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Intermittent HR dips: cause for concern?

Old 06-12-20, 09:45 AM
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Intermittent HR dips: cause for concern?

In keeping with the recent questions about heart rate, here's something I've noticed.

I've been riding my stationary rig regularly lately, and I've noticed that over the course of an hour, I'll have about three episodes where my HR dips about 10 bpm and then bounces back. The episodes last about 10 seconds. These show up as sharp downward spikes on the graph. These are during "off" intervals, occasionally during easy "on" intervals—in other words, when I'm not under a lot of load. This is with a chest-band HRM that I believe is maintaining good contact—I don't think it's an equipment problem.

Is this a cause for concern? Anyone else see this?
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Old 06-12-20, 01:54 PM
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Cause for concern. I'm not a doctor so I don't know.

Sounds like you are saying you are at a reduced power output, so yes you will see a reduction in HR. Not sure if it comes in sudden drops. I don't use trainers though so others will have to say.

Don't shy away from a heart doctor. I wish I'd started using one sooner, just because their answers to questions I've had in the past makes a heck of a lot more sense than what other doctors are able to convey to me when I ask them about HR stuff. I'm even pleased that in general, my thoughts on a lot of the HR concerns meshed pretty well with what my cardiologist says. Other doctors were just too oblique answering the questions.
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Old 06-14-20, 10:47 PM
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Might be a glitch. I get that same issue with my Wahoo Tickr via phone apps and bike computer. I kinda doubt my heart rate really is dipping that much. It seems to happen whenever I use the drops, then increases 10 bpm or so when I sit up into the hoods or tops again. I'm betting it's just a temporary loss of conductivity.

I suppose I could use a backup HR monitor, but I'm not too concerned. I'd manually palpate an artery if I didn't need to keep both hands on the bar. That's usually the best way to check the accuracy of our various electronic doodads. I use an automated blood pressure cuff at home, but when I visit the doctor some nurses and doctors prefer the old fashioned method -- a manual BP cuff and stethoscope. Some use the automated machines. When I was in health care we used only manual BP cuffs and palpated for HR, but that was a long time ago.
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Old 06-17-20, 09:29 PM
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i've seen this too with my HRM. only on the trainer though because the app i have plots heart rate as a graph so it is easy to see. i never look that closely at the HRM data when i get back from a ride but i suspect it would hbe happening out there too. i'v eonly had the HRM for less than a year now so if real then i'm pretty sure my heart has been doing that for ages, if an artifact of the wahoo ticker that i have then i chalk that up to great technology.

if i had a second HRM i would try both and see what they both indicate. nothing like a side by side comparison.

-scott
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Old 06-18-20, 07:30 AM
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I've actually observed this with two HRMs--a Wahoo and a Garmin (it turns out you shouldn't send the transmitter pod through the laundry, who knew?).

This would be impossible to count manually. I've only got a 10-second window to do it, and the episode is halfway over before I know that it's happening, if I notice it in the moment at all. There's no way to get an accurate manual count in that time.
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Old 06-18-20, 10:03 AM
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I guess maybe I'm not understanding what your concern is in the original post. Is this just a momentary spike/dip from what the normal steady bpm is for that level of activity? If so, I'd just file it under ..... hmmm. At least until such time you can maybe show a graph of it to an actual cardiologist and ask what it might mean.

As for laundering the transmitter pod..... well for Garmin they tell you to remove it. So Shirley you jest. <grin>

I don't salt up my clothes even though I sweat gallons. So I don't do anything but rinse my Garmin soft HR strap under the faucet after a ride. I do leave the pod on then, but I don't have a hard stream of water hitting it either. Then it gets excess water toweled off and hung up. First one lasted six or so years, second and current one is four y.o. so far. If you are the type person that gets clothes so salty that they'll stand up when dry, then maybe you do need to keep laundering the strap every so often. But not with the pod attached.
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Old 06-18-20, 10:21 AM
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I've been using a HRM w/strap, Garmin and Polar, for over 20 years, every workout. I've never seen that. During rest or easy periods, my HR shows a slow and even drop during the period, eventually coming to rest at somewhere near the expected HR for that effort. It never drops during an effort. However, most HRMs do a 5-second average, and thus don't show transients.

