Exercise as it relates to Disease/Effects of swimming on children with asthma

This is a critique of Jeng-Shing Wang and Wen-Ping Hung's (2009) article The effects of a swimming intervention for children with asthma for the purpose of a 'Wiki Assessment' in Semester 2, 2021 at the University of Canberra for the unit; Health, Disease and Exercise.

Background Research
Asthma is a common paediatric respiratory disease that effects an individual’s airways making it difficult for them to breathe. As of 2007, approximately 300 million people globally had asthma with prevalence increasing 50% per decade. Within the same year 11% of children 6 to 7 years and 14% of children 13 to 14 years had reported the prevalence of asthma. Studies have shown that swimming is unlikely to provoke an asthma attack and can help increase lung volume, breathing technique, physical and psychological development, muscle tone and general fitness.

This study uses pulmonary function tests (PFT) to determine whether there is an association between pulmonary function and children with asthma. At the time of publishing there was minimal information on this topic but has since expanded.

This study looks to analyse the effects of a 6-week swimming intervention on PTF, peak expiratory flow (PEF) monitoring and severity of asthma in 30 children with asthma.

Where is the research from?
The study was conducted by Jeng-Shing Wang and Wen-Ping Hung.

Wang is a highly experienced researcher, who has published numerous articles since 1995. He currently is a part of the Department of Medicine in Taipei Medical University and specialises in chronic obstructive pulmonary disease. Many of his articles address rising respiratory diseases however are generally reproductions of previous literature with minimal new findings.

This study appeared to be Hung’s first published article. He is a part of the Department of Physical Education, Kaohsiung Medical University in Kaohsiung, Taiwan. From research it appears he has not published any further articles.

What kind of research was this?
This study is a randomised controlled study, investigating the effects of a 6-week swimming intervention on PFT, PEF monitoring and the severity of asthma in 30 children with asthma. Individuals within the experimental group (n=15) participated in three, 50-minute sessions per week. Individuals within the controlled group (n=15) received no specific intervention.

What did the research involve?
Children between the ages of 7 and 12 years, diagnosed with asthma according to the American Thoracic Society (ATS) criteria were invited to partake in the study. 30 children were enrolled and separated into an experiment and controlled group. The experimental group consisted of 10 males and 5 females with an average age, height and weight of 10 years, 141cm and 41kg respectively. The controlled group consisted of 10 males and 5 females with an average age, height and weight of 10 years, 136cm and 36kg respectively. Participants partook in three 50 minutes sessions consisting of a 10-minute warm up including breathing exercises, 30 minutes swimming training and a 10-minute cool down with breathing exercises. Swimming training for beginners started with kicking and experienced swimmers, freestyle and breaststroke.

There are several limitations within this study. Within no post intervention feedback, the researchers will have limited evidence that the intervention effected participants outside physical test results. This means they may not be able to conclude if the intervention has a positive effect on the participants social, emotional or cognitive development. The study uses complex terminology and can be difficult to understand if you are not educated within the field. A firm knowledge on research statistics and interpretation are needed. Understanding of chi-squared tests, two-tailed student t-tests, power, p values, confidence intervals, standard deviation and z-scores will aid in interpretation of data.

What were the basic results?
The following results were concluded,

-       Significant improvement (P < 0.05) in post-intervention FEV1, FEF50, FEF25-75 in the experimental group compared with pre-intervention test results.

-       There was no significant difference in post-intervention PFT results when comparing the experimental and controlled group

-       No significant difference (P < 0.05) between groups in PEF at baseline (224 L/min) however, there was significant improvement in the experimental group after 3 weeks (300 L/min, P < 0.05) and 6 weeks (330 L/min, P < 0.01)

-       In the experimental group there was a significant improvement (P < 0.05) in post-intervention PEF compared with baseline, which was not seen in the control group

-       Post-intervention there was a significant improvement (P < 0.05) in the severity of asthma in the experimental group compared to the controlled group. This could not be confirmed as data was not shown

The results concluded that there is a significant difference between respiratory parameters and severity of asthma in a 6-week swimming intervention. However, there was no significant difference between PFT parameters and a 6-week swimming intervention

Within the study, some conclusions seem over-emphasised. Wang and Hung concluded that there was significant improvement in emergency room visits, rate of hospitalisations, days absent from school, chest deformity, snoring and doctors’ visits following the program, yet no data was collected on these aspects. There may have been a positive association between these variables and children with asthma but with no reported data it’s only an assumption.

What conclusions can we take from this research?
From the study we can conclude that swimming has a positive association with decreased risk of respiratory factors that induce asthma. During swimming, the high humidity of inspired air induces less airway mucus build up as well as the high hydrostatic pressure to reduce expiratory effort and work. Through frequent contact with health professionals there was an improvement in asthma awareness and asthma control which saw an increase in compliance with asthmatic treatment. The results align with other literature.

PFT parameters at the conclusion of the intervention did not differ between the controlled and experimental group suggesting that there is no association with asthma. This may be due to the physical characteristics of the participants or the lack of respiratory efficiency. Generally, PEF results see a greater decrease in asthmatic effects on children than PFT results. The results align with other literature.

The severity analysis is subject to bias through the way it’s report. Those within the experimental group may rate severity lower as they expect to see improvement over the 6 weeks. Change could also be caused by external factors such as lifestyle change, time of year or medication compliance. The validity of these results should be questioned but is challenging as the data is not shown in the report.

The study suggests that swimming in a chlorinated pool may cause inflammation of the airways and increase the severity of asthma. This does align with other studies hypothesis however, the evidence in inconclusive. Similar studies conducted in chlorine pools have reported neutrophilic airway inflammation and noncellular inflammation are associated with airway dysfunction in swimmers. This suggests that the combined exposure to chlorine and exercise is presumably unrelated to eosinophilic ‘asthma-like’ inflammation. Further, specific study should be conducted to determine the association between chlorinated pools and asthma within children.

Practical Advice
-       Generally, a swimming program will improve variables associated with children with asthma greater than many other sports

-       Ask participants for direct verbal or non-verbal feedback to limit external factors and conclude if intervention impacted social, cognitive or emotional development

-       Further insight into impacts of chlorinated and non-chlorinate

-        Those with family history of asthma should look to get children into swimming as soon as comfortable

Further Information/Resources
General Information:

American Thoracic Society Guidelines

Exercise Associated with Asthma Control

Specific Information:

Effects of Swimming Training on Aerobic Capacity and Exercise induced Bronchoconstriction in Children with Bronchial Asthma

Effectiveness of Swimming on Lung Function and asthma Control in Children with Asthma

Pros and Cons of Chlorinated Pools and Risk of Asthma