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View Full Version : Does a low heart rate always mean an enlarged heart size?



Lui
July 5th, 2009, 03:53 PM
I was having this discussion with someone who says that a person with a low resting heart rate automatically has an enlarged heart.

I once had my heart checked. While my resting heart rate was around 35 bpm, my heart size was rather average. I recently read something that said that an athlete does NOT automatically have an enlarged heart.
I can't find that article anymore.

Does anyone know in what way a low heart rate has to do with the size of your heart and if all swimmers have larger hearts than average people?

michaelmoore
July 5th, 2009, 04:18 PM
A thyroid problem could also cause a low resting heart rate. If your body temperature when you wake up is normally under 98 degree and you have the low resting heart rate, the next time you see your doctor and have blood work up, ask to have your TSH checked.

-michael

nhc
July 5th, 2009, 04:23 PM
I don't believe low heart rates means larger heart, though I'm no doctor. I've read that regular swimmers have lower heart rates, which is a good thing, a sign of healthier heart. After I took up swimming my heart rate lowered to around 50 from the 60's. But I'm not sure if 35 is OK, maybe it means you have a very healthy heart.

JimRude
July 5th, 2009, 04:29 PM
No, it does not.

Lui
July 5th, 2009, 04:29 PM
A thyroid problem could also cause a low resting heart rate. If your body temperature when you wake up is normally under 98 degree and you have the low resting heart rate, the next time you see your doctor and have blood work up, ask to have your TSH checked.

-michael

My heart rate is obviously the result of swimming. If I take a break for a couple of months my heart rate goes up to 60 bpm. As soon as I pick up swimming again, my heart rate goes down again.
I think if you train 4000-5000 yards a day and do a lot of cycling on the side it would be astonishing if you DIDN'T have a low heart rate.

My question wasn't really if swimmers have a lower heart rate(which they usually do) but rather if they automatically have an enlarged heart when they have a low heart rate.


No, it does not.

Well, my resting heart rate of 35 bpm was 15 years ago and I'm still alive.;)
My average resting heart rate these days is around 45 bmp. A lot of athletes have a resting heart rate of 35 or even lower though.

poolraat
July 5th, 2009, 08:56 PM
When I was in my 30's and a runner (doing 60-70 mi weekly) my resting heart rate was in the mid 40's. I quit running about 23 years ago and started swimming 9 years ago. My resting heart rate is now in the mid 50's. I'm not a doc either, but I think a lower heart rate is mostly due to the type and length of exercise we do. In some poeple it could be due to an enlarged heart but I don't think a lower resting heart rate of a conditioned athlete would be the result of this condition.

mermaid
July 5th, 2009, 10:56 PM
lower heart rate generally means better physicall fitness not large heart. however, it you want to be big hearted . . .
seriously, I don't measure my heart rate, my satisfaction comes when the nurse can't find my resting pulse . . . because it's so faint and soft

james lucas
July 6th, 2009, 02:22 AM
I'm not a doctor nor any sort of medical professional, so I'm speaking as a everyday person from personal experience.

When I'm in shape, I tend to have a low resting heart rate. 40 years ago, it tended to be under 50 beats per minute when checked first thing in the morning, before getting out of bed. As I have started to get back into shape since I started masters in October 2007, my resting heart rate has fallen from the low 60s to the mid 50s, suggesting that a single stroke of the heart muscle is able to pump more blood. My blood pressure, meanwhile, has tended to fall into the normal range as I swam more. A variety of medical imaging tests, conducted both before and after I started swimming masters, showed no enlargement of my heart muscle. My personal experience tells me the answer to this question is: no, the two should be unrelated.

swimshark
July 6th, 2009, 10:34 AM
Not a doctor here, either so this is from personal experience.

No, it does not mean enlarged heart but it can mean heart issues. My dad has a low heart rate. For him it was especially low when he had a major blockage and needed a bypass (which he got). He tracks his with a heart rate monitor.

For me, I am the opposite. I have a high resting heart rate and I have a thyroid condition. My heart rate went up when the thyroid condition came. So thyroid can cause either low or high heart rates.

jim thornton
July 6th, 2009, 11:04 AM
I am not a doctor either, but I believe I could pass in parts of Appalachia as a beloved "fake doctor" whose patients love and defend him even as the authorities are putting him in the paddy wagon en route to trial.

