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HR major increase with time during runs

Former Member
Former Member over 9 years ago
Hello

I have an issue which might not be a Garmin 235 issue as such but perhaps more about optical sensors and me in general.

I am 38 yo, reasonably fit and I run twice a week for runs generally between 8 and 18km.

I have had 3 watches with HR optical wrist sensors now. I have started with a TomTom Cardio multisport last year and thought the watch optical sensor was at fault and sold it. Then I bought a Garmin 225 and had the same issue. And well as Garmin released the 235 just after I purchased the 225, I bought a 235 because I am a geek ;-). Anyway all three watches have been showing the same issue.

This problem is that when I run my watch’s optical HR readings always go up steadily with time. On a steady run my HR optical reading will start at a pretty normal number (between 130 to 150 bpm depending on pace). But I can never maintain it. If I maintain that intensity the HR reading will keep going up, all the way up to over 180 bpm sometimes at the end of the run. Of course it does not feel as if my heart is pumping more as the intensity is the same. I feel no different. Only the readings go up. Even if I slow down during my run, my HR does not really go down, it will keep climbing steadily with time. What is odd is that the increase is almost linear. This is not a cadence lock as the numbers are different to my cadence. Even when I do intervals my HR fluctuates up and down fine but the long term trend is still showing a steady increase on average.

Now I know that the HR does fluctuate a bit with time as the cardiovascular system must divert blood flow to the skin to enhance heat dissipation but certainly not to the level I experience (+30/50 bpm vs same intensity level at the beginning of the run).

Although I need to point out that I have always sweat a lot when I run because my body gets pretty hot. I mean I really sweat a lot during a run as I need to combat my body heat going up. Therefore I wondered if that is not the cause of this issue for me related to the optical sensor technology. I understand that wrist optical sensors monitor the flow of blood on the wrist but when the body temperature goes up the blood vessels leading to the skin capillaries dilate. Therefore I wondered whether excessive sweating and excessive body heat could not play up with optical readings and interpretation of the blood flow? Being dehydrated and with the blood vessel dilatation, my blood flow might be altered and as a result my readings from the optical sensor. That would explain the steady increase of the readings

I never had a watch with a chest strap therefore I cannot compare or test. I'd be happy to buy one if I can be sure that optical HR readings can be wrong in my case but I do not want to buy one if that is not the case. Especially as I bought optical sensors watches to avoid having a strap

What do you think? Does anybody know if excessive body heat and or excessive sweating can cause optical readings to go up with time as the body temperature goes up or as the body gets dehydrated?

Thank you.

2 random graphs to illustrate this.

https://connect.garmin.com/modern/activity/1000385114

https://connect.garmin.com/modern/activity/981645254
  • 0 over 9 years ago
    Look like you're simply experiencing Cardiac Creep. Perfectly normal physiological phenomenon.
  • Former Member
    0 Former Member over 9 years ago
    {please delete}
  • 0 over 9 years ago
    Yep, sure looks like cardiac drift to me. Perfectly normal.
  • Former Member
    0 Former Member over 9 years ago
    It sure is. I have no doubts this applies to me. But heart rate drift is pretty marginal, isn't it? +10/20 bpm tops normally.

    But here we are talking about +30/50 bpm on slow and steady runs. This is a massive increase. And readings often go over my estimated max HRM (approx 182 based on age)

    Cruising over 180 bpm on a slow steady run for a 38 yo runner is a lot. 180+ bpm is the very top end of my anaerobic zone. I should only see it if I run uphill fast or if I sprint. Here these are slow runs which do not feel tough at all. And I do not feel my heart racing. I can talk. I recover very quickly as well afterwards.

    As I said a strap would clearly tell me whether the reading is correct or whether optical sensor watches have a flow when people suffer from hih body temp/excessive sweating. But I do not want to buy one just to test it and thought somebody might be able to confirm this (or not of course).
  • 0 over 9 years ago
    First and foremost - if you're truly concerned about something related to your heart, go see a medical professional ASAP. Especially so if you've not had a recent physical and discussed your running with your doctor. Don't seek medical advice from random Internet strangers.

    Back on topic:

    And readings often go over my estimated max HRM (approx 182 based on age)


    So what?

    Even the most complicated formulas for maxHR are bullsh!t for anything other than what the average is for a set of parameters. The 220-age is even worse bullpucky.

    Do you worry if your shoe size is different from the average? Of course not. So why worry about another parameter that varys substantially between individuals?

    Cruising over 180 bpm on a slow steady run for a 38 yo runner is a lot. 180+ bpm is the very top end of my anaerobic zone. I should only see it if I run uphill fast or if I sprint.


    You really can't asses what your HR "should" be unless you truly have a good idea of your maxHR. Your zones are similarly meaningless without haveing a decent idea of your real maxHR. Which I don't think you do at this point, so you can't really make a judgement call until you do.

    Look into the methods of estimating/measuring maxHR and use those to find your maxHR instead of the average for people your age/size/whatever. Just like shoe sizes you may be well away from the averages yet still be completely normal. Just remember, any method of estimating maxHR is worthless if it doesn't involve a lot of sweat you probably feeling like you're going to puke. (also, again I'll say you need to have had a chat with your doctor about your running if you haven't previously done so; do any maxHR tests where someone can get you help, better safe than sorry)

    Now with all that said, your HR graphs look normal enough. It takes a bit to warm up, so you really can't assess HR in the first few minutes. Once warmed up the raise to the end seems normal enough. Dehydration will certainly cause an HR increase; Mr. Google will lead you to lots of info on that correlation.

