Burning less calories after only a few weeks

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AbbyCar
AbbyCar Posts: 198 Member
in Fitness and Exercise
I've been taking an intense cardio class on Thursdays, since the beginning of January. I love it! It is challenging and does not seem to have gotten easier. However, I have noticed that the last few times I have burned 80-100 calories less per session. I am wearing a Polar FT4 to gauge calories and heart rate. Could it be that my body has already acclimated to this exercise? And if it has, why doesn't it seem easier?

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  • YoungDoc2B
    YoungDoc2B Posts: 1,593 Member
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    You're becoming more fit
  • JenMc14
    JenMc14 Posts: 2,389 Member
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    I agree that it's likely you're becoming more fit so it's less effort for you. You also may have lost some weight, and the less you weigh, the less you burn.
  • knowwhentoshutup
    knowwhentoshutup Posts: 318 Member
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    Might be time to up the intensity level. :)

    Good work!
  • DopeItUp
    DopeItUp Posts: 18,771 Member
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    It's just the way it goes. If you keep doing the same thing on a consistent basis over the course of weeks/months, your body starts to become efficient at doing said activity.
  • AbbyCar
    AbbyCar Posts: 198 Member
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    Wow! I just didn't think it would happen that fast!
  • imjenjen00
    imjenjen00 Posts: 75
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    My first thought is, is the battery in your HRM low? If not, congrats on increasing your fitness :) Now time to ramp it up!
  • DebbieLyn63
    DebbieLyn63 Posts: 2,650 Member
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    I know exactly what you mean. It is getting harder and harder for me to get my heart rate up. Being 33 pounds lighter, my body doesn't have to work as hard. And my heart is getting in better condition. So it IS a lot harder to get the same burns. It does help if I hold my 5 lb dumbbells while I do my steps and walking. The added 10 pounds really helps get the HR up more.
  • AbbyCar
    AbbyCar Posts: 198 Member
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    I just got the FT4 for Christmas so I wouldn't think the battery was low.
  • Azdak
    Azdak Posts: 8,281 Member
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    The fact that the HRM is showing fewer calories or that your HR is lower doesn't necessarily mean you are actually burning fewer calories.

    If you increase your fitness level, your heart rate will drop while doing the same activity because it now represents a smaller percentage of your maximum. Unless weight has changed, you aren't burning fewer calories -- it's just that you max has increased. The HRM doesn't know that, so it is giving your erroneous readings.

    However, when it comes to group exercise classes, mechanical efficiency can play a larger role. In this case, being able to do the moves better likely means that you ARE more efficient. However, in this case, it's still an issue of HRM inaccuracy, because the HRM was probably OVERestimating the calories before. In other words, the lower number you are seeing right now is likely what you were burning all along.

    If you find you are doing a class and it is becoming harder and harder to increase heart rate, then you need to take a good look at the class. You either need to figure some way to amp up your movements or it may be time to find anothe class.
  • Justkeepswimmin
    Justkeepswimmin Posts: 777 Member
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    Weight loss can make a huge difference, I don't know how much you lost but even 5 lbs can change - I could burn over 700 calories at my heaviest in zumba class, now I struggle to keep it over 500. Even the past 10 lbs has made a huge difference from getting 575-625 if I pushed it to now if I push it I can go maybe MAYBE 525. I think the cross training with running made the cardio in the zumba have less of an effect on calorie burn. Also it's not just about HR, does your HRM take your VO2?
  • AbbyCar
    AbbyCar Posts: 198 Member
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    Since I'm not sure what a V02 is, I don't think my HRM takes it.

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