Exercise as it relates to Disease/Exercise induced asthma

Asthma is a common chronic respiratory disease. People who have asthma have sensitive airways leading to their lungs, often making it harder to breathe.

Three factors cause the difficulty to breathe:
 * The inside of the airway becomes red and inflamed
 * Extra mucus built up inside the airway which can block the airways, this extra mucus can influence the narrowing of the airways;
 * Muscles around the airways tighten up closing the airway called “bronchoconstriction”.

Over 1 in 10 people in Australia have Asthma compared to 1 in 12 people in the US. An international estimate of Asthma sufferers is approximately 300 million.

There are two main types of Asthma Intermittent and Persistent, one being more severe than the other. Intermittent Asthma means that sufferers don’t posses symptoms the whole time and they have mild to severe asthma attacks from time to time. This can be well maintained with medication. Persistent Asthma is more severe and less common, sufferers have frequent symptoms and attacks.

Triggers
One form of the condition is Exercise Induced Asthma (EIA), which is triggered either before, during or after exercise. Exercise is not the only trigger for an asthma attack, others include: Asthma attacks are all treated the same regardless of how severe a persons asthma condition.
 * Allergies, such as dust, pollens, grasses, lawn cuttings, cat or dog etc.
 * Cigarette smoke
 * Cold air
 * Hot dry air
 * Certain medications and irritants, such as aspirin
 * Emotion, including laughter
 * Chest infections
 * Stress

Asthma effects on Exercise
If a person suffers from EIA, also known as Exercise Induced Bronchoconstriction (EIB), then it can reduce their capability to compete in physical activities. Often EIA wrongly diagnosed as a lack of fitness, and therefore exercise at a disadvantage without the proper treatments. EIA and EIB are more often over-diagnosed than under-diagnosed, of the 266 athletes in the 2004 British Olympic team, asthma was misdiagnosed in 21% but undiagnosed in 2.6%.

Symptoms
Symptoms can occur within 5-20 mins after starting exercise or 5-10 upon completing brief exercise bouts.
 * Coughing
 * Tightness of the chest
 * Wheezing
 * Unusual fatigue while exercising
 * Shortness of breath when exercising

Second Wave
The 'Second Wave' is an interesting phenomenon associated with asthma attacks and EIA. Occasionally symptoms of an asthma attack will start to get better and then after a short period of time can begin to worsen again, this can be because severe stress has been placed on the airway and it has become more sensitive to irritants and 'triggers'. A 'second wave' attack can last from anywhere between a few hours to several days and in some cases requires medical attention.

Treatment of Exercise Induced Asthma
There is debate on whether or not the cause of EIA is respiratory heat loss or water loss. Recent research generally accepts water loss as playing the major role, because air is normally breathed in through the nose and warmed and moistened, which doesnt occur when breathed in though the mouth (ie. During exercise). Because it is a chronic disease EIA treatment can take a long time. EIA is treated in two ways, via use of a medication or through the use of exercise. Generally medication is always used in the treatment of EIA, however the use/prescription of exercise is dependant on the severity of the condition. Most of the time it is easy to prescribe exercise to children with an asthmatic condition, however as people get older it becomes harder.

In general it is thought that the most effective treatment of EIA or EIB is Medications and exercise be used in conjunction with each other, which allows majority of EIA sufferer to live a normal, healthy and active lifestyle.

Exercise Recommendations
It is always important to take into consideration the training environment, and in all cases avoid the presence of 'triggers' and allergens. Swimming was previously thought to be the most effective exercise for the management of asthma, while it is still highly recommended, there is now debate that swimming in an indoor environment may adversely affect a persons asthmatic condition rather than assist it, this is because of the gases release from the chemicals in the water. Exercise is split into two categories high risk and low risk activities, obviously those with more severe asthmatic conditions should seek participation in only the low risk exercise. Its also important to note that regardless of the level of risk associated with the activity it is recommended that an asthma 'action plan' be prepared in case of emergency, just having this plan can turn a high risk activity into a relatively low risk.

Exercise should be aiming to improve cardiorespiratory fitness without placing the participant in jeopardy of having an asthma attack. Recommended levels of exercise are around an intensity of 40-60% of one's Oxygen Uptake (VO2max). This should be completed 3-5 times a week for between 20–60 minutes, the very unfit should be limited to 20 minutes but aim for obtaining 30 minutes minimum.

Further Information
Asthma Australia: Exercise Induced Asthma

Sports Medicine Australia: Asthma Management

National Heart Blood and Lung Institute:Asthma Guidelines(American NHLBI) and Treaments

Web MD:Medications for Treatment of Asthma

Youtube link: Asthma Overview

Nutritional Information - Mickleborough, TD, Head, SK & Lindley, MR 2011, 'Exercise-Induced Asthma: Nutritional Management', Current Sports Medicine Reports (American College of Sports Medicine), vol. 10, no. 4, pp. 197–202