Exercise as it relates to Disease/Exercise and diet as an intervention for non-obese asthma patients

This wikibooks page is a critical appraisal of the journal article "Effects of Exercise and Diet in Nonobese Asthma Patients—A Randomized Controlled Trial" by Toennesen.

What is the background to this research?
Asthma is a condition that affects the airways, restricting breathing with the potential to be fatal. The incidence of obesity and asthma coexisting within a patient is steadily rising, likely due to obesity being a known predisposing factor of asthma. Previous research has identified that changes in exercise and diet behaviour improved asthma control in an obese population but this was unknown if this was similar for a non-obese population. Whilst the majority of the Australian asthmatic population is obese, this study is important because there is still an unrepresented 30% that fall within a ‘normal’ BMI.

Another point of difference for this study, that separates itself from others, is its focus on high-intensity interval training (HIIT) rather than low to moderate-intensity exercise. This decision is justified by the study as it states a lack of research on this form of exercise as well as HIIT becoming increasingly popular for its "efficiency"

Where is the research from?
The study is conducted by an array of authors including Toennesen, Meteran, Hostrup, Wiem Geiker and Jensen. All listed authors have contributed to at least 3 different journal articles across a range of subjects. Namely, Hostrup has contributed to 20. This large input from experienced authors helps the credibility of this source.

However, the journal in which this article is published is not highly ranked on the Scimago Journal Ranking (SJR) system. With a rank of 1918th, it does not compare to some of the more prolific journals in its field. Whilst this ranking system is not perfect and is based largely on how often it is cited, it does provide some indication of how popular it is and therefore a rank this low can be considered significant. Although, the study was conducted in Amsterdam which, using the same ranking system, ranks 15th across the world which is notably high. Despite the data coming from the Netherlands, it is still applicable to Australians.

What kind of research was this?
The research method utilised within this study was a randomised control trial. These are believed to be the 'gold standard' in research as they reduce bias and allow for the examination of cause-effect relationships (but cannot be used to prove them). Random assignment was done via sealed envelopes which were generated by a computer. The researchers involved in collecting data were also blind to the random assignment of the four different groups, adding to its validity.

What did the research involve?
The study took participants aged 18-65 with specific BMI characteristics (between 20 and 30) and having both achieved a certain score on the Asthma Control Questionnaire (1.0 or more) and at least 1 positive diagnosis of variable airflow. Whilst BMI is a commonly used indicator of obesity, it is an indirect measure which can lead to misclassification. Anthropometric indicators such as relative fat mass, body shape index and body roundness index are some other potential measures which are beginning to emerge.

Participants were split randomly into four groups


 * Exercise group (8 weeks HIIT on indoor bikes 3 times per week).
 * Diet group (5 group counselling sessions in which they prepared food pertaining to a diet that was high in protein and low GI).
 * Exercise + diet group (followed both exercise and diet interventions).
 * Control group (No intervention)

An issue with this methodology, as with any behavioural intervention, is the potential for participants to behave uncharacteristically when being observed. This is known as the 'Hawthorne Effect' and, if incorrectly managed, can skew results.

What were the basic results?
Results showed a significant positive change in the Asthma Control Questionnaire (ACQ) for those in the diet and exercise group, however, there was no significant difference for participants in the exercise or diet groups. A meta-analysis testing the accuracy of the ACQ for measuring asthma control found some limitations and identified the Asthma Control Test (ACT) as better suited for clinical use. This may lead to a potential over-emphasis on the results provided, however, since the difference is significant and ACQ can still provide correct results there is still a chance that this intervention may be effective. NOTE. Values are mean ± SD

It is significant to note that other variables pertaining to asthma control and lung efficiency were measured, however, the greatest emphasis was placed on the ACQ score which is why the information pertaining to its accuracy is particularly relevant.

What conclusions can we take from this research?
This study is a good introduction to an area that is largely unexplored. Whilst it concluded that a combination of HIIT and diet is effective for improving asthma control, there is still more research that needs to go into the specificities of both the exercise and dietary components. Searching for similar articles provides very few results due to the large focus on the association between obesity and asthma leading to little comparable information. This makes the information in the study important but difficult to validate.

Practical advice
This research emphasises the importance of a balanced lifestyle. Identifies that a multifaceted approach to health is more effective than changing behaviour in a single aspect of health. Specifically, it identifies HIIT as the form of exercise that should be conducted to achieve the results that occurred in the study. This is a good outcome as HIIT is becoming a more popular form of exercise and is easily accessible both via internet tutorials or through an organisation like HIIT Republic.

As well as a specific exercise, a diet containing high-protein and low GI is recommended from the results gathered. Like the HIIT workouts, this type of diet can be easily researched, however, a limitation is that it can sometimes be difficult to filter through the information that may not be correct as everyone has access to the internet and is capable of putting anything online. Some further scientific study into specific meals and/or protocols to follow with this diet would be beneficial to those trying to take advantage of its positive outcome.

Further information/resources
Severe Asthma Toolkit

Asthma Australia

HIIT Republic Canberra

What is a High-Protein, Low-GI diet