I can no longer run without sacrificing my knees. Hopefully swimming will work just as effectively for this premise. I took the months of December and January off from swimming because the water is too cold, but swimming, biking, walking and dancing are in my exercise plans for the coming months.

Perhaps. But is it also not likely, that women who run three times a week, also have healthier diets, use fewer drugs and expose themselves to better environments generally. It may be true, but is it directly or indirectly true ?