Cardiovascular Effects of Endurance Exercise- Good or Bad? Catherine Moltzan MD FRCPC

Potential Benefits of Exercise Training Improvement in coronary artery disease risk factors Improvement in coronary artery disease risk factors Improvement in blood parameters Improvement in blood parameters Improvement in cardiac reserve Improvement in cardiac reserve Reduction in cardiac mortality Reduction in cardiac mortality Improvement in mean life expectancy Improvement in mean life expectancy

How Much is Too Much? Most studies have confirmed that a modest amount of cardio physical activity (45 min to 1 hour per day) is enough to sustain the benefits of exercise training Most studies have confirmed that a modest amount of cardio physical activity (45 min to 1 hour per day) is enough to sustain the benefits of exercise training So…what are the effects/benefits/risks of doing more than this? So…what are the effects/benefits/risks of doing more than this?

Potential Adverse Cardiovascular Events From Endurance Exercies O’Keefe et al. Mayo Clinic Proceedings O’Keefe et al. Mayo Clinic Proceedings Review article with no new data Review article with no new data However, it has gotten quite a bit of press in the mainstream media because of some of the conclusions it draws However, it has gotten quite a bit of press in the mainstream media because of some of the conclusions it draws

Article Highlights 1. Sudden Cardiac Death and Endurance Exercise 1. Sudden Cardiac Death and Endurance Exercise –Rate about 1/ which has not changed despite an increase in the number of marathon participants

Article Highlights- 2 Animal studies Animal studies –Rat study- ultracrazed running rats compared to sedentary rats –Active rats had enlarged hearts, scar tissue/stiffness and an increased susceptibility to heart rhythm problems –However- this is a rat study (not a human one) and humans have the ability to moderate the amount of physical activity that they do

Article Highlights- 3 What is an athlete’s heart and what does it mean? What is an athlete’s heart and what does it mean? –Endurance training leads to increased heart dimensions and increased heart muscle –Changes don’t completely go back to normal even with cessation of endurance training –These changes are often considered to be bad in those with heart disease –What’s the difference- in the athlete’s heart function remains normal

Article Highlights-4 Increase in cardiac enzymes with extreme exercise (50 percent of marathoners) Increase in cardiac enzymes with extreme exercise (50 percent of marathoners) –These enzymes can be associated with heart damage –However, we don’t know the significance of this change in endurance athletes

Article Highlight- 5 Extreme exercise leads to cardiac remodeling on the right side of the heart- usually damage was transient Extreme exercise leads to cardiac remodeling on the right side of the heart- usually damage was transient Case control study suggested that experienced marathoners may even have a the same incidence of heart attacks as a sedentary group Case control study suggested that experienced marathoners may even have a the same incidence of heart attacks as a sedentary group May be mediated by changes in biomarkers during exercise May be mediated by changes in biomarkers during exercise

Article Highlight- 6 Extreme Exercise and Electrical Abnormalities Extreme Exercise and Electrical Abnormalities –Increased risk of heart rhythm abnormalities (atrial fibrillation)- 5X increased risk –Concerning findings- but what is the definition of an “endurance athlete”

Take-Home Message In some individuals extreme exercise may lead to heart problems In some individuals extreme exercise may lead to heart problems For the majority this should not be an issue For the majority this should not be an issue –Train appropriately –Proper attention to hydration and nutrition –Pay attention to other risk factors –“Everything in moderation”