I'm trying to make clear that I don't think the study necessarily reaches poor conclusions (I've had a chance to read it now), but it's not exactly new and exciting--"exercise is good for you." It does, however, raise a lot of questions. (Hey, taking scientific studies apart is part of my job description.)

Also, this is from the paper regarding their break points:
In the absence of clear evidence defining the amount of exercise necessary to combat the negative effects of inactivity, we pragmatically set standards for acceptance into the study. For men this was the ability to cycle 100 km in 6.5 h while for women the standard was set at the ability to regularly cycle 60 km in 5.5 h. The difference between sexes was necessary because of the paucity of women cyclists aged >55 years who regularly cycle 100 km.