Effects of physical therapy on lung function in children with asthma: a systematic review and meta-analysis
Zhang W, Qiu W, Liu L, Yang W, Liu H. Effects of physical therapy on lung function in children with asthma: a systematic review and meta-analysis. Pediatric Research. 89(6):1343-1351. doi:10.1038/s41390-020-0874-xLink to Original Article: https://www.nature.com/articles/s41390-020-0874-x
Key Points
1. The study aimed to investigate the effects of physical therapy on lung function in children with asthma, including physical training, breathing exercise, and inspiratory muscle training (IMT).
2. The systematic review included 18 studies involving 711 participants, with 16 studies involving physical training, 1 study involving breathing exercise, and 1 study involving breathing exercise plus IMT. The studies were conducted between 1990 and 2018 in 12 countries, primarily in Europe and America.
3. Meta-analysis of the studies showed a significant improvement in forced vital capacity (FVC(%pred)) in groups receiving physical training compared to control groups, but no significant differences were found in forced expiratory volume in the first second (FEV1(%pred)) or peak expiratory flow (PEF(%pred).
4. The study found high risk of performance bias due to the inability to blind participants in physical training interventions. Clinical and methodological diversity in the interventions were also noted as potential sources of heterogeneity.
5. The quality of evidence based on the GRADE system was assessed as moderate, with a need for further research on the mode, duration, and frequency of physical training interventions in asthmatic children.
6. The study concludes that physical training significantly improved FVC(%pred) in children with asthma, supporting the therapy of physical training in this population, while highlighting the need for more research on the effects of breathing exercise and IMT in children with asthma.
Introduction
The introductory section of the research paper discusses the widespread impact of asthma on both the healthcare system and the global population, with an estimated 300 million affected individuals. It highlights the uncertainties surrounding the condition's etiology, pointing to environmental and genetic risk factors. The symptoms of asthma, including wheezing, coughing, shortness of breath, and chest tightness as a result of airway hyperresponsiveness and airway remodeling, are outlined, with acute exacerbations posing a significant threat to patients' well-being and requiring immediate medical attention. The comprehensive nature of asthma care, which includes pharmacologic therapy and physical therapy, is emphasized. Three types of physical therapy techniques are used to treat individuals with asthmatic conditions. These techniques include physical training, breathing exercises, and inspiratory muscle training (IMT), all of which aim to improve lung function. Physical training is focused on strengthening the muscles used for breathing in and out, reducing inflammation in the airways, and increasing the openness of bronchioles. Breathing exercises, such as the Papworth method and the Buteko breathing techniques, concentrate on developing a pattern of long exhalation and a reduced respiratory rate to alleviate hyperventilation and hyperinflation. Lastly, IMT places an emphasis on strengthening the diaphragm and the accessory muscles used for breathing in order to enhance their endurance and power. The authors note that while previous reviews have evaluated the effects of physical therapy on asthma patients, they have not exclusively focused on children or considered all three relevant physical therapies. As a result, the paper's systematic review and meta-analysis aim to specifically examine the effects of physical therapy on lung function in children with asthma, providing evidence-based information for doctors to make informed decisions regarding the choice of physical therapy for asthmatic children.
Search strategy
PubMed, Embase, and the Cochrane Library were searched on November 30, 2018 to find research articles relevant to the studies. In addition, the reference lists of studies and relevant systematic reviews were scanned for further information.
Table 1
Search strategy in PubMed
Selection criteria
The research paper applied specific criteria for the selection of relevant studies. The inclusion criteria encompassed randomized controlled trials (RCTs) published in English that involved participants under 18 years of age with a diagnosis of asthma based on clearly defined or internationally recognized criteria. Additionally, the experimental group had to receive at least one of the three main physical therapies (physical training, breathing exercises, and/or IMT) alongside the standard treatment for a minimum of 2 weeks, and the study had to report on various lung function parameters at the end of the intervention period. These parameters included peak expiratory flow (PEF), forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), FEV1/FVC ratio, and forced expiratory flow (FEF) in percent predicted values or absolute values.
Exclusion criteria involved studies that did not meet the specified inclusion criteria. The study selection process was carried out independently by two authors, who initially assessed the titles and abstracts of the identified papers, with those meeting the criteria being subjected to a full-text assessment. Any disagreements between the two authors were resolved through consultation with a third author. This rigorous selection process aimed to ensure that only the most relevant studies were included for analysis, enhancing the overall reliability and validity of the research findings.
Data extraction
Two authors conducted separate searches for relevant research studies. Once the extraction process was completed, the data were cross-checked by the two authors with each other. In case of any disagreements or disputes, a third author was involved to resolve them.
