While exercise can trigger asthma symptoms in some people, there is also evidence that physically active asthmatics tend to have better overall asthma control than their sedentary counterparts. But whether that signals a benefit of exercise, per se, has been unclear. To study this, researchers from Canada recruited 36 sedentary adults with asthma symptoms that were only partially controlled. Nearly all were on medication, including, in many cases, drugs taken regularly to prevent asthma attacks.

The researchers had 18 study participants go through three months of supervised exercise training, where they worked out aerobically three times per week – with activities like jogging, walking on a treadmill or pedaling on a stationary bike – and performed strengthening exercises once a week.The exercisers then continued to work out on their own for another three months. The rest of the study participants served as a control group, maintaining their usual lifestyle habits.