“The best prescription for light jogging was a slow and steady pace at about 5 mph, exercising 2-3 times per week, for 1 - 2 1/2 hours per week, which is healthier than jogging much harder. Intense, fast running can shorten your life to the same mortality as a sedentary non-jogger.
“Exercise does wonders for us in terms of blood pressure, cholesterol and weight. However, when you perform exercise to extreme levels, the theory is that you are potentially causing structural or ultra-structural damage to the heart. You are causing possible side effects which change the loading conditions on the heart, so the function may be reduced. There is increased blood volume to the heart, less efficient pumping of blood, thickening of cardiac tissue, arrhythmia, and damage to the arteries which may form earlier calcification or stiffening. "Slow and Steady," Dr. Tara Narula, Cardiologist at Lenox Hill Hospital in New York, CBS This Morning, February 3, 2015