There are other more trustworthy sources of information you could look into, like American College of Sports Medicine, American Council on Exercise, etc, and they could potentially have some resources for your questions.

But they'll probably just try to sell you a book... it's funny, I, in a way, consider fitness to be a form of health, and a gym to be a form of healthcare in a way, and unfortunately like other healthcare options, like doctor's, pharmacies, etc. The realm of fitness is a no man's land. You can do or get away with anything.