Risk of bias assessment
The methodological quality of the included studies in the research paper was assessed using the Cochrane Collaboration's tool by two independent authors. The assessment included the evaluation of random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data, selective reporting, and other biases. Each domain was categorized as having a high, low, or unclear level of bias. In cases of disagreement, resolution was reached through discussion or with the assistance of a third author. This process ensures that the studies' methodological quality was rigorously evaluated to provide a comprehensive understanding of the potential biases and limitations in the included research.
Statistical analysis
The statistical analysis section of the research paper focused on comparing the effects of physical therapy on lung function in children with asthma. The experimental group received physical therapy in addition to the standard control group treatments, and studies with significant baseline differences between groups were excluded. The analysis utilized the Revman Manager 5.3 to calculate mean differences and 95% confidence intervals using a random-effects model due to the diverse interventions. A statistically significant difference was defined as P < 0.05.
The meta-analysis included studies reporting outcomes such as peak expiratory flow in percent predicted values (PEF(%pred)), forced expiratory volume in the first second in percent predicted values (FEV1(%pred)), or forced vital capacity in percent predicted values (FVC(%pred)). Data from studies reporting pre and post-intervention mean and standard deviation were used to calculate post-intervention values. If necessary, standard error of the mean or 95% CI values were converted into standard deviations.
Subgroup analyses were not conducted for studies with breathing exercises or inspiratory muscle training (IMT) due to inclusion criteria not being met. Heterogeneity was assessed using χ 2 and I ² tests, with statistical significance set at P < 0.10 and moderate-to-high heterogeneity at I ² > 50%. Sensitivity analysis was performed by sequentially excluding one study at a time and comparing the results using both random and fixed-effect models. Publication bias was assessed using a funnel plot and Egger's tests in Stata 14.0.
Lastly, the quality of evidence was assessed using the grading of recommendations assessment, development, and evaluation (GRADE) system to ensure the reliability and validity of the findings.
Results
The study identified 6463 records through database searches and 11 additional records through reference list scanning, resulting in a total of 6474 records. After removing duplicates, 4656 records remained, and 4571 were excluded based on title and/or abstract screening. The full texts of the remaining 85 articles were assessed, and 67 were excluded due to various reasons, leaving 18 articles that met the inclusion criteria. Of these, 11 articles reporting PEF(%pred), FEV1(%pred), or FVC(%pred) were included for meta-analysis. After the rigorous selection process, 11 articles were selected for meta-analysis to evaluate the effects of physical therapy, including physical training, breathing exercises, and inspiratory muscle training, on lung function in children with asthma, providing valuable evidence for healthcare professionals in choosing appropriate physical therapy interventions for asthmatic children.
Study characteristics of the included studies
The research paper included a total of 18 studies with 711 participants. Sixteen studies focused on physical training involving 631 participants, one study involved 30 participants in breathing exercises, and one study involved 50 participants in breathing exercises plus inspiratory muscle training (IMT). The studies were published between 1990 and 2018, with 15 studies conducted between 2000 and 2018. They were conducted in 12 countries, primarily in Europe and America. The age range (mean) of participants overall was 7-18 years, with a mean age of 11.71 years. For studies involving breathing exercise or IMT, the age range was 8-17 years with a mean age of 12.59 years, and for studies involving physical training, the age range was 7-18 years with a mean age of 10.83 years.
Risk of bias in the included studies
Allocation
All the included studies were randomly allocated, but only five studies were deemed to have described a well-randomized method and were judged as low risk. Two studies reported a non-random component in the sequence generation process and were judged as high risk. Only one study provided details regarding allocation concealment and was judged as low risk, while the remainder were classified as unclear risk.
Blinding
All the studies were judged as high risk due to the impossibility of avoiding performance bias in physical therapy. One study specified blinding of outcome assessment and was judged as low risk, while the others were judged as an unclear risk of detection bias.
Incomplete outcome data
Six studies had a high rate of withdrawal and were considered high risk. Two studies specified the reason for withdrawal but were considered low risk because the missing outcome data were unrelated to the true outcome. The remaining ten studies were considered low risk.
Selective reporting
The study protocols were not available, but outcomes were listed in the Methods section of the studies. Therefore, all studies were considered low risk
Other potential source of bias
Three out of the 18 studies reported a significant difference at baseline between the experimental and control groups.