    Again, I'm not seeing anything out of the ordinary. (and go back to my first statement about medical advice from random Internet strangers... my advice is worth every penny you've paid for it.. :D )
  • Former Member
    0 Former Member over 9 years ago
    190

    Besides what everyone else has said about cardiac creep, you said it does not physically feel as if your heart is beating at 180bpm? That's unusual in my experience. When my heart rate gets up that high, I am really pushing hard and it's evident in my breathing and my pace. Out of curiosity, what is your VO2 max estimation from Garmin (in your watch go to activity->menu->my stats->V02 max)?


    You said you will run as many as 36K a week in two runs... First off, I'm not a coach and by no means an expert so take this as you will knowing that, but I think it would be better to spread that distance into 4+ runs and I think your body would probably adapt better to the distance. I currently run a similar distance to you... about 6.5K (4 miles) every weekday alternating my speed on those days between threshold and recovery and then I'll go for an easy 15 to 20K on the weekend. My body/heart likes doing 5 to 6 runs spread out a lot more than trying to do it all in two or three runs. You might have similar success doing it like that.
  • 0 over 9 years ago
    It sure is. I have no doubts this applies to me. But heart rate drift is pretty marginal, isn't it? +10/20 bpm tops normally.

    But here we are talking about +30/50 bpm on slow and steady runs. This is a massive increase. And readings often go over my estimated max HRM (approx 182 based on age)

    Cruising over 180 bpm on a slow steady run for a 38 yo runner is a lot. 180+ bpm is the very top end of my anaerobic zone. I should only see it if I run uphill fast or if I sprint. Here these are slow runs which do not feel tough at all. And I do not feel my heart racing. I can talk. I recover very quickly as well afterwards.

    As I said a strap would clearly tell me whether the reading is correct or whether optical sensor watches have a flow when people suffer from hih body temp/excessive sweating. But I do not want to buy one just to test it and thought somebody might be able to confirm this (or not of course).


    In addition to what gpb11 said it's really hard to say much about what a given HR means to an individual. Two people of the same age and relatively similar fitness 180 could be 10k pace for one and 5k pace for the other. According to age based formulas my maxHR should be somewhere between 168 and 173 but I've measured it 190+ during 1 mile races on the track.

    Since your examples seem to have done on a treadmill here's one I did recently. The speed on the treadmill was the same for the first hour despite what the pace graph shows, which is as long as the TM's at my gym will go in one session, and the slower part was a bit of a cool down after restarting. Average HR for the first mile was 128 and 152 toward the end.
    https://connect.garmin.com/modern/activity/985353673
  • 0 over 9 years ago
    In my experience significant cardiac drift is more likely to happen when
    (a) Start at a fairly hard pace and try and maintain it
    (b) Run in a fairly warm environment

    It looks like both apply here as you were on a treadmill and your training effect was the maximum 5.0.

    What happens with your HR if say instead of 9 min/miles you try for 10 min/miles and run outdoors (if possible)?

    By and large if I run "within myself" - say 90 secs/mile slower than marathon pace then on a fairly cool day my HR would not shift much at all throughout.
    If however I did a threshold run I would expect it to rise a bit throughout.
  • Former Member
    0 Former Member over 9 years ago
    Besides what everyone else has said about cardiac creep, you said it does not physically feel as if your heart is beating at 180bpm? That's unusual in my experience. When my heart rate gets up that high, I am really pushing hard and it's evident in my breathing and my pace. Out of curiosity, what is your VO2 max estimation from Garmin (in your watch go to activity->menu->my stats->V02 max)?


    Yeah that is my point. This is a slow pace run and it feels like a slow pace run. The readings are completely off. They do not reflect my

    My VO2 max estimated by Garmin is 47 but that has got no real meaning as this is based on these HRM readings which are false. So the vox max estimate is false as my watch thinks wrongly I am in the anaerobic zone very quickly even on recovery runs.

    You said you will run as many as 36K a week in two runs... First off, I'm not a coach and by no means an expert so take this as you will knowing that, but I think it would be better to spread that distance into 4+ runs and I think your body would probably adapt better to the distance. I currently run a similar distance to you... about 6.5K (4 miles) every weekday alternating my speed on those days between threshold and recovery and then I'll go for an easy 15 to 20K on the weekend. My body/heart likes doing 5 to 6 runs spread out a lot more than trying to do it all in two or three runs. You might have similar success doing it like that.


    No sorry I did not say I ran 36k in 2 runs per week. You are right, I do a variety of runs which I adapt every week as I can only dedicate 2 day / week to runnning: long, short, slow, fast, interval, etc. These runs vary and range from 8k to 18k.
  • Former Member
    0 Former Member over 9 years ago
    In addition to what gpb11 said it's really hard to say much about what a given HR means to an individual. Two people of the same age and relatively similar fitness 180 could be 10k pace for one and 5k pace for the other. According to age based formulas my maxHR should be somewhere between 168 and 173 but I've measured it 190+ during 1 mile races on the track.

    Since your examples seem to have done on a treadmill here's one I did recently. The speed on the treadmill was the same for the first hour despite what the pace graph shows, which is as long as the TM's at my gym will go in one session, and the slower part was a bit of a cool down after restarting. Average HR for the first mile was 128 and 152 toward the end.
    https://connect.garmin.com/modern/activity/985353673


    Sure but these two examples are slow steady runs. I am nowehere near 180+ bpm. Although the watch readings keeps going up with time not heart beat.