Exercise as it relates to Disease/Can physical activity prevent asthma as we age?

This is an analysis of the journal article, "Physical fitness and amount of Asthma and Asthma-like symptoms from childhood to adulthood" by Guldberg-moller et al(1).

What is the background to the research?
Asthma is a chronic disease which currently has no cure or no definite causes. It is a disease of the airways, where a trigger can cause the airways to constrict(2). A Danish study looked at the potential benefits of physical fitness during childhood in preventing Asthma later in life. The aim of the study was to determine if there was a link between levels of physical activity and the development of Asthma and Asthma-like symptoms.

The study is based on the idea that there is a high prevalence of Asthma in obese individuals. Although there is no definite link between obesity and asthma, a contributing factor to being obese is a lack of physical activity(1,3). The researchers suggest that the cause of Asthma in obese individuals is due to a lack of physical activity.

Where is the research from?
The research was conducted in Denmark. The subjects were school children from 41 different schools in the Odense region. The findings were published online in May 2014 and in The Clinical Respiratory Journal in July 2015.

What kind of research was this?
The research was a longitudinal study conducted over a period of 20 years. The subjects went through physical fitness testing and answered questionnaires at the ages of 9, 15, 20 and 29. The fitness tests were used as an indication of physical activity levels while the questionnaire was used to determine if the subjects exhibited Asthma symptoms.

What did the research involve?
The aim of the study was to determine whether physical activity is able to prevent asthma as we age. The study began with 1369 subjects but only 28% of the subjects were involved in all four tests, the researchers believed that this provided sufficient data. The subjects went through physical fitness tests and answered questionnaires.

For the fitness tests, subjects had to complete a maximal progressive exercise test on a cycle ergometer. This involved exercising for five three minute periods, with the work load being increased at the end of each interval. The work load was determined by the subject’s weight and responses to the questionnaire. The subjects needed to reach their maximal effort for their results to be included. Maximal effort was defined as being 85% of the subject’s maximum heart rate, calculated from 220 minus the person’s age. From this test maximum oxygen uptake was measured and used as an indicator of physical fitness. Lung function was also measured prior to exercise. For the ages of 9 and 15 a spirometer was used and for the ages of 20 and 29 a Pheumotachograph was used. Two tests were conducted and results were recorded if they were within 5% of each other. In the questionnaire subjects were asked a variety of questions relating to, whether they had been diagnosed with asthma by a doctor, whether they presented with asthma like symptoms and questions in relation to their smoking status. The questions changed depending on the age group. Data was not collected on the amount or type of physical activity that the subjects did.

What were the basic results?
The research showed that there was a link between having low levels of physical fitness during childhood and having a higher risk of developing Asthma during adulthood. There was a decrease in fitness levels from the age of 9 to 29 and higher rates of Asthma and Asthma-like symptoms, there were higher rates of Asthma-like symptoms over physician diagnosed Asthma. There was no indication that having a low level of physical fitness at the age of nine would lead to Asthma symptoms at the age of fifteen. A number of covariates were taken into consideration when analysing the results, including, gender, smoking status, and being diagnosed with asthma at age 9.

How did the researchers interpret the results?
The study indicates that there is a relationship between physical activity during childhood and the development of Asthma later in life. Having a higher level of physical fitness during childhood can decrease the prevalence of Asthma and Asthma-like symptoms during adulthood. The researchers concluded that there is a 3% decreased risk of developing Asthma and 2% decreased risk of developing Asthma like symptoms if physical activity is undertaken during childhood. Additionally, the researchers suggest that the current increase in the prevalence of people suffering from Asthma may be due to a lack of physical activity during childhood.

What Conclusions should be taken away from this research?
The study shows a link between having higher physical fitness levels during childhood and having a reduced risk of developing Asthma during adulthood. This leads to the belief that being physically active during childhood with help with preventing Asthma later in life. The results are supported by a Finnish study where twins were subjected to a variety of lifestyle factors that could lead to Asthma (4). One of the lifestyle factors was being physically active compared to being sedentary. The results concluded that the twin that did physical activity had a reduced risk of developing Asthma than the twin that was sedentary. Recently in the western world there has been a decrease in the amount of physical activity that children participate in. The research suggests that this could be a contributing factor to the increased prevalence of Asthma. The researchers recommended that having a moderate to high level of physical fitness is the best was to reduce the risk of developing Asthma (1). There are limitations to the research. The data did not include the amount of physical activity that the subjects participated in or the type that they did. If this was included it could give more conclusive results about the amount and type of physical activity that needs to be done to help with the prevention of Asthma. The study did not take into consideration other lifestyle factors that may lead to asthma apart from smoking. This could have had an effect on the outcome of the results.

What are the implications of the research?
The results were conclusive in saying that physical activity during childhood is a protective factor against developing Asthma in adulthood. Due to the results being published and accessible to the public, it may encourage children to become more physically active. This could lead to multiple other health benefits such as reducing the risk of obesity or diabetes. In 2008-2009 the Australian government spent 655 million dollars on the treatment of Asthma (5). Since physical activity during childhood has been shown to reduce the risk of developing Asthma, it could be used as a preventative measure. The use of preventative measures has been shown to be a more cost effective way of treating chronic diseases therefore the expense of treating Asthma could be reduced(5).