Atrial fibrillation Cycling Stuff Cycling Wed

Cycling Wed: Rest is best…

Dear Cyclists (or other endurance athletes),

Since your heart—a muscle, like any other muscle in your body—is at the crux of cycling performance, I thought a story on a common heart condition might be helpful.

The story involves a common cardiac condition called tachycardia-mediated cardiomyopathy.”

Now hold on a minute; don’t click away yet.  Let me explain.  Give science a chance.

First a translation: tachycardia means excessively fast heart rate (>120-140bpm–all the time), cardiomyopathy means disease of the heart muscle (in this case, a weakening of the heart muscle–a low ejection fraction.)  As it turns out, persistently fast heart rates lead to weakening of the heart muscle–as if the high rate is poisonous.

Want to study heart failure due to a weak heart muscle in the animal lab?  One model is to place a pacemaker in an animal and persistently pace the heart too fast. In a few weeks, the ventricles (pumping chambers) will weaken, and heart failure signs will ensue. A very, very common real-life manifestation of this phenomenon is the patient who unknowingly develops atrial fibrillation. The unfelt rapid heart beat progressively weakens the heart and results in heart failure symptoms. (The good news for such patients is that medical treatment often results in complete and permanent resolution.)

Other than knowing an answer in a medical jeopardy game, why is this important information for endurance athletes?

What’s your point?  Going fast requires toughness of mind and body.  We need the miles, and the intensity. Harden-up, will ya.  Have you not heard the stories on why East Africans are such good distance runners:  because they run all the time, everywhere, to school and back, for instance.  Duh, we Americans don’t run enough, that’s why we are slower.” 

That’s where the heart muscle story comes in.  Muscles, the heart included, are indeed quite malleable. Consistently placing a load on a muscle results in an increase in mass and contractility.  But the caveat is that a muscle needs time to recover and rejuvenate. Lack of rest not only disallows these favorable adaptations, it can also actually decrease performance and in extreme cases, like persistently tachycardic patients, the muscles become dysfunctional.  

No, I am not saying excessive exercise will lead to heart failure, rather, I am using a common medical condition to illustrate the importance of resting an overloaded muscle, and that the well-known manifestations of over-training have a real physiologic basis.

Muscles need rest. Hard work is a good thing, but for many cross country runners, cyclists and endurance athletes, working harder at resting is more challenging than gutting out another quarter-mile repeat or hot-lap.

It has been said many times before, but bears repeating: go hard on hard days and easy on easy days. Your muscles will like this.

Good luck with that.


5 replies on “Cycling Wed: Rest is best…”

Thank you Doc.. a common theme amongst endurance athletes. They go to hard on the easy days and subsequently can't go hard enough on the hard days to facilitate the improvements they desire

A couple of injuries has made this clear to me. Sometimes I feel like I'm a slacker for taking time, but when I do typically my performance improves. To rest is to heal, to heal is to improve.

Thanks Doc for saying it again

This is something I have always known and practiced when i was into body building but seamed to forget when i got into cycling. Ride hard all the time was my motto. Even when my affib would act up I would stop just long enough to get my heart back into rhythm and go right back to suffering.
Looking back though two things come to mind. The first is did all of this all out cycling all the time exacerbate and speed up the process of the affib. I was diagnosed a couple of years before I took up cycling but what if I had used the same techniques of hard, easy and rest days I had become so accustomed too when I was lifting. Would that have prolonged the progress of the affib. And the second is how many times I was on the edge of total cardiac disaster. I was always so focused on what I was doing that I never gave it a second thought at the time.
Needless to say rest days and easy days have become a regular part of my training regiment.

Definitely easier said than done especially if you are addicted to the endorphin rush that comes with giving it everything you've got.

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