Maybe a lot of those cases are what would now be described as exercise induced asthma. I wonder how many of those folks still kept engaging in vigorous activities as they aged?
My brother is 38, he had childhood asthma, it never slowed him down. Inhalers, allergy shots the whole nine yards. He played sports through college, and still runs. The allergist said even though back then it wasn't recommended, the fact that he was so active, in spite of the asthma, helped him in the long run.