There is a thing known as a heart "reset". On an EKG type graph it shows as a sharp up and down spike. I can feel it if I'm lying down, a sort of stumble. It resets yous sinus rhythm if something in you thinks it needs to be reset. It's normal, but totally screws up my heart signal power numbers if I'm taking an HRV reading and I have to do it over. I can see it on the HRV graph. Could be that, could be anything. One can't tell without wearing a Halter device which your cardio can prescribe for you. Could also be a glitch. Do you lick your transmitter snaps as well as the strap? You could try with a different strap and transmitter. I've been doing this long enough and have had enough glitches that I always have spares, just in case.

That said, I don't think I've ever experienced a reset during a workout, only when resting with a low HR. I don't find anything from Dr. Google about resets, but my doc told me it's normal. I had one during a physical when he had a stethoscope on me. Ka-whump.

In your case, doesn't sound like a normal reset. I shouldn't hazard a guess as to what it is.
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Old 06-19-20, 10:13 AM
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I recall drops in HR on the trainer when I took a drink of water. Don't know if it was because the lack of Oxygen coming in when drinking or something related to the cold water. Probably didn't see 10bpm drop but there was generally a drop associated with drinking.
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Old 06-22-20, 07:47 AM
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HRMs are usually more reliable and consistent when using on the trainer versus when using on the road. The reason is on the road, wind may dry out the contacts or there may be static by wind,causing the HRM to act erratic. However, on a trainer, it's reliable. I've never had my HRMs act erratically on the trainer, ever. On the road, especially on windy days, then yes.

Having said that, during your resting period, then the HR should drop immediately (within 1-2 seconds of easing up). Then HR will pick up immediately when you're on the power. This HR "on-off" pattern should be consistant, this is the key. When you see inconsist patterns, then I'd personally go see a doctor and have them use their equipment to check my heart.
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Old 06-22-20, 09:55 AM
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In case anyone's curious, I'm uploading a screencap from Golden Cheetah, showing power and HR from a recent workout. This was an easy interval session that I've done several times. I've circled the dips. There's another dip at start of an interval, before my heart rate has had a chance to catch up with the additional load.
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Old 06-22-20, 11:25 AM
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Originally Posted by adamrice
In case anyone's curious, I'm uploading a screencap from Golden Cheetah, showing power and HR from a recent workout. This was an easy interval session that I've done several times. I've circled the dips. There's another dip at start of an interval, before my heart rate has had a chance to catch up with the additional load.
interesting graph! well since I'm no cardiologist, I won't pretend to be one.
But here's just MY opinion of your data (based on observation of my own data).

1. the 2 dips at the beginning and end don't look normal to me. Since you said you've tried 2 HRM monitors, then this lessen the chance of equipment error.
2. your HR during internals 1,2,3 look normal
3. on the 4th interval, HR dips a bit past the midway point, but this could happen because you're also dipping in power (as I see it on the graph)
4. on the 5th interval, HR has a dip around the midway point and then resuming its upward trajectory. I don't think this is normal. HR should be upward moving throughout the interval if your power is consistent (which it looks to be).
5. then on the 6th interval, HR doesn't begin to move immediately at the start of the interval. On the contrary, HR even dips, and HR does not move up until you're about 1/3 way into the interval. This doesn't look normal to me.
6. 7th interval HR looks normal
7. on the 8th interval, there is again a drop in HR almost halfway through, before HR rises again to finish the interval
8. 9th interval looks normal
9. 10th interval looks to be normal

like I said, i'm not expert, but I know that my HR patterns during these sort of submaximal intervals are more smooth and exhibit less stochastic. Maybe you're just fine and all this means nothing.
How do you feel though? Any shortness of breath? any lapses of dizziness during the workout at all?
But if you have health insurance, and this concern is on your mind, then go see your doctor.
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Old 06-23-20, 08:47 PM
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i had two thoughts about this...first was breathing, i can lower my heart rate if i take 2-3 deep breaths exhaling as much as possible. i cannot do this when pushing it thogh, only when about 1/2 to 3/4 of my FTP. i can clearly see my heart rate drop, maybe not as quickly as what is in your graph but it is noticalbe.

the other thought i had is golden cheetah. i have heard of this app, is this the only one you have observed this with? while writing my own app i learned alot about the ANT+ devices. the HRM in particular has two ways to supply an application with heart rate data, the first is quite simple and just provides a current heart rate as an integer. the other way (which i use) provides a count of beats along with a time count. The heart rate is then calculated by the application rather than the HRM itself permitting fractional heart rate measurements (77.8 BPM instead of 78 BPM). but the application has to be careful about heart beat count and time count rollovers. these are just free running counters and they come in at 4 Hz (lightning fast!), sometimes these messages are lost. it is possible that GC has flubbed some of the math and this is an artifact. couple this with potential data filtering and this could just be an application problem. suggest trying a different monitoring tool. if both HRM do this then use one with GC and the other with something else and compare the results.