Types of physical therapy
The research paper summarized the different types of physical therapy interventions used in studies to investigate their effects on lung function in children with asthma. The interventions included breathing exercises, inspiratory muscle training (IMT), and physical training involving various activities such as walking, running, swimming, cycling, basketball, and Tai Chi. The duration of the interventions ranged from 5 weeks to 1 year, with most studies having 2-3 sessions per week lasting 40-60 minutes per session.
Outcome measures and findings
In all 18 studies, the experimental groups were compared to the control group who received no physical therapy. The outcomes of the interventions were assessed in terms of lung function measures, including forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and peak expiratory flow (PEF), reported as percent predicted values or absolute values. Meta-analyses were conducted for the outcomes where applicable. The results showed a significant improvement in FEV1 and FVC, as reported by a number of studies, while the meta-analyses indicated a statistically significant difference in post-intervention FVC (%pred) but not for FEV1 and PEF. The studies demonstrated acceptable or no heterogeneity for these outcomes.
In summary, the research paper highlighted the various types of physical therapy interventions and their effects on lung function in children with asthma. It provided evidence for the potential benefits of physical therapy interventions in improving lung function, particularly in relation to FEV1 and FVC, which are important indicators of asthma control.
Discussion
The study aimed to investigate the effects of physical therapy on lung function in children with asthma. It included 18 studies, 16 related to physical training and 2 to breathing exercise or inspiratory muscle training (IMT). The meta-analysis included 11 physical training studies, which showed a significant improvement in FVC(%pred) compared to control groups, but no significant difference in FEV1(%pred) or PEF(%pred). The study highlighted the inclusion of the most relevant physical therapies for asthma and the use of commonly used parameters to evaluate lung function. The significant improvement in FVC(%pred) from physical training suggests its encouragement for children with asthma. However, the study noted the complexities of asthma pathophysiology, indicating that while physical training improved pulmonary capacity, its effects on airway obstruction and inflammation were not obvious, explaining the lack of significant improvement in FEV1(%pred) and PEF(%pred). More research on breathing exercise and IMT is needed. The study also identified methodological and clinical diversity in physical training interventions, emphasizing the need for research on the mode, duration, and frequency of physical training. The study emphasized the importance of considering the effects of physical training on psychosocial health in addition to physical health. Overall, the study provides insight into the effects of physical training on lung function in children with asthma while identifying areas for further research.
Limitiations
The authors of the research paper acknowledge several limitations in their study. First, they note that all the included studies have a high risk of performance bias because it was not feasible to blind the participants who were involved in physical training. This suggests that there might be a potential for performance-related influences on the outcomes. Second, the authors highlight the presence of clinical heterogeneity resulting from the diversity of the intervention designs used in the included studies. This variance in intervention approaches could affect the overall findings and generalizability of the results. Third, the authors point out that the outcome measures used in their meta-analysis are limited, indicating a need for broader outcome measures that could better reflect the respiratory condition of the patients. Specifically, they suggest that incorporating measures such as respiratory muscle strength and dyspnea could provide a more comprehensive assessment of the impact of physical therapy on lung function in children with asthma. In summary, the study's limitations include the high risk of performance bias, clinical heterogeneity due to diverse intervention designs, and a narrow range of outcome measures, indicating potential areas for further research and improvement in understanding the effects of physical therapy on lung function in pediatric asthma.
Conclusion
The systematic review and meta-analysis found a significant improvement in FVC(%pred) in children with asthma who received physical training. The current research supports the use of physical training for children with asthma. However, further research is needed to determine the ideal mode, duration, and frequency of physical training. Additionally, more trials examining the effects of breathing exercises and IMT in children with asthma are also needed.
Opportunities for Future Research
1. Conduct a comparative analysis of the effects of breathing exercises, inspiratory muscle training (IMT), and physical training on lung function in children with asthma to determine the relative efficacy of each intervention.
2. Investigate the long-term effects of different modes, durations, and frequencies of physical training on lung function in children with asthma, considering the clinical and methodological diversity observed in previous studies.
3. Conduct randomized controlled trials (RCTs) to assess the effects of breathing exercise and IMT on lung function in children with asthma, considering the limited number of studies involving these interventions in the current meta-analysis.
4. Explore additional outcome measures that reflect respiratory condition more comprehensively, such as respiratory muscle strength and dyspnea, to gain a more comprehensive understanding of the impact of physical therapy on children with asthma.
5. Investigate the potential psychosocial health benefits of physical training in children with asthma to assess its holistic impact beyond physical health.
6. Examine the influence of different variables such as region, race, age, and sex on the efficacy of physical therapy interventions for children with asthma to better understand the personalized approach to managing asthma through physical interventions.
