It is needless to say that running, as well as any other regular endurance exercise, changes the heart. Being a muscular organ, the heart, like all muscles in the body, adapts to the stress of exercise. The question is whether these adaptations are good for the heart or not.
The WHO recommends adults to moderately exercise for 150 minutes or intensely for 75 minutes weekly. They say running can help prevent obesity, high blood pressure, heart conditions, diabetes and stroke, and improve the quality of emotional and mental wellbeing. It also helps to live longer.
Of course, running regularly can not make us immortal, but it is effective at extending life expectancy. Several studies found that a mere 5 to 10 minutes of running a day, reduces the risk of heart disease and premature mortality from all causes.
A routine of regular running is highly effective in prevention of many chronic conditions, cardiovascular diseases, and improvements heart health. However, long-term excess endurance exercise, such as running in marathons, can cause pathologic structural remodeling of the heart and large arteries.
Since human body is not meant for running long distances, excessive running can be dangerous for the heart. Instead of steady state movement, our bodies are made to do physical activity in bursts of exertion followed by recovery. In fact, almost most sports are based on stop-and-go movements, and statistics suggests that physical variation is one of the most important things to consider in running.
Physical variability is also important from the point of view of internal effects on the body. Excessive steady state endurance exercises increase the production of free radicals in the body, reduce immune function, degenerate joints, cause muscle wasting and pro-inflammatory response in the body that can result in heart attack and chronic diseases. Together damage to all the organs in the body, free radicals damage the skin and make us look older.
Running is like a coin which has two sides, and if done improperly, it can have seversequences. If you overdo high intensity exercise, engaging in prolonged sessions daily and over-working your body, you put yourself at risk of lower immunity response and injuries. On the other hand, when we run, the heart beats faster as the activity strengnthens it. With regular running, the resting heart rate gets lower, which extends the heart's life.
So, how much running is good for the heart? Aim at daily exercise, performing different activities to maintain challenge and to dodge overuse injuries. Run several miles a week and aim at 9 minute per mile pace. Introduce running slowly, building up your muscles and speed gradually. Mind signals from your body. If you have any discomfort, back off and search medical evaluation.