Temperature & Calories burnt

kelika71

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?!?!

MrsRobertson1005

Th heat makes your body work harder to keep cool so yes, real calories

mlemonroe2

i would trust the HRM. it is the most accurate way to keep track of calories burned.

sophjakesmom

Yes, temperature matters.

Azdak

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

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

Regardless of science, I'm going with YES! Sweating my *#@ off is gonna count for something :bigsmile: