What about something preemptive, so people with asthma can do physical activity?
If someone has exercise induced asthma, they should ask their doc for an albuterol metered dose inhaler prescription if the doc agrees. Maybe mastering this breathing technique would make that unnecessary.
Preemptive treatment is the inhaled steroids. Albuteral will treat an attack without steroids. But that will increase heart rate. No medication comes without a side effect.