Excessive endurance training might be harmful to the heart
A recent literature review research study by O’Keefe (O’Keefe JH, Patil HR, Lavie C, et al. Potential adverse cardiovascular effects from excessive endurance exercise. Mayo Clin Proc. June 2012:87(6)) suggests that chronic training for longer endurance events such as marathons, ultra-endurance running events, ironman distance triathlons and long distance bicycle races may cause structural damage to the heart and large arteries.
O’Keefe did not want the report to take away the importance of regular exercise. “Physically active people are much healthier than their sedentary counterparts. Exercise is one of the most important things you need to do on a daily basis. But what this paper points out is that a lot of people do not understand that the lion’s share of health benefits accrue at a relatively modest level.”
At what point is exercise too much? There is a fine line between healthy exercise and harmful behavior/habits. We know that excessive exercise can result in other injuries, such as stress fractures, joint degeneration, hormonal irregularities, and bone demineralization to name a few.
Events are a great way to motivate and hold accountable your training efforts. Bigger events (such as distance and intensity) come at a price; physically, mentally, monetarily and sociologically. Balancing your long term health should be an important consideration in the selection of training/racing events.