-scott
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Old 06-24-20, 07:53 AM
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I'm not recording in GC, just archiving and analyzing. This was recorded using Rouvy on an iPad, connected over bluetooth to my smart trainer and HRM. What GC is showing here is consistent with what I see during the workout on Rouvy's graph display.

I don't have any ANT+ devices, although I could figure out how to log a trainer ride in a different app, if that made a difference.
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Old 06-24-20, 06:59 PM
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OK. GC is just reproducing the content of the file. if you can try recording with a different app than Rouvy. bluetooth won't make a difference, it is the same data as ANT.

and just to be clear, i am not saying that Rouvy is at fault, just trying to see if it is an application bug or a real heart anomaly.

another thing to note, if you record with a different app and do not see the anomaly then that does not necessarily determine anything, could be that a real heart anomaly is there but just did not occur for that particular workout, have to be careful with results. if possible and if you still have two HRMs you could use one monitor with Rouvy and the other HRM with some other application. i think wahoo fitness is free and should pair with any HRM.
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Old 03-03-22, 09:34 AM
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Did you figure this out?

Originally Posted by adamrice
In keeping with the recent questions about heart rate, here's something I've noticed.

I've been riding my stationary rig regularly lately, and I've noticed that over the course of an hour, I'll have about three episodes where my HR dips about 10 bpm and then bounces back. The episodes last about 10 seconds. These show up as sharp downward spikes on the graph. These are during "off" intervals, occasionally during easy "on" intervals—in other words, when I'm not under a lot of load. This is with a chest-band HRM that I believe is maintaining good contact—I don't think it's an equipment problem.

Is this a cause for concern? Anyone else see this?
Just wondering if you ever figured this out? I experience the same issue. I know it is not a technical or equipment issue because I can feel it coming on before it starts, hard to describe but it is like my stomach drops. Only occurs with a Z2 workout or during a longer warm up period. Sometimes a period of an elevated HR will follow, but more commonly HR comes back to where it was at.

Thanks
Brian
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Old 03-03-22, 09:40 AM
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Originally Posted by bwilson010
Just wondering if you ever figured this out?
Never did. And FWIW, the only reason I know this is happening is because I'm watching the graph as I work out. These "dip episodes" don't feel any different to me.
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Old 03-03-22, 09:42 AM
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Shouldn't this be in the cardiology/internet-assisted-coronary-care subform?

But, seriously, folks, don't mess around with this. Get real medical advice directly from a competent allopathic physician.
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Old 03-03-22, 10:29 AM
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All, let me add to the conversation.........I forgot about a topic years back where someone correlated this in the lower HR ranges to interference with the cadence signal. Can happen with a gps or even with a computer/Zwift setup.

When the HR and cadence are within a certain range of each other, for some reason the bluetooth and/or ANT signals get confused with each other. And the HR being shown in the dips is possibly it choosing your cadence at that moment instead.

I've actually seen this live happen in warmups for Zwift workouts where my cadence is in the 90's and my HR is in the 90's to around 110 or so. I'll suddenly see my cadence jump to like 120 or 130, then fall back. Then the HR fall to 90 or so and go back to the 120/130 I know it is.

This can happen on any device with the HR/cadence thing, so changing devices might not do it. Only thing you COULD do is log a separate workout on a smartwatch using HR only then compare the file to the workout file that has both cadence and HR.

It's called "cadence lock". A few replies to this DC Rainmaker article mention it:
https://www.dcrainmaker.com/2010/04/...eart-rate.html

Apparently for running it can happen also, spiking though since run cadence is 2x bike cadence since it counts each stride............so for running your HR may go from a Z2 of 140 up to 160/170 as it locks onto your run cadence..........of about 170.
Running writings: Cadence lock: Why GPS watches have a hard time measuring heart rate during running

Personally I've seen both happen. In both cases, intentionally altering my cadence a large amount causes it to unlock from my cadence on the HR. So running I will take long slow strides and on the bike slow to a grinding out of saddle climb of like 45 rpm. Then it usually re-grabs the HR properly.
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Old 03-03-22, 10:37 AM
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Originally Posted by bwilson010
Just wondering if you ever figured this out? I experience the same issue. I know it is not a technical or equipment issue because I can feel it coming on before it starts, hard to describe but it is like my stomach drops. Only occurs with a Z2 workout or during a longer warm up period. Sometimes a period of an elevated HR will follow, but more commonly HR comes back to where it was at.

