Exercise as it relates to Disease/The effects of moderate-intensity aerobic exercise on inactive adults with asthma

This Wikibooks page is a critical appraisal of the journal article "Feasibility of exercising adults with asthma: a randomized pilot study" by Boyd et al. (2012).

What is the background to this research?
Asthma is a chronic disorder of the airways that causes excessive inflammation in response to everyday stimuli, and may be especially triggered by allergens and viral respiratory infections. Over 350 million people worldwide are living with asthma and experience symptoms such as chest tightness, dyspnea, coughing, wheezing, and shortness of breath or airflow limitation. Asthma can have various negative effects on an individual's daily life, and when uncontrolled may lead to exercise intolerance, partly due to fear of triggering symptoms. As such, physical inactivity is common among asthma sufferers, particularly those with severe asthma, which has its own negative effects.

There have been numerous studies investigating the effectiveness of various types of exercise on management of asthma symptoms, and the general consensus is that exercise is beneficial in asthma management. It would be advantageous to determine what specific types of exercise, such as moderate-intensity aerobic exercise, can help manage asthma symptoms. The aim of the present study was to determine the effect of moderate-intensity aerobic exercise on cellular, molecular, and functional measures in inactive adults with mild-to-moderate asthma.

Where is the research from?
Most of the authors of this article work in various departments at the University of Alabama at Birmingham (UAB), out of which this study was conducted. Two of the authors worked at the UAB Lung Health Center, from which the subjects of this study were recruited. One author, Dr. M Dransfield, received consulting fees from GlaxoSmithKline, however, had little involvement in the interpretation of results. There may have been some bias towards producing positive outcomes for this study.

This article was published in Allergy, Asthma & Clinical Immunology, the official journal of the Canadian Society of Allergy and Clinical Immunology (CSACI).

What kind of research was this?
This was a randomized pilot study where the participants were randomly assigned to either the exercise group or the control group in order to avoid biased interpretation of the results. As it was a pilot study, it was performed in preparation for larger study that will more accurately determine the effect of moderate-intensity aerobic exercise on cellular, molecular, and functional measures in adults with asthma. This type of study is considered to be the standard for assessing a given intervention, and will allow the authors to test the viability of a larger scale study of the same intervention.

What did the research involve?
19 adults with mild-moderate asthma and no history of regular exercise in the previous six months were chosen from the UAB Lung Health Center’s Asthma Clinical Research Database. The participants were randomly assigned to either the "usual care" treatment group or the "usual care with moderate-intensity aerobic exercise" treatment group. All participants were issued pillow cases and mattress protectors to reduce allergen exposure, and the exercise group was issued a free three-month pass to a local exercise facility to encourage them to complete the program. These strategies were included to minimize differences in the two groups that could affect the outcome, such as asthma flare-ups due to allergens. All participants underwent a short educational briefing on asthma and good health practices at the commencement of the study.

The exercise intervention consisted of three thirty-minute sessions per week for twelve weeks where the participants walked at a steady-state of 60-75% of their maximum heart rate. Each session began and finished with a five-minute warm-up and cool-down. Pre- and post-intervention tests of maximum heart rate (HR max ) and maximal oxygen uptake in one minute (VO 2max ) in the exercise group were taken to assess for any improvements over the duration of the intervention. The participants kept a weekly exercise diary that recorded their exercise sessions, use of the pillow cases and mattress protector, good health practices, and asthma symptoms related to the exercise program.

Blood and nasal lavage samples were taken before and after the intervention to test for pro-inflammatory markers and differential cells, as well as serum ECP. Lung capacity tests were also performed. Finally, the participants undertook the Juniper Asthma Control Questionnaire (ACQ) pre- and post-intervention to determine any small changes in asthma control.

Whilst the measures taken during the study were useful in determining improvements in asthma management, for a larger study population these measures would be highly time-consuming. The twelve-week intervention may not have been long enough to produce statistically relevant results either, as most outcome measures had not changed significantly enough during that time.

What were the basic results?
The participants in the exercise group experienced improvements in asthma control after the intervention according to the ACQ. There were no significant changes detected in serum ECP, differential cells, pro-inflammatory markers, or during the lung capacity tests. The fitness levels of the participants did improve significantly, particularly their VO 2peak and total treadmill time. Peak heart rate and respiratory exchange ratio also improved among the exercise group.

These results suggest that a moderate-intensity aerobic training program has the potential to improve asthma control and aerobic fitness in asthmatic adults. However, the study did not present any significant differences in most of the outcome measures. The authors hope that a larger study will achieve the desired results.

What conclusions can we take from this research?
This study highlights that moderate-intensity walking sessions of thirty-minutes a day, three times per week, have the capacity to reduce asthma symptoms and improve aerobic fitness in sedentary adults with asthma. While the results may not have demonstrated all of the changes the authors expected, it did achieve its main purpose, which was to test the feasibility of such an intervention for a larger population.

Further studies on the effects of exercise on asthma management from 2015, 2018 and 2021 in varying populations all found that their exercise intervention had some beneficial effect on the management of asthma symptoms. These results confirm the conclusions from the current study, suggesting that exercise in general has positive impacts on asthma management.

Practical advice
To combat inactivity caused by fear of triggering asthma symptoms, a low-risk, moderate-intensity walking program may be incorporated. It has been shown in many studies that exercise in general is advantageous in many aspects of life, and may be useful in controlling and limiting asthma symptoms.

For adults with mild-moderate asthma who are not currently exercising regularly, a moderate-intensity walking program could be used to manage their asthma and improve their aerobic fitness. To achieve these results, at least thirty-minutes of walking at 60-75% of their HR max three times a week is required. This type of exercise has not been confirmed to be appropriate for individuals with severe asthma during this study.

Asthmatics that also suffer from other major illnesses such as severe hypertension, stroke, coronary artery disease or any other conditions that may impact their ability to exercise should consult their doctor as to whether this type of exercise may be appropriate for them.

Further information/resources

 * Getting active when you have asthma
 * Safely Exercising with Asthma
 * 7 Tips to Overcome Asthma When You Exercise
 * Exercise for people living with asthma
 * All About Asthma and Exercise