Sore after every workout

[Obs]

I was an exercise physiologists before I do what I'm doing now. If your getting sore after every workout. That's a great indicator of over training syndrome. After a few weeks of consistent exercise soreness should be very mild if any af all. As some mentioned, one reason could be the number of miles you were putting on, another reason could be not getting enough nutrients or both.

Running in and of itself is not bad for the heart. However there is growing amounts of scientific data that extreme endurance events maybe just as bad on the heart as being sedintary. The basic theory is that because you're exercising so much, the heart and arterial tissues are exposed to highly reactive oxygen species as a product of oxidative metabolism. This is being called Chronic oxydative Stress. I haven't really looked at that literature in a number of years since that's not my field. But it might be worth a pubmed or google search to familiarize yourself with the theory.

Rhabdomyolysis: Symptoms, Causes, and Treatments
Keeping muscles in a prolonged broken down state is bad in general. Dehydration does not help either.
Kidneys take a hard hit in overtraining.