Dangers of low resting heart rate

topcattim

Now, I'm nowhere near Lance Armstrong's 32 bpm, but I had a bit of trouble today at the hospital on account of my low resting heart rate. Not massively low, but when they took it just before the procedure (which was causing me some concern and therefore, I guess had raised my bpm slightly), my heart rate was at 48 bpm.

The procedure I was in for was quite uncomfortable and led to what they call a vasovagal episode, which I think is posh for "fainting". The medics told me that this is more likely in people with low resting heart rates, as there is less "margin for error" if their heart rate goes down.

I had always been pleased that my heart rate was quite low, although I am sure there are many on here who have much lower. But this is the first I've heard that it might not be a good thing....

davidmiller

That's a bit worrying. Last year my resting heart rate was about 60-62. The other day I got the HRM out of hiberation and sat here at my desk and watched it go down to 48.

i'll be watching this thread nervously.

DM

mgcycleguy

Well i measured my RHR a few years ago (wore my Garmin 305 in bed for a night .... lol.... better half still thinks im insane... but i got a really cool HR trace over 8hours, like a kind of long ECG readout in the morning)... anyway, RHR was low... so popped to see GP... his conclusion (apart from considering me for pychiatric evaluation for wearing a bike GPS computer in bed !) was that if you are doing a reasonable amount of training on a bike, and you have no other adverse symptoms, then a low RHR is bloody good thing, the important measiure he commented on though, was how quick your heart rate recovered to normal after excercise, the faster the better basically... but serously he said it was a good thing to pop along and see him... so my advice pop along and see your GP for a checkup if you are doing physical training...

csp

As the general population tends to have heart rates in the 70-80 bpm region, or even more, athletes can be misdiagnosed because of their low heart rates, so you should let the doctor know that you're a cyclist.

airborne_warrior

Of course a low RHR is a good thing as long as it is low through pursuing a training regime. At the end of the day it's better to have a RHR in the forties than in the seventies.

ColinJ

I haven't checked my resting heart rate (RHR) for a while. It is probably in the high 40s or low 50s at the moment because I'm carrying a lot of excess weight and it always goes up when I'm fat. When I was slimmer and fitter a couple of years ago my RHR was down in the low 30s. Interestingly, I have a history of fainting - I didn't realise that there was a connection.

I'm very squeamish and I think all of the fainting episodes have been medically-related. I think that I get really stressed out and stop breathing without realising it. I suppose low heart rate plus low oxygen isn't a good combination.

PS I also get really light-headed if I jump to my feet too quickly.

neeb

PS I also get really light-headed if I jump to my feet too quickly.

I've had that on and off since my early 20s (I'm 42 now) and always associate it with being fit and healthy. I only really get it when I have been crouching down, e.g. to look at a book on the bottom shelf in a library, and then stand up suddenly. It's basically due to the fact that your "resting" blood pressure is low (which is a good thing), the blood pools in your legs when you are crouching, and it takes your circulatory system a few seconds to catch up when you stand up quickly.

topcattim

Yes, the message I got from the medics yesterday was that it wasn't necessarily a sign of a problem that I had a low heart rate, but that it put me at risk of fainting easily. Like ColinJ, I have always been squeamish, and I've thought it was just because I'm a wuss. I can't even give blood now, as I had a "vasovagal episode" (I love that phrase!), but I'm pleased now to be able to explain that through the low margin for error.

I guess the good news is that I got a free ECG thrown in to my anticipated procedure, as they needed to check I hadn't had a minor heart attack. I was pleased to hear that they said I had the heart of an athlete....


...but she later qualifiied that to say "retired athlete"!

pbracing

neeb wrote:

PS I also get really light-headed if I jump to my feet too quickly.

