Endurance athletes

While on a run last feb. 26, I entered a dizzy spell that ultimately resulted in an ICD defib/pacemaker for ventricula tachycardia. The problem arises in my right ventricle. None of the medical people I dealt with had a clue as to what caused this to happen to my ventricle... I happened on a study published in the "Mayo Clinic Proceedings" June issue, entitled "Potential Adverse Cardiovascular Effects From Excessive Endurance Exercise" and this explained my situation to a T! Would like to hear other opinions of the article. It is available on line, make sure you go to the June issue.

4 Comments

Don

by IAN MC - 2012-07-22 04:07:55

I agree with your analysis of our present state of knowledge. I don 't think scientists have reached that " Eureka" moment when they have all the answers for the causes of cardiac electrical problems.

As you know the way science works is that someone spots that there MAY be a causal relationship between events A and B and then many further studies are done to see if the cause and effect theory holds up

This latest Mayo Clinic study is not the 1st study by any means to suggest that high endurance exercise can lead to cardiac arrhythmias later in life. Interestingly I have always thought that a disproportionate number of runners seem to feature on the PM forum.

I notice that you threw in Sudden Cardiac Arrest (SCA) at the end. I'm not sure that this has featured as much in the studies as have electrical problems.

The majority of us on here used to have healthy hearts and then we suddenly developed electrical problems , SOMETHING must have caused this to happen. Drs fob us off with the ageing process etc but I hope that in the future avoidable causes will be identified.

It is interesting to look at exactly how electricity is generated in the heart and the chemicals which are involved , then consider the things which can affect those chemicals.....but that could maybe be left for a future debate.

Cheers

Ian

Caught another one!!!

by donr - 2012-07-22 06:07:26

Ian, I knew you could not resist the bait I threw out there! (Here in the US, that line refers to a fish called a sucker. But, I was using it to refer to a man who cannot resist a good, lively discussion.)

You have probably noticed that I use the TV set analogy on several occasions. At this point in our level of knowledge, we just flat have no idea why heart's electrical systems fail as they do - any more than we know why TV set's electrical guts fail.

My hypothesis is that it is a purely probabalistic event that is more amenable to Quantum Mechanical (QM) explanation than any other. Until all the giants of QM began their ruminations in the 1920's there were many physical phenomena that we could not explain at all.

Until we get such analyses of and descriptions of the workings of the electrical glories of the heart, we are on an understanding plateau on the subject.

Our understanding of the way the brain functions falls into that category. Is it digital? Analog? Hybrid? I think that in the end we will find some sort of explanations for functioning & failure. It will NOT BE FOUND by the medical profession as we understand it today. It will be done by someone who comes out of the QM field who is capable of applying their methods of analysis to what is happening. That is because what is happening is on a sub-molecular, perhaps atomic, level - and cannot be described by macro theories.

I am especially intrigued by HOW the SA Node does its timing & the pretty darned good accuracy of its work, beat to beat over periods of yrs; and, its capability to change that timing based on needs of the body. To me, its too accurate (and precise) to be an analog function, but I scratch my head at seeing how it could be digital.

Face it - the transistor is a product of the QM thinking, & the level of size magnitude of of the electrical functioning of the heart seems to exist at that level.

This is a field that I think is going to be exciting & fruitful for all the generations that follow us. We are now the spectators - we had our chances & missed the boat. Not from lack of trying - we just had yet to develop the skills & knowledge to comprehend or describe the process!

Well, there's a speculative hypothesis for some wooly-headed researcher to take off & run with!

Don

Adverse effects on the heart

by IAN MC - 2012-07-22 08:07:58

Hi Ponch
I haven't re-read the article but I think I remember it. I have been interested for some time on what actually causes electrical problems in the heart . Most of the time Drs haven't a clue and we are told that our sinus node wears out with age as do most of our organs.

....but why does it happen to you at the age of 26 ?

There is growing evidence of some cause and effects; one of the definite causes of electrical problems appears to be intensive levels of exercise, another one is the use of certain drugs. the calcium antagonist group of drugs for example are widely used to treat high BP and they can CAUSE electrical problems in the heart.

The heart is a muscle and when muscles are exercised over and above normal levels, they thicken. The condition even has a name , " Athletes Heart " and is common among athletes or people who do hard exercise continually over the years.

It is usually diagnosed by an Echocardiogram which shows enlargement and thickening of the ventricular muscles

I was also diagnosed with it and the Dr attributed it to my crazy desire to run marathons ( which I'm now growing out of as I get older and wiser ! )

Is it harmful ? ..probably not ,and the heart does revert to normal when you stop exercising; like any other muscle would ; BUT there is strong evidence that triathletes and compulsive runners are more likely to develop arrythmias later in life and I often wonder if this is related to the heart wall thickening. Could the electrics be affected by the thickening ? I will never know why I suddenly developed atrial flutter and needed an ablation to cure it.... did the running cause it ? who knows !

Cheers

Ian

I just read it!

by donr - 2012-07-22 11:07:07

Heavy reading, at best! But an interesting study. For those interested, I've copied the first para of the conclusion next below:

"Mayo Clinic Proceedings" June issue, entitled "Potential Adverse Cardiovascular Effects From Excessive Endurance Exercise"

"Conclusion

In some individuals, long-term excessive endurance ET may cause adverse structural and electrical cardiac remodeling, including fibrosis and stiffening of the atria, RV, and large arteries. This theoretically might provide a substrate for atrial and ventricular arrhythmias and increase CV risk. Further investigation is warranted to identify the exercise threshold for potential toxicity, screening for at-risk individuals, and ideal ET regimens for optimizing CV health. For now, on the basis of animal and human data, CV benefits of vigorous aerobic ET appear to accrue in a dose-dependent fashion up to about 1 hour daily, beyond which further exertion produces diminishing returns and may even cause adverse CV effects in some individuals."

NOTE that there are absolutely ZERO inequivical conclusions! This is essentially a speculative conclusion, using the words "May," (First sentence) & "...theoretically might..." (second sentence).

I am NOT criticizing - just pointing out that this study is setting up for further definitive work to determine IF there is any substance to a hypothesis that such heavy exercise could cause electrical problems in the heart.

I love to hear long-hairs criticize a statement that something is "..all anecdotal evidence..." because then I counter with "...even the most soundly based conclusion started out as anecdotal evidence - that's what gave the experimenter the idea for the study!" OR - try this one: "...that's all speculative..."; to which ridiculous statement I reply "Every great, well -founded idea of Man started out as pure speculation!"

So, I'd hazard a conclusion at this point that we still do not have any definitive causes for SCA under any circumstances.

O)K, Ian - back to you!

Don

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