I worry sometimes about the actual effects of exercise on our health, and the legitimacy of these studies. It's impossible to detach these studies from the confounding factors - if your health declines (for any reason), you will stop exercising. I feel like we have to take any studies that use correlations with a grain of salt.
How do you study the effects of exercise when there are such massive confounding variables?
How do you study the effects of exercise when there are such massive confounding variables?