I've had that on and off since my early 20s (I'm 42 now) and always associate it with being fit and healthy. I only really get it when I have been crouching down, e.g. to look at a book on the bottom shelf in a library, and then stand up suddenly. It's basically due to the fact that your "resting" blood pressure is low (which is a good thing), the blood pools in your legs when you are crouching, and it takes your circulatory system a few seconds to catch up when you stand up quickly.

+1 for that. Though I've never fainted because I know what's happening so stand still till the room stops spinning
I'm not squeemish though, was most disappointed they wouldn't do my knee under local so I could watch. Fascinated by it.

There must be lots of folk on here that get the dizzyness I'd guess.

coelecanth

I don't think that your RHR has anything to do with fainting- in a vasovagal syncope (faint), your HR goes down due to the vagus nerve being stimulated by the brainstem and a withdrawal of sympathetic tone, which causes blood vessels to dilate and your effective circulating blood volume to fall. The vagus nerve supplies the heart and reduces heart rate. You faint (ie become horizontal) to preserve blood flow to the brain.

The risk of vasovagal syncope has much more to do with age and genetic predisposition than physical fitness. You can reduce your risk of it happening again by having enough to drink if you are going to be in a situation which puts you at risk (eg having blood taken; standing on parade for hours).

The fainting when standing up is a known physiological phenomenon called the "fainting lark", and almost everyone can make it happen if they try hard enough: http://www.springerlink.com/content/x728apx1vntmrgf3/

Anonymous

Can low Heart Rate be anything to do with when you stand up sometimes you get a sudden rush of blood or something and hear weird sounds and it feels like your head is going to expload..... then you faint.... :?:

pbt150

I'm sitting in the office afraid to get up from my seat now! Damn you! Looks like a bit more procrastination for me then...

Anonymous

Once I was feeling good, rode about 11 miles to pick some aero bars up, averaged like 21mph feeling fine, got aero bars, was headwind on way home so averaged like 19mph, I got home, was fine for like 15mins, then was putting aero bars on and was arguing with my dad about them then all of a sudden I felt weak and dizzyness kicked in, same effect as I described, then I blacked out, wonder if that could be something to do with heart rate.

Bhima

willhub wrote:

Can low Heart Rate be anything to do with when you stand up sometimes you get a sudden rush of blood or something and hear weird sounds and it feels like your head is going to expload..... then you faint.... :?:

I used to get that and the doctor said it was to do with low energy levels - specifically from not eating/drinking enough. I used to get it when walking to college in the morning (without breakfast :oops: ).

STEFANOS4784

Maybe this is what caused Sheldon Browns untimely demise :shock:

mgcycleguy

Bhima wrote:

willhub wrote:

Can low Heart Rate be anything to do with when you stand up sometimes you get a sudden rush of blood or something and hear weird sounds and it feels like your head is going to expload..... then you faint.... :?:

I used to get that and the doctor said it was to do with low energy levels - specifically from not eating/drinking enough. I used to get it when walking to college in the morning (without breakfast :oops: ).

... I get it as well, usually when im getting to end of a long period of low calorie dieting... personally i think its more to do with dehydration (due to lack of food), I think the dehydration must effect your blood pressure... if you are a bit sensitive to it anyway away you go... and Roberts your mothers brother so they say.....

KKspeeder

topcattim wrote:

Now, I'm nowhere near Lance Armstrong's 32 bpm, but I had a bit of trouble today at the hospital on account of my low resting heart rate. Not massively low, but when they took it just before the procedure (which was causing me some concern and therefore, I guess had raised my bpm slightly), my heart rate was at 48 bpm.

The procedure I was in for was quite uncomfortable and led to what they call a vasovagal episode, which I think is posh for "fainting". The medics told me that this is more likely in people with low resting heart rates, as there is less "margin for error" if their heart rate goes down.

I had always been pleased that my heart rate was quite low, although I am sure there are many on here who have much lower. But this is the first I've heard that it might not be a good thing....

