New answers tagged kettlebell
There is a calculator here, although they don't really get into how the formula is calculated. I tried 150 lbs for your weight, and 20 minutes, and indeed, it's 400 kCal. Presumably, that's at a weight enough to raise a sweat. Plugging different values into the calculator provided there, it looks like they assume you burn about 20 kCal per minute ...
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