Exercise as it relates to Disease/A burden on physical activity – How extrapulmonary effects cause negative implications on patients with COPD

What is the background to this research?
Chronic Obstructive Pulmonary Disease (COPD) describes a variety of chronic diseases causing breathing difficulties of the lung. COPD-induced breathing difficulties are likely to arise from diseases causing airflow limitations through the narrowing or partial blockages leading to the lungs. These may include but are not restrained to; Asthma, Emphysema, and Chronic Bronchitis. The disease may be genetically inherited or developed via an unhealthy lifestyle. Not only correlated with respiratory impairments, people suffering from COPD are strongly linked to extrapulmonary diseases, a broad term used to describe diseases not directly affiliated with the lungs. The primary purpose of this study was to identify how these diseases can cause reductions in physical activity amongst patients diagnosed with COPD.

Whilst there is no cure for COPD, treatment is available to moderate the development of the disease. Positive correlations between low-intensity physical activity of a high volume and COPD are apparent, potentially due to the reductions in systemic inflammation that may occur as a result of the exercise. Within the study, physical activity status was not previously measured, hence making previous physical status an unknown contributor to the results.

Where is the research from?
The leading author of the study, Henrik Watz, is employed by the Pulmonary Research Institute and has largely been involved with research encompassing pulmonary and systemic areas. This particular research article was based at the ‘Pulmonary Research Institute’ at Hospital Grosshansdorf (Schleswig-Holstein, Germany), – between February and November 2006, and published by the American Journal of Respiratory and Critical Care Medicine. The findings developed in the article are likely to be accurate at the time of publication due to the researcher's experience and journal publication, however, may have a potential level of bias as diseases outside of the lung were not sufficiently taken into consideration when determining the causes for physical inactivity.

What kind of research was this?
The study was conducted in the form of an observational study, more specifically as a cross-sectional study. A cross-sectional study is cost-effective and has the ability to draw conclusions of a particular topic based upon a specific population sample, hereby being ideal when determining aspects such as risk factors or contributing elements. Since only a certain amount of participants take part in a cross-sectional study, the results may not be truly reflective on the whole target population and hence will not reflect the major severity of the issue associated with any outliers found in the study. Furthermore, a cross-sectional study tends to group various findings together to determine an overall outcome of a study. Where some participants may experience reductions in physical activity from certain factors (i.e. asthma), it is not confirmed that these will have the same impact on other participants, hence adding further bias to the study findings. A longitudinal study may have been a more appropriate approach when analysing the results, as the findings may have a lowered chance of bias due to the study duration and consistency of results. With this increased duration, potential trends in the data can be viewed and ultimately suggest reasoning for physical inactivity.

What did the research involve?
Patients with clinically stable levels of COPD expressing interest in the study were collected from the Institute's database and categorised into areas of concern relating to their COPD. The study consisted of 170 patients (male n=128, female n=42; mean age=62yrs). Assessments were undertaken to determine whether additional diseases had a major impact on the amount of physical activity performed by each participant. Participants were graded against the GOLD (Global Initiative for Chronic Obstructive Lung Disease - stages I-IV) and BODE (body mass index, airway obstruction, Dyspnea, and exercise capacity) scoring systems. Both GOLD and BODE scoring systems grade the severity of COPD symptoms possessed by an individual, with a higher score reflecting more severe outcomes (GOLD: 1-4; BODE: 1-10). Participants were assessed over 5-6 days using discrete equipment on various components including the quantity of physical activity (accelerometer), muscular status (grip strength test) and cardiovascular status (various; including echocardiography). Alcohol consumption, current smoking and educational status were also evaluated. Based upon the physical status of the patients involved, a cross-sectional study approach was suitable for this research, however, the results may not reflect accurate long-term outcomes. The methodology is susceptible to reliability errors as there is likely to be a strong chance of bias regarding the selection of participants - through which only those patients who were willing to participate in clinical procedures were selected.

Limitations to the study can be noted as no control group was included in the study, therefore making collected data difficult to interpret in terms of severity amongst various COPD populations. There is a strong chance for potential unnatural collected data as participants may have altered lifestyle engagements to decrease the severity of their individual results. The positioning of the accelerometer may provide inaccurate readings depending on the type of physical activity performed, as not all movements are likely to be registered by the device.

What were the basic results?
The article hypothesised that physical inactivity could be explained due to the co-morbidities of COPD and their related consequences on physical status. The results had matched the presented hypothesis; however, it was discovered that there was a limited correlation between airway obstruction and reduced levels of physical activity. Socioeconomic status, history of chronic diseases and lifestyle were all directly related to reductions in physical activity. This suggests that additional diseases are likely to have greater influences on physical status, in comparison to COPD-induced pulmonary issues. COPD may not be the primary contributor to physical inactivity, rather is likely to worsen other chronic diseases until ultimately reaching a stage in which physical activity participation is restricted. Furthermore, because of these restrictions, a COPD patient is less likely to have a positive attitude towards engaging in a healthier lifestyle, adding to the limitations prompted by the disease.

The basic findings presented in the article are similar to those expressed amongst other studies. An increased sedentary lifestyle is strongly linked to the development of further chronic diseases. Regardless of physical status, breaking up prolonged sedentary durations is strongly linked to a decreased mortality rate amongst the whole population, and may further benefit the rehabilitation to a healthier lifestyle.

What conclusions can we take from this research?
The study concluded that reductions in physical activity amongst COPD patients are not only a result of the COPD-induced pulmonary effects, rather also are associated with additional diseases outside of the lung. In accordance with the article's findings, physical inactivity prevalence demonstrated strong associations across all participants, identifying the influence of COPD on additional chronic diseases. Despite associations between additional diseases and COPD being present across each participant, further research is required to determine whether these additional diseases are causative for physical inactivity within each individual.

Watz has since released additional articles relating to COPD in which more detailed findings were presented using similar methods - indicating the validity of the results. Alterations to the methodology may be necessary to further quantify these findings.

Practical advice
Initiating a healthy lifestyle may be difficult due to the potential negative attitude and previous experience of physical activity possessed by a COPD patient. COPD patients should take caution when engaging in physical activity as there may be an increased risk of injury resulting from diseases external to the lungs. Reductions in systemic inflammation are likely to benefit the individual as the heart will become more efficient in delivering oxygenated blood around the body. Aerobic exercise is found to be most beneficial in reducing the risks of extrapulmonary diseases leading to a COPD-induced hospitalisation. Strength training has been shown to benefit patients with stable COPD by encouraging increased blood flow and muscular regeneration previously affected by prolonged durations of physical inactivity, however, should be cautiously proceeded via professional assistance to help prevent the risk of injuries from occurring.

Useful Resources
Background information on COPD:

https://lungfoundation.com.au/patient-support/copd/

https://www.nhlbi.nih.gov/health-topics/copd

GOLD Stages:

https://lunginstitute.com/blog/gold-copd-stages/

 BODE index and Further reading: 

https://www.nejm.org/doi/pdf/10.1056/NEJMoa021322