The interesting part of this for me is their conclusion that that there is no such thing as being too fit in terms of longevity and health. This is surprising

The interesting part of this for me is their conclusion that that there is no such thing as being too fit in terms of longevity and health. This is surprising because a lot of athletic and fitness endeavours I've seen stress the importance of getting adequate rest days and not overworking. For example, in weight lifting circles, people often stress that lifting every day can lead to injuries and negative health effects. I wonder if this article calls that into question or perhaps they are just overlooking that the most "highly fit" people also take adequate rest days as a part of their routine. It's probably also likely that the more highly fit someone is, the more likely they are to have other factors that increase longevity - ie. it means they have the leisure time to exercise and maintain a high level of fitness, it means they likely watch what they eat etc. I wonder how much of this is direct causation vs correlation.