With this as preamble, I have written about some of the changes that the heart undergoes in reaction to heavy exercise. The basic concepts are these:

Strength training--because of the incredible high blood pressure generated by heavy dead lifts, world class weight lifters tend to develop thicker heart chamber walls, the better to withstand these pressures. People with untreated high blood pressure often get a condition called LVH, for left ventricular hypertrophy--a similar, albeit pathological, thickening of the wall of the left ventricle. It appears that when such thickening occurs in reaction to weight training, it's not harmful. When it results from untreated hypertension, however, it is harmful. Anyhow, wall chamber enlargement is one form of cardiac remodeling. It does not affect heart rate.

Aerobic training--endurance sports requires large volumes of blood being pumped through your body to supply the demands of the skeletal muscles that are doing the work. With enough training, endurance athletes can undergo all sorts of adaptations. For instance, they actually increase their blood volume and may undergo the formation of collateral vessels to better supply different parts of the body (including the heart) that need oxygen and nutrients. In terms of the heart itself, the major change is that the interior volume of the pumping chambers can enlarge. This allows the heart to pump more blood per single beat. Pure aerobic athletes don't see the enlargement, or thickening, of the heart walls per se. But they can get more expandable pumps.

Thus one reason your heart rate goes down at rest is that a single beat is circulating more blood than it used to, meeting your body's needs.

Final note: All of the above notwithstanding, to get a significant remodeling of the heart--either thickened walls or enlarged pumping chambers--requires very hefty amounts of exercise, much more than even dedicated masters swimmers are likely to do. Think Lance Armstrong, who has 2 liters more blood than most of us mortals; or Bjorn Borg in his prime, whose resting heart rate was measured at 28 beats per minute.

Lui
July 6th, 2009, 12:43 PM
Final note: All of the above notwithstanding, to get a significant remodeling of the heart--either thickened walls or enlarged pumping chambers--requires very hefty amounts of exercise, much more than even dedicated masters swimmers are likely to do. Think Lance Armstrong, who has 2 liters more blood than most of us mortals; or Bjorn Borg in his prime, whose resting heart rate was measured at 28 beats per minute.

Nice explanation. While I was reading your post I was actually thinking of Lance Armstrong. I think he has a heart that is twice the size of an average heart but cycling long distances is a lot different than swimming.

I used to work as a bike messenger. That meant cycling about 60-70 miles and 10 hours per day, five days a week. I never had myself checked back then but it would've been interesting to see if my heart was any larger than usual.

lefty
July 6th, 2009, 01:03 PM
A lot of athletes have a resting heart rate of 35 or even lower though.
___________________________________
I think if you train 4000-5000 yards a day and do a lot of cycling on the side it would be astonishing if you DIDN'T have a low heart rate


I have emailed my doctor becuase I doubt that these statements are accurate. I'll let you know...

Lui
July 6th, 2009, 02:27 PM
I have emailed my doctor becuase I doubt that these statements are accurate. I'll let you know...

I know that I definitely used to have a resting heart rate of 35 bpm because I was checked by a cardiologist. Actually 35 was my lowest heart rate measured. Usually it was more around 40-43.

Here is what I found about the topic with the help of Google:

"Values range from 28 for elite athletes to as much as 100 for the very sedentary Known as a marker of fitness "
http://findarticles.com/p/articles/mi_m0NHF/is_2_18/ai_86706813/

"Elite athletes commonly have lower resting heart rates, some as low as the high 20s." http://www.thatsfit.com/2008/02/17/your-resting-heart-rate/

"Miguel Indurain, a Spanish cyclist and five time Tour de France winner, had a resting heart rate of 28 beats per minute, one of the lowest ever recorded in a healthy human." http://en.wikipedia.org/wiki/Heart_rate


Additionally I also read on a triathlete board that many members had a resting heart rate around 30-35.
Having said that, although I had a resting heart rate of 35 bpm, it doesn't automatically mean that I was fitter than another athlete who might have a resting heart rate of 45-50 bpm.

lefty
July 6th, 2009, 03:18 PM
No offense, Lui, but you sited two people who simply stated opinions, Wikipedia and a triathletes forum. Not exactly good sources.

