Encourage exercise in patients with asthma
Patients with asthma often participate less in physical activity because they are afraid of triggering symptoms. However, there is evidence that exercise has important clinical benefits in patients with conditions such as cystic fibrosis and COPD.
The authors of this paper sought to examine the effects of physical exercise on asthma patients by monitoring bronchial hyperresponsiveness (BHR). What effect do differing levels of exercise have on this important determinant of asthma severity?
The European Community Respiratory Health Survey II recruited 7,648 participants of whom 5,158 completed the study. The study involved completion of questionnaires about the frequency and nature of the participants' physical activity and collection of data about height, weight, age, sex, smoking, asthma status and other illnesses.
Participants underwent tests for BHR, using methacholine provocation and spirometry. BHR was defined in terms of a decrease in FEV1 of at least 20% of its post-saline value after a maximum dose of 2mg methacholine.
The study found a clear statistically significant negative correlation between both the frequency and duration of physical activity and BHR. This ranged from a prevalence of BHR of 14.5% in low exercisers to 11.6% in high exercisers. Statistical tools were used to validate the results and account for confounding factors and the authors report there was no association with any of the other variables.
However, the changes indicated in BHR were attributable to self-reported levels of physical exercise and it is unclear how certain the researchers could be that the other variables had been correctly accounted for.
The authors comment that the causal link between BHR and exercise is not clear, but one possible mechanism to explain the association is that exercise acts as an anti-inflammatory on the airways.
From a primary care perspective this is yet another paper promoting the benefits of physical exercise for our patients and reinforces a message we should be banging home with every consultation.
Shaaban R, Leynaert B, Soussan D et al. Physical activity and bronchial hyperresponsiveness: European Community Respiratory Health Survey II. Thorax 2007;62:403–10author Reviewer
Dr Peter Saul
GP, Wrexham and hospital practitioner in paediatrics (asthma and allergy)