Garmin showing heart rate plummet during workout

LotusCass
LotusCass Posts: 145 Member
edited January 2020 in Fitness and Exercise
This has happened a few times now, so today I monitored to see what was happening. I did a fairly intense, mostly weights but also cardio workout, and my Garmin vivofit recorded my heart rate dropping a lot during the workout (dee image below). At this point I was doing push ups and can tell you my heart rate was soaring, definitely not dropping. It seems to happen if I’m not doing intense cardio continuously, so when I move on to more resistance activities. Has this happened to anyone else? What can I do to stop this?

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Replies

  • dewd2
    dewd2 Posts: 2,445 Member
    Wrist based HRM's have issues. Your wrist was no doubt flex and/or moving alot while you were exercising causing the monitor to stop recording accurately.

    Is there a reason you need HR info? If you are using it for training then a HRM strap is best. If your just curious then be aware of the limitations.
  • AnnPT77
    AnnPT77 Posts: 34,267 Member
    And if you're using it for calorie estimates, it's likely to overestimate for strength exercise anyway . . . possibly by a good-ish lot, sadly.
  • sijomial
    sijomial Posts: 19,809 Member
    Why are you at all interested in your HR during resistance exercise?
  • LotusCass
    LotusCass Posts: 145 Member
    I like to record my exercise and eat back half the calories as I’m set to minimum exercise. I’ve been doing that for 8 weeks now and based on my loss it seems to be fairly accurate when it actually records my HR.
  • NorthCascades
    NorthCascades Posts: 10,968 Member
    "What can I do to stop this?"

    Wear a chest strap. Pair it to your watch.
  • sijomial
    sijomial Posts: 19,809 Member
    edited February 2020
    LotusCass wrote: »
    I like to record my exercise and eat back half the calories as I’m set to minimum exercise. I’ve been doing that for 8 weeks now and based on my loss it seems to be fairly accurate when it actually records my HR.

    What does "set to minimum exercise" mean?
    (You do know that the activity setting and purposeful exercise are completely separate items in MyFitnessPal methodology and the exercise goal in your set up has no bearing on your calorie allowance?)

    HR during resistance exercise isn't an indicator of calorie burn - the HR elevation isn't due to aerobic demand.
    Or does your Garmin have a strength training mode you can set for the dureation of that part of your exercise?
    (Some more clever algorithms are available on some devices to interpret the differences between aerobic and strength exercise.)
  • Jthanmyfitnesspal
    Jthanmyfitnesspal Posts: 3,522 Member
    That HR curve looks like it could match your description of your workout. While push-ups are hard for most people, they involve a small muscle group, so they may not tax your cardiovascular system all that much. And you don't do them for all that long. If you want to elevate your HR for an extended time you have to do cardio: running, cycling, swimming, etc.

    When I do a weight set, I time it and log it as "Cardio: Circuit Training" in MFP. It's not at all accurate, but it reminds me that I did it! I always try to be a bit conservative in eating those calories back!

    Also, if you ever want to check your watch's HR measurement, count your pulse for 6 seconds and multiply by 10. I've always found my Garmin to be spot on.
  • mmapags
    mmapags Posts: 8,934 Member
    It sounds like you are assuming an accurate heart rate during your pushups would give you an accurate calorie burn but that is not the case. Heart rate as a proxy for calorie burn is only reasonably accurate for steady state cardio. It's useless for pushups or any other resistance work.
  • fourtotwentychars
    fourtotwentychars Posts: 36 Member
    NorthCascades wrote: »
    "What can I do to stop this?"

    Wear a chest strap. Pair it to your watch.

    This also happens with the chest strap if you get it really drenched in sweat.
  • BrianSharpe
    BrianSharpe Posts: 9,248 Member
    fourtotwentychars wrote: »
    NorthCascades wrote: »
    "What can I do to stop this?"

    Wear a chest strap. Pair it to your watch.

    This also happens with the chest strap if you get it really drenched in sweat.

    Not if it's snug enough...by the time I'm finished a triathlon I'm about as drenched in sweat as can be and don't have the same issues when wearing a chest strap (necessary for recording HR during the swim) as I do when I rely on the wrist readings.
  • TravisJHunt
    TravisJHunt Posts: 533 Member
    For the wrist one I often find the opposite, it reads high. What I've found fixes this is to wear it up higher on the arm so as folks say here, it doesn't' flex with your wrist movements. Seems pretty accurate then. So I just wear it a notch or two loser and push it up my arm. Works for me any ways. Maybe it will solve your problem.
  • Jthanmyfitnesspal
    Jthanmyfitnesspal Posts: 3,522 Member
    fourtotwentychars wrote: »
    This also happens with the chest strap if you get it really drenched in sweat.

    Only if it gets so sweaty that it falls off. Actually, the big problem with chest straps is that they are electrical in nature and need good electrical contact with your skin. Sweaty skin works better than dry skin. I used to use one all the time and it would read wonky until a little sweat built up.
  • sarabushby
    sarabushby Posts: 784 Member
    My wrist based HR can even fluctuate based on if my sleeves are up or down / light levels!
  • babyluthi
    babyluthi Posts: 285 Member
    probably a vaso vagal response if you were bearing down at the time:)
  • Jthanmyfitnesspal
    Jthanmyfitnesspal Posts: 3,522 Member
    OK, so this one is wonky, too. It looks to me like the watch was loose or something, then slipped into position at about the 9 minute mark. The HR (red) is noisier just before it drops. (Whereas my pace-- gray-- doesn't really change.)

    32b08by3id4b.png

    Note that it was cold outside, so I was wearing a long sleeve thermal shirt and gloves. It was probably being pushed around.
  • Psychgrrl
    Psychgrrl Posts: 3,177 Member
    Does it fit snugly? If it’s loose, it might not read correctly. One of my co-workers was talking about his low resting heart rate. Later, I pointed out how loose his Fitbit was and if it was making intermittent contact, it might not be giving accurate readings. He started wearing it more snugly and it went to 72 and has stayed there.

    With my Garmin, it is sometime low (compared to my Fitbit. When it should be higher, such as during exercise (by 30-40 points). I power it off and the on and then it’s fine.

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