Temperature & Calories burnt

kelika71
kelika71 Posts: 778 Member
edited September 29 in Fitness and Exercise
Does temperature make a difference in calories burnt? I believe so but are they TRUE calories??

Example: Last Friday and today, I mowed grass. I use a Polar FT7. Last Friday wasn't as hot and humid.
These are what the Polar spit out for mowing grass: Last Friday: 56 min 287 cals burnt
Today: 49 min 401 cals burnt

Do I trust the 401 since the heat & humidity are up? Or, are they like 'false' calories?

What do I do?!?!

Replies

  • MrsRobertson1005
    MrsRobertson1005 Posts: 552 Member
    Th heat makes your body work harder to keep cool so yes, real calories :)
  • mlemonroe2
    mlemonroe2 Posts: 603
    i would trust the HRM. it is the most accurate way to keep track of calories burned.
  • sophjakesmom
    sophjakesmom Posts: 904 Member
    Yes, temperature matters.
  • Azdak
    Azdak Posts: 8,281 Member
    No you do not burn extra calories in the heat. This is one of the instances where many/most HRMs lose a lot of accuracy. The increased temperature results in a higher heart rate, but stroke volume decreases so that cardiac output (and thus oxygen uptake and calories burned) remain the same.
  • Azdak
    Azdak Posts: 8,281 Member
    The issue is really 'cardiac creep.' That is, your heart works harder in the heat to perform the same activity over time spent doing it. Don't have a good explanation handy, but its my instinct that its accounted for with your measurements and doesn't need further adjusting.

    This might explain it for you http://runningtimes.com/Article.aspx?ArticleID=7892

    I recently read an interesting review that suggests that it's increased heart rate (due primarily to increase in core temp) that is the primary contributor rather than loss of plasma volume. The "decreased plasma volume = increased heart rate" has been the standard explanation for some years, but it has been shown that it is not the case.

    Essentially the effect is the same -- increased heart rate with no increase in actual workload (or calories expended).
  • marniehodges
    marniehodges Posts: 264
    Regardless of science, I'm going with YES! Sweating my *#@ off is gonna count for something :bigsmile:
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