minutes before progression.
Following low level of walking and jogging type exercise, and later continuous running, one can progress to high intensity interval training (HIIT), using training intervals of 10–30 s followed by 30–90 s rest periods. Many team sports are ideal, as they require an intermittent pattern of energy expenditure.
- It is important to exercise only if controller and preventive medications have been administered pre-exercise
- The availability of a peak flow meter or FEV1 meter is prudent and if the peak flow value or FEV1 value is less than 75% of normal, exercise is unwise.
- Performing vigorous physical activities while the airways are significantly constricted can lead to a severe drop in the arterial oxygen saturation, accumulation of carbon dioxide and hyperinflation of the lungs with an increased residual volume. Severe dyspnoea and worsening of the bronchoconstriction with fatigue of the respiratory muscles may ensue. Death from asthma during exercise is rare but can occur.
- Scuba diving is a sport that poses significant dangers for all participants and this is especially true for asthmatics who are generally advised to avoid it
- Road cyclists and runners are at risk of developing airway hyperresponsiveness due to inspiring significant quantities particulate matter from vehicle emission