This press release in advance of a poster presentation is doing the rounds on social media at the moment:
Ability to lift weights quickly can mean a longer life
A factual association is probably true between being above the median in ability to do work on a specifically selected gym machine and longevity.
What does this mean? It's observational. Hypothesis generation only.
Perhaps non-athletes with higher power output might live longer because they have excellent mitochondria and our mitochondria are essentially what determine our longevity. Having good mitochondria might well mean that you exercise spontaneously without describing yourself as an athlete. As in I might carry a couple of sacks of chicken food myself rather than wait for Paul the yard-man and his barrow. But this is an effect, not a cause.
Non-athletes with low power output may be the converse. They have mitochondria in which the cardiolipins anchoring their cytochrome-C to the mitochondrial inner membrane are as flimsy as a PUFA in a deep fat fryer, which are willing to trigger apoptosis at the drop of a superoxide molecule. Poor mitochondria, less muscle fibres giving sarcopaenia, shorter longevity. Probably already giving diabetes in-situ. An AHA poster-child.
Taking someone from the second category and making them exercise might convert them to being healthy with a long life span. Maybe.
Or, there again, it might make the gym sessions so unbearable that they quit.
Or, if you don't let them quit, it might simply make no difference.
Or, if you don't let them quit, it might kill them sooner!
As Eeyore said "think of all the possibilities, Piglet, before you settle down to enjoy yourselves".
The study (as per press release) tests nothing. Researchers are giving very specific advice based on an untested observation which might be going to make them look very, very stupid when the results of an intervention to test their hypothesis actually refutes it. But that will take decades and hopefully the researches will be retired by then. More likely it will be ignored or termed a paradox. All the possibilities Piglet.......
EDIT or the intervention might show benefit. That's not impossible! END EDIT
Declaration: I have nothing against exercise. Nowadays I mostly boulder because it is three dimensional problem solving using muscle groups to failure on a regular basis. Plus I also try to keep my cardiolipins as saturated as practical!