Lest you think all of this endurance sporting is good for you, consider this report published in the European Heart Journal. They say that some super-fit athletes who train too hard can develop ventricular arrhythmia, a condition where the heart beats irregularly. It looks like this is more for triathletes and less for jogglers.
You shouldn’t worry about it too much however, the condition is pretty rare. But if there are heart conditions in your family history, you might want to have a check-up before participating in that next marathon or even joggling an ultramarathon. There are so few jogglers in the joggling community that we really can’t afford to lose any!