Thanks
Brian
I haven't seen this myself while exercising, only resting, but it's pretty common knowledge among geezer riders that we experience heart "drop-outs" where it just stops beating and misses a few, then picks back up. The street says it's not dangerous. That said, get a Halter device from your cardiologist and find out what's going on. I sure as hell would!
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Old 03-03-22, 12:01 PM
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Equipment artifact or a real cardiac concern? If you're feeling a symptom, I would talk to a Doc

I do not see those drops on GoldenCheetah. I use a Garmin Strap and a 1030.

I get premature ventricular contractions and sinus pauses. My PVCs go away once I get into zone 2. It is like my carbs need rejetted. I do not see dips on my HR on the Garmin or GC.
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Old 03-04-22, 06:13 AM
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Originally Posted by gregf83
I recall drops in HR on the trainer when I took a drink of water. Don't know if it was because the lack of Oxygen coming in when drinking or something related to the cold water. Probably didn't see 10bpm drop but there was generally a drop associated with drinking.
I see upward spikes in HR whenever I take a drink - when I'm not dropping my power at the same time.
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Old 03-04-22, 06:23 AM
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I've never had any of these sudden sharp "apparent" drop-outs in HR. I would look to investigate further - both tech side and medical. Are those dips from a single data value or multiple values ramping up and down? If the latter then less chance of a simple data glitch.
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Old 03-04-22, 08:13 AM
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I don't know if this would help but I would load my FIT file into GoldenCheetah or similar that has an edit feature. You can see every HR recording, second by second. If there is a dropout, it should show there.

I reviewed about a dozen of my files. I did not see a single instance of a HR dropout. (A PVC should register as a beat but my sinus pause issue would or should show up in the data). I would make sure the electrodes are tight to the chest and moist. Garmin says synthetic materials can be a problem.........?

https://support.garmin.com/en-US/?fa...V07TSGLfS0ba38
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Old 03-04-22, 08:17 AM
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To give more technical details:
  • I only observe this on my stationary rig. I think that with road riding, the signal would be too noisy.
  • Smart trainer: Cycleops Hammer 1, which infers cadence (sometimes inaccurately). I don't have a cadence sensor per se.
  • Trainer controller: iPad running Rouvy
  • Chest band: Garmin and Wahoo chest straps; have observed "dips" with both.
  • I see this happening when my cadence is in the 70s or 80s and my HR is in the 110s-120s. So I don't think cadence lock would explain it anyhow (although that is fascinating).
  • I do have an optical HR-tracking watch (Apple watch) and could try capturing data using that, but haven't done so yet.
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Old 03-04-22, 02:24 PM
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i've mentioned this before on another thread so might as well add it here, both Bluetooth and ant both share the same freq band as microwave ovens. if you have a leaky oven in use it can interfere. the lockout thing in interesting but to me it seems that burnthesheep mentions but what i don't get about that is that the data in an ANT packet contains a channel ID which is used to know from what device an ANT packet was received by. the lockout thing implies that somehow transmission screwed up to the point that two packets miraculously swapped channel IDs, unlikely i think. more likely i think the SW choked on its packet processing. it is expected that some packets will be lost since all devices transmit asynchronously.

regardless, if something interferes with a transmission such that the receiver (application) misses data there is really no telling how that application handles that. In my own application i accept the fact that packets can be lost and just do not change the value of the thing being monitored. add to that that some applications apply filtering which can cause a data value a bit of time to display its true unfiltered but steady state value. i know rouvy applies filtering like this, i can see power increase slowly compared to what i know i am putting out, and then see it diminish when i am toast. i think it has a 3 second filter or there about. can't recall in zwift.

ill also add that i have seen my heart rate drop for no apparent reason like by 5 bpm and pretty much stay there but slowly trend upwards with no change in effort. only ever see this in my own app or in zwift in (delayed) real time. i never bother to look at .fit files for out door rides becasue i do not have a power meter and would not be able to know for sure if effort changed or not.
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