Which comes first: Exercise-induced asthma or obesity?

The findings are important, since 2.3 million Canadians are affected by asthma according to Statistics Canada.

ETA affects up to 90 percent of asthma sufferers, says lead author Simon Bacon, a professor at the Concordia Department of Exercise Science and a researcher at the Hôpital du Sacré-Coeur de Montréal. "Compared with normal-weight participants, patients who were overweight or obese were more likely to report ETA. To our knowledge, there are no studies that have explored this relationship," he says. "We also found that for every one-point increase in body mass index score was associated with a 9 percent increase in the probability of reporting exercise-induced asthma."

Participants who took part in the investigation suffered from intermittent as well as mild, moderate and severe persistent asthma. Their body mass index was calculated according to their reported height and weight. Patients were also asked to indicate factors -- exercise, animals, dust, pollen, aspirin, stress, emotions or cold air -- that could trigger their asthma.

"Exercise-induced asthma may lead to a sedentary lifestyle, increased weight and can fuel a downward spiral to worsened health," says Dr. Bacon. "Given the importance of exercise and regular physical activity in weight management, greater care should be taken when working with asthma patients to refer them to appropriate weight management specialists to help them control and safely reduce their weight."

The study was funded by the Social Sciences and Humanities Research Council, the Canadian Institute of Health Research and the Fonds de la Recherche en Santé du Québec.

The article was coauthored by Simon L. Bacon, Amanda Rizk and Alicia Wright of Concordia University and the Hôpital du Sacré-Coeur de Montréal; Kim L. Lavoie and Ariane Jacob of the Université du Québec à Montréal and the Hôpital du Sacre-Coeur de Montréal.