Having a low hr is not dangerous unless your jacked with a super-high hematocrit from epo or blood doping.... Or you have a heart condition like hypertrophic cardiomyopathy.... OR your smoking crack and injecting heroin/ other heavy sh*t.

I went in to the doctor for checkup and had a 43 last year.... It got lower at home in bed! Not unusual and a low resting heart rate is not a sign of bad health but GOOD health if your active and riding a bike. IF your smoking crack or doing heavy recreations sh*t than maybe having a large heart stroke volume could be a hindrance.

Every cycle-ist is different and some guys riding the Tour de France have as high as in the 60s. In fact, resting hr is NO gauge of your fitness really unless your only tracing yourself. There are guys with 95 VO2 max and 400 watt FTPs that have a resting hr of 65 bpm... And guys at racing cat 4 that have a 45 bpm resting hr.

IF you are fatigued or consuming drugs it will go up.... Low is not a problem unless your heart stroke volume is tiny and your not getting enough oxygen! Thats a heart condition I would have to believe.

Jay dubbleU

My RHR has been 56 since I was 18 - I'm now 62 and its still 56 - I bike, climb and walk regularly - never had any probs - I guess it has a lot to do with your metabolism or it could be genetic - my father was a roadie in his youth and a cyclist for most of his life and his RHR was similar to mine

Bhima

Don't really understand the reason why lower is better...?

I take it it's because if you are obese/unhealthy or have poor lung capacity etc (stuff cycling counter-acts), your heart has to work harder to pump the blood around your body effectively enough?

chrisw28

I've just been to the doctors about strong heart palpitations, normally in the mornings and evenings, maybe 6-7 times in the week. It lasts about 5 seconds. He said its mostly normal for people with low resting heart rates (low 50's here), and happens more often when the heart is beating slowly (explains the morning and evening palpitations).

But if you are getting strange things from your ticker, you should still go and see your doctor!

csp

Bhima wrote:

Don't really understand the reason why lower is better...?

I take it it's because if you are obese/unhealthy or have poor lung capacity etc (stuff cycling counter-acts), your heart has to work harder to pump the blood around your body effectively enough?

The heart is a muscle, training makes it stronger and larger. A larger heart pumps more blood and doesn't have to beat as often as a smaller heart to deliver the same amount of blood.

oldwelshman

Bhima wrote:

Don't really understand the reason why lower is better...?

I take it it's because if you are obese/unhealthy or have poor lung capacity etc (stuff cycling counter-acts), your heart has to work harder to pump the blood around your body effectively enough?

The heart has a difinitive number of beats per lifetime (ok average, cannot remember number but sure you could google iand find it and benefits of low hr) so it goes without saying that if yours is 20/min less than average, your heart will last longer :-)
Oh I suppose some will now say you have to increase HR to exercise to get fit, but thats only for hour or couple of hours a time, while the rest of the day is at low heart rate.

oldwelshman

My rhr is usually between 40 and 45 but one the unfortunate few occasions I have been in for ops ( too many for my liking) they always ask if I have do a lot of sport. Once when I was coming round in recovery it was 33, soon went up when pain killers wore off!!

neeb

Just as a matter of interest, is there a clear relationship between resting HR and maximum HR, i.e. will someone with a higher max HR have a higher resting HR for a given level of fitness? Is the difference between resting and max HR (at a given age) a good way to compare fitness between two people?

jthef

Do you test your RHR when you are asleep or is it only done when resting and awake?
Awake I have about 58 and I have just had a nap with the 705 running and it went as low as 49 but manly about 53.
Had a look on some web sites and for my age it looks very good seeing that I am not too fit in the cycling world.

topcattim

oldwelshman wrote:

Bhima wrote:

Don't really understand the reason why lower is better...?

I take it it's because if you are obese/unhealthy or have poor lung capacity etc (stuff cycling counter-acts), your heart has to work harder to pump the blood around your body effectively enough?

