Exercise intensity modifies acute inflammatory response in adults with asthma
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Among physically inactive adults with asthma, exercise intensity modified the acute inflammatory response to exercise, researchers reported in Annals of the American Thoracic Society.
“This is the first study internationally to examine the impact of exercise intensity on inflammation in adults with asthma,” Hayley A. Scott, PhD, research dietitian at the Priority Research Centre for Healthy Lungs at the University of Newcastle in Australia, and colleagues wrote. “We found that, while moderate exercise was associated with a reduction in sputum eosinophils, vigorous exercise had no effect.”
The randomized controlled trial included 56 participants (mean age, 33.4 years; 75% women) with asthma who were considered physically inactive. All participants were randomly assigned to undergo no intervention (n = 18), perform 45 minutes of moderate exercise (n = 19) or perform 30 minutes of vigorous exercise (n = 19). Researchers collected induced sputum and blood samples from each participant at baseline and 4 hours after intervention.
Participants in the moderate exercise group experienced a reduction in sputum eosinophil count (–173 x 104/mL; P = .032) and sputum percent eosinophils (–2.2%; P = .049) 4 hours after exercise. Participants in the vigorous exercise group experienced no effect on airway inflammation.
The anti-inflammatory effects of moderate exercise were greatest among participants with eosinophilic asthma, with larger reductions in sputum eosinophils and larger increases in plasma interleukin-1 (IL-1) receptor antagonist compared with participants without eosinophilic asthma (P = .01). Vigorous exercise led to a pro-inflammatory response among participants with eosinophilic asthma, which was indicated by serum IL-5 and IL-1-beta increases. This had no effect on airway inflammation, according to the researchers.
“Our study suggests that the beneficial effects of exercise in asthma may be driven, at least in part, by reductions in airway inflammation, as we found a single bout of moderate exercise is associated with a short-term reduction in sputum eosinophilia. Interestingly, the inflammatory effects differed according to the intensity of exercise performed: while moderate exercise exerted anti-inflammatory effects by driving reductions in eosinophilic airway inflammation, vigorous exercise had no effect on airway inflammation,” the researchers wrote. “We also observed a significant interaction between exercise intensity and asthma phenotype, whereby moderate exercise reduced eosinophilic airway inflammation in participants with eosinophilic asthma but not in participants with non-eosinophilic asthma.”
According to the researchers, this study was limited by its sample size and underpowered to compare moderate and vigorous exercise.
“Future studies should investigate the impact of exercise training at different intensities on inflammation and clinical asthma outcomes,” the researchers wrote.