Right. There are different types of asthma. While some types may be reduced or eliminated by something like running, other types of asthma may be worsened, and running could end up killing the asthmatic. It's possible the effects of "allergic asthma" could be reduced by exercise.
It seems to me like "asthma" is more of a catch-all term used to describe multiple diseases/disorders that happen to present themselves in a similar manner.
I, too, have asthma. Mine is triggered by:
- excessive physical activity (moderate exercise usually isn't a problem)
- allergies (e.g.: cat hair)
- very strong smells
- most perfumes
- cigarette smoke
- gusts of cold air
- hot, humid air
- high levels of stress
Despite all of these triggers, I have things pretty much under control with daily medications (allergy and asthma), a "rescue" inhaler as needed, and special breathing techniques. I played youth soccer and I was a trumpet and french horn player in my high school's marching and concert bands, although these activities became more difficult the older I got.
My asthma is hereditary, though, so this study really wouldn't apply to me. (I've had asthma since birth.)