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A short period of running out of sync may strengthen the heart (Source: Alfred Pasieka/Science Photo Library/Getty images)

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Can you make your heart stronger?

Wednesday 6th April 2016 9:17 am

Dr Karl puts his finger on the pulse of research that suggests your heart can become stronger if it runs out of sync for a short while before its rhythm is restored.

Last time, I talked about how the heart and the lungs work together in a beautifully orchestrated dance. But sometimes, things can go wrong with the internal timing of how the blood gets shifted around the four separate chambers of the heart. And sometimes, this can lead to heart failure.

And this is a long shot — but perhaps one day, you could make your heart stronger with carefully timed jolts of electricity.

The story begins in the mid-1990s. A new treatment called cardiac resynchronisation therapy was devised — to try to fix the mistiming that can sometimes cause heart failure. Electrodes implanted in the heart were fed electricity at precisely timed intervals — aiming to restore perfect timing.

After a while, the cardiac physicians noted something very odd — and luckily, encouraging — with their patients.

Patients who had their correct rhythm restored, after (and let me emphasise after) a period of non-synchrony, often ended up with stronger hearts — as compared to other heart failure patients whose hearts had always been beating in perfect timing.

Now remember, when the timing of the heart chambers is slightly out of synch, the delivery of blood is affected — and the heart runs inefficiently. This temporary period of inefficient operation seemed to make the heart work harder and get stronger. (But that improvement gets noticed only once perfect timing is restored.)

How could causing your heart to run inefficiently make it stronger?

Well, suppose that you are training for a long-distance event. You want your heart to be as strong as possible. You’re fairly limited in the range of exercises that can make your heart stronger.

Basically, you do aerobic exercise (running, swimming and the like) — and keep on repeating. About the only variation is the so-called high intensity training. This is where you push your heart rate up really hard for a minute or so, back off for a minute or so — and again keep on repeating.

But the situation is quite different for your skeletal muscles. There’s a whole wide range of different training practices.

Consider your chest muscles, the pecs. You can do a push-up. And you can also try the flat bench press, or the angled bench press with your head or your feet higher. And don’t forget the chest fly, also called the pec fly — and there are lots more. Having access to these different training techniques can help really embiggen (make bigger) those pectoralis muscles on your chest.

If only you could do something different to your heart to make it stronger. Well, maybe you can.

Remember those heart failure patients who had their hearts run out of perfect timing, and inefficiently …

And remember, that when their hearts got kicked back into perfect rhythm by the implanted pacemakers, their hearts seemed to have been made stronger — by having a temporary period of running inefficiently.

The next step was to translate these clinical observations into a study.

Researchers put pacemakers into a few dozen dogs. First off, the pacemakers were turned up much too fast (around 200 beats per minute). Within two weeks, all the dogs were in heart failure, because of the rapid heart rate.

One group of dogs stayed at 200 beats per minute for the next four weeks.

The other group of dogs still had their hearts running at 200 beats per minute for four weeks — but on top of that had another change added. To be specific, the second chamber (the right ventricle) was set to contract much too early for the fourth chamber (the left ventricle) — while still running at 200 beats per minute. This was done for six hours a day. For the remaining 18 hours, this group of dogs had their hearts returned to running at 200 beats per minute, but in regular timing.

Finally, after four weeks, the two groups of dogs were compared.

The dogs who had their hearts run out of sync for six hours each day, were better off than the other group. At the end of four weeks, their hearts could pump blood more forcefully — as compared to the dogs who just had their hearts run at 200 beats per minute. And there were enhancements on a cellular and molecular level as well.

So, having the heart run out-of-sync and inefficiently for a short while, made it stronger in the long term.

This study didn’t sound like much fun for the dogs — but it might help us humans. Because of this interesting result in dogs, the physicians are now thinking of trialling this in humans who are in heart failure.

Maybe they should ask some elite athletes to volunteer for the study? They seem to be willing to try their hearts out to win — no matter what!

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This blog first appeared on Dr Karl's Great Moments in Science

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