Healthy lungs from a ‘jog in the park’
Physical inactivity is linked to major non-infectious diseases such as asthma and chronic obstructive pulmonary disease (COPD). Yet, there is little hard evidence linking improved respiratory health to regular physical activity. Interestingly, the few high-quality longitudinal studies available suggest that systemic inflammation may play a role, although this link remains untested. Filling this gap in knowledge could make a difference to many with respiratory disease. The EU-funded PAIR project carried out a study to strengthen the evidence of a causal association between physical activity and lung function. Health promoting agencies now have more scientifically concrete evidence upon which to base their advice to the public, encouraging them to increase their physical activity levels. “We hypothesised that associations between physical activity and lung function would be strongest among subjects with high inflammatory burdens (e.g. smokers, asthmatics, those living in high air pollution settings),” explains project PAIR coordinators, Drs Elaine Fuertes and Judith Garcia Aymerich. Data from two large trials PAIR researchers used data from almost 4 000 adults taking part in the European Community Respiratory Health Survey. Results showed that those who did more physical activity that led to sweating or breathlessness had better lung function in the long-term, especially among smokers. Supporting the existence of an inflammation-related biological link, this highlights the importance of physical activity in this higher risk group. The still ongoing Horizon 2020 study ALEC (Ageing lungs in European cohorts) also offers a huge amount of international information. Key to the success of PAIR, the ALEC project is contributing to the evaluation of risk factors of lung function and its decline. Air pollution “Long-term air pollution levels observed in Western Europe don't negate the benefits of physical activity on lung function, which supports the promotion of outdoor activities and active transport,” points out Dr Garcia Aymerich. However, as the benefits of physical activity were slightly reduced in never-smokers living in areas with very high air pollution levels, efforts at controlling air pollution levels are justified. This was a completely novel outcome, as previously, there had been no study that had reported on the combined long-term effects of both physical activity and traffic-related air pollution exposure on lung function. “This is despite the biological plausibility of such associations and the fact that this combination of factors better represents an individual's true exposure,” states Dr Fuertes. Inflammation link The PAIR team looked for a causal role of systemic inflammation between regular physical activity and higher lung function. Using C-reactive protein (CRP), a commonly used biomarker for systemic inflammation, results failed to show that regular long-term physical activity may lower systemic inflammation, and consequently, lead to better lung health. Looking at the future however, Dr Garcia Aymerich supports further investigation into systemic inflammation. “Our study was the first to use a mediation analysis to assess this complete link, but additional studies are needed to confirm our results.” Steps for future research Future studies with detailed and repeated measures of specific types of physical activity should consider other biomarkers of systemic inflammation (e.g. IL6). Another focus should be on additional mechanisms (e.g. changes in body weight and composition or lung mechanics) that are also likely to play an important mediating role. Work continues after the close of the project. Currently, PAIR results are being incorporated into an online COPD risk prediction tool, an important part of the end-product of the ALEC collaboration that will be ready for release in 2019. Dr Fuertes concludes, “The results from PAIR, combined with other efforts, will be used to improve decision making and promote behavioural change in relation to respiratory health.”
Keywords
PAIR, physical activity, lung function, biomarker, CRP
