​Extreme endurance exercise, are you doing more harm than good?

Post by Emily White
 
We are constantly told that some form of exercise is crucial for the prevention of a wide range of disease and will benefit cardiovascular health considerably. But how much is too much? Many studies are now in fact suggesting that long term; excessive endurance physical activity could in fact be doing more harm than good.

In particular cardiologist James O’Keefe suggests that exercise that is performed beyond a certain threshold can actually contribute to heart disease and undo the benefits that are associated with moderate exercise. According to O’Keefe, extreme exercise has been found to be associated with arterial fibrillation that can increase your chance of a stroke (1).  In particular it is chronic training and competing in events such as marathons, ironman distance triathlons and long distance cycling that can induce this pathologic structural remodeling of the heart (2). In addition long term, excessive exercise may be associated with coronary artery calcification and diastolic dysfunction.
 
A recent study looked at sedentary individuals, and found that even small bouts of exercise (up to 15 minutes per day) saw substantial benefits to health and these were continually seen with up to one hour of exercise per day. It was however found that the mortality benefits of exercise peak at about 60 minutes of vigorous exercise per day (2).
 
Another study found that plasma levels of cardiac troponin (cTn) were elevated after bouts of prolonged exercise in supposedly healthy individuals. cTn is a biomarker consistent with myocardial cell damage (3, 4).
 
So if you want to keep fit and healthy, what is the best thing to do?

• Resistance training is the most effective form of exercise for overall health and weight loss over the long term (5).Resistance training can increase your metabolic rate and result in greater muscle retention (6) which is extremely important, especially as you get older! Performing at least 2 strength sessions per week can be amazing for your health.
• High intensity interval training (HIIT) can also be very beneficial to your health. It can promote much greater fat loss than slow, steady cardio and give the biggest training stimulus with the least amount of time. Doing 1 minute of sprinting followed by 1 minute of rest for as little as 10 minutes is a great time effective way to get in your cardio!

 
As with anything, if you do these sustained intensive forms of exercise purely for enjoyment and because you love it, you shouldn’t feel like you have to stop. It is the people that slog away for hours on end believing that they ‘have to’ to live a healthy lifestyle that may want to reconsider. Also, for those of you who are reading this and silently high fiving yourself as you make a mental note to pack away your exercise shoes, moderate exercise is still extremely important for good physical and mental health!
 
So is it survival of the fittest or survival of the moderately fit? 

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​References: 

1.         O'Keefe JH, Patil HR, Lavie CJ, Magalski A, Vogel RA, McCullough PA. Potential Adverse Cardiovascular Effects From Excessive Endurance Exercise. Mayo Clinic Proceedings.87(6):587-95.
2.         Patil HR, O'Keefe JH, Lavie CJ, Magalski A, Vogel RA, McCullough PA. Cardiovascular damage resulting from chronic excessive endurance exercise. Mo Med. 2012;109(4):312-21.
3.         Eijsvogels TM, Shave R, van Dijk A, Hopman MT, Thijssen DH. Exercise-induced cardiac troponin release: real-life clinical confusion. Curr Med Chem. 2011;18(23):3457-61.
4.         O'Hanlon R, Wilson M, Wage R, Smith G, Alpendurada FD, Wong J, et al. Troponin release following endurance exercise: is inflammation the cause? a cardiovascular magnetic resonance study. J Cardiovasc Magn Reson. 2010;12:38.
5.         Geliebter A, Maher MM, Gerace L, Gutin B, Heymsfield SB, Hashim SA. Effects of strength or aerobic training on body composition, resting metabolic rate, and peak oxygen consumption in obese dieting subjects. Am J Clin Nutr. 1997;66(3):557-63.
6.         Kraemer WJ, Volek JS, Clark KL, Gordon SE, Puhl SM, Koziris LP, et al. Influence of exercise training on physiological and performance changes with weight loss in men. Med Sci Sports Exerc. 1999;31(9):1320-9.