Effects of physical exercise on lung inflammation in animal models of chronic allergic lung inflammation: a systematic review.

We performed a systematic review to identify and summarize the effects of distinctive aerobic exercise (AE) protocols on chronic allergic lung inflammation reported in asthma animal models. We identified 255 preclinical studies of asthma and AE protocols by comprehensive searches in PubMed, ScienceDirect and LILACS for peer-reviewed journals, using the search components "exercise," "lung inflammation," and "asthma," without restrictions on publication date. Twenty-two studies were selected that met all eligibility criteria. Most studies used an ovalbumin experimental model and performed experiments with BALB/c mice. Most studies performed treadmill AE, using protocols of 30 to 60 minutes, 3 to 5 times/week, for 4 to 8 weeks. The results showed that the effects of AE on lungs were protocol dependent, but generaly, there was a decrease in inflammatory cell influx and Th2 cytokines, as well as an increase in anti-inflammatory defenses. However, the immunoregulation of globulins and nitric oxide levels in asthma seemed to be associated with the onset of AE. The results suggest that AE plays an important immunoregulatory role in animal models of asthma, with effects mainly mediated by increased anti-inflammatory defenses and reduced Th2 response. In parallel, prophylactic and therapeutic AE also played important roles in decreasing bronchial responsiveness and attenuating lung remodeling in animal models of asthma, secondary outcomes in this systematic review. The review protocol was published for free access in October 2017 on the Systematic Review Facility (SyRF) platform (http://syrf.org.uk/protocols/).