Tuesday, October 13, 2015

Can Running Damage Your Heart?

As I'm sure a lot of you know by now, neither one of us are the biggest fans of running. Up until now, the biggest reason was mainly because we weren't good at it preferred other forms of training. However, some recent research has surfaced that has given us one more reason to not like running (disclaimer, running is a perfectly suitable form of exercise and training we are just jealous of elite runners).  A recent article published by a research cardiologist examined life-long runners and their risk of dying from heart related issues.  What he found was actually rather startling....

I'm sure most of you (myself included) have always believed that regular exercise is good for you and will increase your lifespan.  On the flip side, if you sit around all day doing nothing, you probably have a higher risk of developing diseases, particularly cardiovascular disease, and therefore may not live as long.  A recent article titled: "Run for your a comfortable speed and not too far" found some rather contradictory evidence that this may not be always be the case.  Everyone has probably heard of random stories where individuals may have collapsed and died during/following athletic events or bouts of exercise EVEN THOUGH they were thought to have been in excellent shape.  A lot of these cases are believed to have been caused by underlying genetic conditions (i.e. hypertrophic cardiomyopathy), which is the leading causes of cardiac death in athletes.  However, there may be more to the story.

In the previously mentioned article, it stated:

"High-intensity exercise sessions lasting beyond 1–2 h cause acute volume overload of the atria and right ventricle (RV), which can bring about overstretching and micro-tears in the myocardium, as evidenced by a transient rise in cardiac biomarkers." 

Basically this is saying long-term intense exercise (aerobic) can actually cause damage your heart. This kind of goes against everything we have been believing for years, right?  The authors did explain that the acute damages seen following the intense exercise does revert itself and things can go back to normal within a few days.  However, they also explained that if high-intensity or high-volumes of exercise are sustained for multiple hours a day for multiple days/months/years (i.e. marathon runners) the damage can add up and actually speed up the "aging" process of the heart!  In the graph below, it shows an individual's risk of dying, dependent on how many miles a week they run  The red bar on the far left represents a sedentary individual who has the highest risk of dying.

On the other end of the spectrum, there are 2 red bars representing people who run 20-25 miles and more than 25 miles a week and they also have a relatively high risk of dying....wait, what? A sedentary person has the same risk of dying due to disease as a life-long marathon runner who is in excellent shape!?

So what's the deal? Is endurance exercise really bad for me? The answer is no. Exercise is probably the single most effective way to extend your life.  However, as with everything, it's all about moderation!  The figure below shows an individual's % reduction in all-cause mortality on the y-axis as a product of the hours spent exercising (x-axis).

Based on this figure it appears as though the longer you exercise, the less likely you are to die of a disease.  However, this increase seems to reach a plateau around 40-50 min for vigorous exercise and ~100 min for light-moderate exercise.  In other words, if you are exercising at a high-intensity you really won't receive additional benefits (in terms of increasing lifespan) if you exercise for more than an hour at that intensity. So, if you are running at high-intensities for extended periods of time, make sure you give your body (specifically your heart) some time to recover from the high amounts of strain placed on your cardiovascular system.  Your heart, as with any other muscle in your body, needs time to recover when high amounts of stress/strain are placed upon it during exercise.  You wouldn't go to a gym and do 500 squats everyday for 15 years would you? No, because your legs and back would hate you forever and you would probably begin to have major complications due to overtraining and the high amounts of stress placed on your legs.  As with strength training, too much volume or training at too high of an intensity for an extended period of time can have detrimental effects on the body.  The same goes for high-level endurance training as recovery is just as important as the training program itself!

Read the full article here

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