Heart rate trust issues

  • Creator
  • #42027

    Hi everybody,
    On todays run I made an interesting discovery;
    I just recently bought a new chest strap, since I lost my previous one.
    Before todays mountainrun I licked the electrodes to get them wet (i dont always do that) and immediately I noticed my heart rate was around 4-6 beats higher than normal, even though I was well rested and felt great. The heart rate readings just seemed higher for the same aerobic pace I was normally running.
    After 40 min or so, the HR readings went down 3-4 bpm, even though I still maintained the same pace and intensity. Now everything seemed to be in order again for the next 50 min, the intensity that i felt matched the HR readings like normal.
    Then I took off my strap to check the elecrodes; they were slightly moist.(it was a warm day) I still gave them another lick, put the strap back on, and ta-da, my HR went up like 4-6 bpm, like at the start, even though I maintained the same intensity.
    Now I’m actually quite concerned that in the last couple of months all those HR readings were actually 5 or 6 bpm higher than I thought, which would mean I spent hundreds of hours training just above AeT, not just below it.Which is also weird, I recover very well from my supposed base trainings (i train around 14-15 hours per week)And my aerobic pace usually does feel pretty easy (conversational pace)
    What do you guys think about that? Is it common for chest straps to be this inaccurate when their not wet?
    Another thing, if I train 2-3 bpm just above my AeT does my aerobic system not benefit from that anymore? It feels hardly any different than my AeT pace.
    Hopefully I can get some insight from you guys 🙂
    Greetings from Switzerland

  • Participant
    thierryw203 on #42028

    I am having the same issue too. I’ve been focusing on own RPE and not my HR monitor. This way I feel like I’m not going crazy.

    Garret on #42043

    Hi Ben

    I think it could depend on how you determine your AeT.

    If you determined your AeT using the same strap and you wet and wear it the same way for your AeT tests and your runs any error may well be in both your AeT value and your running HR values.

    If you test your AeT frequently any errors, either positive or negative, will tend to even out over time.

    The pinned post at the top of all the forms references studies that show chest straps are very accurate.

    – Garret

    Anonymous on #42046

    I’m not sure I can shed any light on whether your chest strap is working properly or not. Our experience is that Polar straps are the best and you can snap on some of the Garmin and Wahoo monitors to Polar straps. Garmin straps are pretty especially the one with the built in monitor that has a red border. Suunto straps get the worst feedback from folks I know that use them.

    Having a higher than normal HR with a lower than normal perceived exertion is a good sign. It means you were well rested and ready to train. The opposite (low HR and high PE) is an indication you are carrying significant fatigue. I like to use PE and HR rather than relying strictly on HR or strictly on PE. I talk about this in the books. HR is only a so-so metric of intensity but it is still a metric that reflects a lot about fitness and recovery state. Just using it the way I mention in the above sentence can inform your training decisions for the day. If during the warm up you HR seems elevated but you feel fast relative to the effort that would probably be a good day to do a harder or longer workout. If during the warm HR is low unless you make a big effort you are tired and should do a recovery day.

    I doubt that all your hard work of the mast months is wasted. AeT HR can move around several bpm depending on recovery state.


    Anonymous on #42095

    In addition to Scott’s comments beware of trying to be too precise. HR is a fudgy metric at best. If you’re within 5-6 BPM, I’d say your HRM is accurate enough.

    Ben on #42104

    Thanks a lot for the replies! I have actually done a lab test earlier this year, which set my AeT at 153 bpm. If I remember correctly, they didnt moisten the HR belt for that, and I always assumed my sweat should be sufficient to get accurate readings.
    Also, In most of my base trainings I try to keep HR below 150, just to be sure, so I assume I was still below AeT even if the HR readings were a bit off.

    Michaeltyoung on #42155

    I’ll second Scott’s comment about the Suunto heart rate monitor having issues. I went through 3 new HRMs and new straps and kept seeing occasional periods where the heart rate is too high by like 20-30bpm. I honestly believe there’s a bug in their software. The Suunto monitors are a little bit more complicated in that they have a feature that allows the monitor to save data while swimming and send to the watch once you’re out of the water, but more code means more places for the code to break.

    In any case, once I switched to a wahoo hrm I stopped seeing that issue entirely. I still use the Suunto Spartan ultra and it works fine with non-suunto brand Bluetooth heart rate monitors.

    hiker on #42209

    I also have found the Suunto heart rate chest monitor to be inaccurate. In my case, what usually occurs is that when I increase my exertion, and my heart rate increases, my watch displays an increasing heart rate, often to above what I think is my maximum heart rate. It just climbs and climbs. I changed the battery and religiously cleaned the strap. This did not rectify the problem. I then bought a chest strap monitor and wrist display from ebay for thirty-some dollars, and it appears to be accurate, based on checking it against my carotid pulse. The brand I purchased on ebay is Ovente.

    I wish that I had not purchased the expensive Suunto Ambit 3. I have contacted Suunto, and they have not been helpful.

    brandon.macmullin on #42264

    I have had the same problem with my Suunto heart rate monitor. The sensors on the strap seem to wear out after approximately 6 months of regular use and the HR readings become wildly inaccurate. Sunnto sells replacement straps and once I replaced the strap the problem went away.

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