I am not doubting your personal story at all. I believe that your heart rate was 35. But that is no where close to the norm and I do not think that someone should expect that simply because they excercise alot.

Lui
July 6th, 2009, 04:40 PM
But that is no where close to the norm and I do not think that someone should expect that simply because they excercise alot.

What I don't get is why you mention this. My original question was if it is true that the size of an athlete's heart increases if he has a low resting heart rate.
I never claimed that people should expect these really low heart rates from exercising. There are elite athletes with a resting heart rate around 50 and others around 30. It doesn't mean one athlete is better conditioned than the other.
All I said is that it is not uncommon to have a resting heart rate of 35 after several people denied this. Just google "Elite Athlete Resting Heart rate" and you will find loads of sites that confirm this. Maybe you don't consider Wikipedia as a good source but it just mentioned that the cyclist Miguel Indurain has the lowest heart rate on record which is a fact. Lance Armstrong's heart rate is around 32-34.
I used to also do a lot of cycling which might be a reason my heart rate was that low. I always found with mainly swimming my average resting heart rate was slightly higher than with cycling.

jim thornton
July 6th, 2009, 05:42 PM
Lefty, for what it's worth, I once measured my heart rate, first thing upon awakening, before getting out of bed, at 38. It might have been lower, but I got so excited by the prospect of beating 40 that I could feel it speed up a bit towards the end of the minute.

My father, who was a reasonably regular exerciser (tennis), had a lifelong low heart beat, and I am sure that some of this is genetically mediated. However, I do think that Lui's 35 is not all that difficult to believe, especially if he had been training a lot for a long period of time.

By the way, if you look at the first link he sent, it was from (The American Journal of Epidemiology, 1999, Vol. 149, No. 9, pp. 853-862)--not that suspect, really.

As far as Wikipedia goes, it seems to me I have come across academic studies that have found the info here to be as accurate as that found in the Encyclopedia Brittanica.

jordangregory
July 6th, 2009, 11:49 PM
Let me throw in my two cents:
I would consider myself an expert in this area. I didn’t look anything up in a book or on the internet to write this post. I am just going off years of schooling and experience.
Having an "enlarged heart" isn't necessarily a bad thing. For non-athletes, it is typically bad. There can be many reasons the heart gets larger. It can be due to bad stuff like high blood pressure (and many other things) or it can be due to good stuff like exercise.
As far as the original question of the heart rate going down being due to an enlarged heart (that is one possible reason):
If your heart pumps more blood with every beat (it is larger and/or stronger), it doesn't need to beat as many times per minute. So yes, an enlarged heart, which would not be bad in the case of an athlete, can cause you to have a lower heart rate.
Also, as you train athletically, your muscles get better and pulling oxygen out of the blood. This could lead to a lower heart rate as well.
As far as what heart rate is too low, I would say that it depends. Your heart just needs to pump blood around to your body. If that happens at 20 beats per minute, that is fine. Heart rate isn't important, blood getting to your organs is.

3strokes
July 7th, 2009, 07:15 AM
Borg's physical conditioning was legendary as he could outlast most of his opponents under the most grueling match conditions. He is the most famous athlete known to have bradycardia, with a heart rate at rest reported to be between 30 and 45 beats per minute.

dorothyrde
July 7th, 2009, 07:52 AM
I loved watching Borg. He was amazing.

A low heart rate does not cause an enlarged heart. You have it turned around. The enlarged heart can be caused by what Jim talked about above, either exercise, and being very fit, the heart is a muscle, it will gain in size, especially the left ventricle, or disease.

When the heart you are fit from exercise, there is all kinds of physiological developments that can then lower your resting heart rate. Also there is a genetic component.

If you are concerned about it, get checked out by a doctor, especially if you are getting older. If they say you are fine, don't worry about it.

As far as being that low, I know many of the teens that my children swim with that have low resting HR. When you are consistently fit, it goes way down.

swiftytodd
July 8th, 2009, 04:38 PM
I started swimming and exercising just 4 months ago after a few years off and my resting heart rate went from 90 to 70.