Earlier quoted context omitted.
Yeah, "couch potatoes" in Copenhagen likely rank in the 90th percentile in terms of overall physical activity for most American cities. What this study says is, "Running really fast (> 7mph for four hours a week is not exactly a cakewalk) for long periods of time might reduce your mortality.
> might reduce your mortality might increase your mortality, actually. That is reduce your life expectancy .
Argh, you're right, reduce your life expectancy.