The heart has a difinitive number of beats per lifetime (ok average, cannot remember number but sure you could google iand find it and benefits of low hr) so it goes without saying that if yours is 20/min less than average, your heart will last longer :-)
Oh I suppose some will now say you have to increase HR to exercise to get fit, but thats only for hour or couple of hours a time, while the rest of the day is at low heart rate.

Now that's really got me thinking. I'm not saying I disagree with it, its just got me thinking. I wonder if, when I go for a 3 hour ride with elevated heart rate, whether the total number of beats in that day is lower than for an average person without my hopefully lowered heart rate. Clearly it is on days when I don't do that distance, but I wonder if it will be today, for example. I'm going to have to put my HR monitor on today and work it all out - very sad!

a_n_t

oldwelshman wrote:

The heart has a difinitive number of beats per lifetime

So what if I get run over by a bus tomorrow? That would slightly skew the average?

How many people die "naturally"? not many!

neeb

So what if I get run over by a bus tomorrow? That would slightly skew the average?

Exactly. Even if it is true that the heart has a certain number of beats before it fails just through wearing out (which I'm not sure I believe), this assumes that you have lived until something between 110 and 130 and that nothing else kills you first!

I don't like the idea anyway because I have a naturally higher than average HR... I have recorded it as low as 47, but it's usually in the mid to high 50s even when I'm really fit (it was in the 80s when I was unfit). It can still get up to 190-195 flat out, which is about 15 more than it should do at my age, so I'd prefer to think that I have the heart of a 25 year old rather than that my lifespan is ticking away with every beat...

Wogan

oldwelshman wrote:

The heart has a difinitive number of beats per lifetime (ok average, cannot remember number but sure you could google iand find it and benefits of low hr) so it goes without saying that if yours is 20/min less than average, your heart will last longer :-)

Sorry welshman but that's a load of nonsense. The numbers might have correlation between species but it means bugger all for an individual's lifespan.

Back on topic - a low heart rate isn't a bad thing if there's an obvious explanation for it i.e. you do a lot of cardiovascular exercise. Cardiac output (CO) is a function of your heart rate x stroke volume (the amount of blood pumped out per beat). For your average bloke, this works out at 70bpm x 70ml = 4900ml/minute, or 5 litres per minute. Do the sums and you'll see that a larger, stronger heart that pumps out say, 100ml per beat, only needs to pump 50 times to achieve the same cardiac output.

I suppose a lower heart rate might put someone at a higher risk of vasovagal syncope, especially if they were dehydrated to start with. It'll take longer for the sympathetic system to get HR and vascular tone up to speed if it starts from a lower leve.

Keep drinking and stand up slowly. You'll be fine.

PS. If the OP was consciously sedated or had an arterial catheter procedure, that's probably going to mess up your blood pressure anyway.

cougie

Yeah - I'm sure that heartbeats thing is a myth too.

neeb

I suppose a lower heart rate might put someone at a higher risk of vasovagal syncope,

While we're on that topic, and as there seem to be a few medically knowledgeable people around, is it normal to faint after an accident, e.g. a hard blow to the hip, if you immediately start walking around and pretend nothing has happened? This happened to me recently, only the second time I've fainted in my life (the first was when I had acute food poisoning on an easyjet flight - I really don't recommend that for a laugh). It wasn't actually due to falling off the bike, I slipped on a rock while crossing a stream and hit my hip and coccyx really hard (very painful, more so than the usual hip impact you get from coming off the bike). Anyway, I try to pretend I'm OK and get up and start walking, start to feel really nauseous and light headed, have to sit down, and then (according to the people I was with) completely blacked out for about 5 seconds, eyeballs rolling back, the works. After that I genuinely was completely OK, although I had trouble convincing my friends of that; they thought I had concussion (didn't hit my head but someone thought the shock could have been transmitted up the spine from the coccyx?). I think I just fainted, maybe aided by the blood rushing to the site of the impact. Has anyone else every experienced anything like this?