Exercise as it relates to Disease/Altitude training and asthma
Asthma is a chronic respiratory disease that affects approximately 300 thousand people worldwide, with numbers seemingly on the rise. The chronic disease is characterised by narrowing of airways from muscular contractions (bronchoconstriction), mucus hypersecretion, episodic shortness of breath and chronic inflammation of the bronchial membranes. The chronic inflammation is associated with airway hyper-responsiveness (AHR) that causes recurrent wheezing, breathlessness, tightness of chest and coughing  particularly during the night, in the early morning or during vigorous exercise. Causes of asthma are commonly termed atopic, meaning they stem from childhood or adolescence and can be traced back to particular triggers such as pollen, cold ambient temperatures or certain foods, or non-atopic, meaning they occur as a result of triggers that are not necessarily the actual cause. Little research has been done into the possible pros or cons in exercising at altitude with asthma but potential insight may be drawn from existing literature on the concept.
Exercise Induced Asthma
Exercise induced asthma (EIA) is classified as the temporary constricting of the respiratory airways during or after bouts of intensive exercise, particularly those conducted outdoors where the air temperature and humidity can vary greatly, creating heightened stress on the respiratory system. Research from recent Olympic Games has found that exercise induced asthma (EIA) amongst high end athletes is becoming more prevalent. A recent study into elite sports and the rates of asthma found that 45% of road cyclists and mountain bikers displayed EIA (as did high quantities of swimmers and cold weather endurance athletes) The common denominator between the statistics is that aerobic endurance exercises returns more asthmatic results. This increased occurrence of EIA is leading to a heightened percentage of athletes using bronchial dilator medications, particularly in those endurance sports such as cycling (15.4%), triathlon and swimming.
Contemporary Asthma Treatment
The management of asthma today is constantly improving but frequently requires a tailored treatment plan consisting on various combinations of common treatments. It is has been found that women are more likely to suffer from asthma and encounter treatment difficulties as a result of their hormonal changes and it for this reason that tailored treatment plans are commonly required. The following are a list of common treatments
- Preventer Medictions (Corticosteroid inhalers for long term prevention)
- Relievers (Short acting beta-agonist inhalers for quick relief)
- Nebulisers (Vaporised liquid medication for inhalation)
The known benefits of aerobic exercise
There are known physiological and psychological benefits of aerobic exercise for asthmatic sufferers. As asthma is consistently linked to abnormalities in temperature and humidity of respirated air, along with the sheer mechanical stress of a raised ventilation rate, training at a wide variety of intensities has been shown to illicit various positive changes in physiology. The general concensise given by empirical literature on the topic have found the following:
- Improved peek expiratory flow (PEF)
- Improved forced expiatory volume in one second (FEV1)
- Improved forced expiratory flow at 25-75% vital capacity (FEF25-75%)
- Decreased airway inflammation
- Fewer symptomatic flair-ups
- Fewer emergency department visits
- Decreased reporting of anxiety and depression
The pros and Cons of Altitude on asthma
Although limited research has been done in the area of altitude and its effects on asthma control and treatment, some research has found various potential benefits and risks associated with altitude exposure. The most common element noted in these studies was that of allergen avoidance. Our respiratory system is uniquely susceptible to contamination via the air we breath, and the recently observed increase in asthma is western populations has been closely attributed to the increase in air pollutants and allergens.
|Avoidance of Pollutants||The relative concentration of pollutants and allergens is significantly decreased compared to lower altitudes, minimising the risk of airborn asthmatic triggers affecting respiration.|
|Increased UV Exposure||Evidence suggests Vitamin-D levels are linked with severity of immune responses with asthma. Increased exposure allows vitamin-D levels to remain elevated.|
|Lower Air Viscosity||The lower air density decreases the respiratory resistance allowing for an increases in respiratory flow rates, decreasing the overall mechanical strain on respiratory system.|
|Decreased Pulmonary Ventilation (VE)||Lower VE at a given work rate allows an overall improvement in respiratory efficiency, reducing the stresses of elevated ventilation.|
|Reduction in Nitric Oxide (NO) expiration||Nitric oxide has been linked to the severity of respiratory inflammation. Lower levels of expired NO correlates with a decreased inflammatory response.|
|Hyperventilation Risk||The risk of decreased O2 reaching working muscles (termed hypoxia) can lead to hyperventilation if not closely monitored. Hyperventilation would therefore increase the mechanical stress of elevated ventilation.|
|Bronchial hyper-responsiveness (BHR) can increase||The mechanical stress that can come about as a result of hyperventilation has been seen to stimulate BHR, leading to the narrowing of airways as a result of muscular contraction.|
|EIA still present in elite athletes||Regardless of the level of exposure to high altitude and the associated positive responses associated with this, elite athletes still display EIA frequently, suggesting that classic asthma and EIA are different in their mechanisms.|
By reading recent evidence surrounding the effects of altitude training and asthma, it is clear that more research is required to gain a better understanding of concept. There are, however signs that training at high altitudes for sufferers of classic atopic asthma may benefit their quality of life and allow for an improvement of exercise capacity (provided the programs are tailored and instructed by professionals). Evidence appears to be weak surrounding the possible benefits of altitude training for elite athletes who already have a well developed respiratory system. The prevalence of EIA in elite populations suggests pharmacological interventions involving preventers and relievers that use corticosteroids to control symptoms are more beneficial than training at altitude.
Livestrong: Altitude Training
Sports Medicine Australia
Asthma Foundation of New South Wales
National Asthma Council
Australian Asthma Handbook
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