I love running. I became a regular runner - 25 - 28 mi. a week, about 8 months ago. My muscles are still intact, if not even more pronounced from losing some body fat since I started. I have not sustained any injuries or body aches from it and overall I feel that I have benefited a lot.
An important thing to consider is that once you build up good conditioning, your running feels somehow less strenuous and "chronic cardio" is no longer a factor. I just don't feel that cortisol could be continuously released when you feel good.