How many kilocalories per kg per hour would expend exercising at 6 METS?

Answer 1

The answer to this can only be approximated. To do it, you need to know the oxygen consumption at 6 METS. The standard assumption for this is that 1 MET is 3.5 ml/min/kg of body weight. Now you need to know how many Calories are burned for each ml/min of VO2. This again, is only an approximation, because the answer depends on assumptions about muscle efficiency and fuel burned. When the RQ (ratio of VCO2/VO2) is about 0.8, we burn about 4.8 Cal per liter of VO2 (source: ACSM resource manual). So, here we go:

6 METS = 6 x 3.5 = 21 ml/min/kg of VO2. Assume a 70-kg body weight, this gives VO2 of 1.47 l/min. Now multiply by the KCal factor to get 7 Cal per minute, or 420 Cal per hour. Putting the answer in units per Kg as requested, gives 420/70 = 6 Cal/kg/hour.

6 METS is about 3.5 MPH at 5% grade (brisk walk up slight hill).

Ken Beck

Exercise Physiologist, and

Research Scientist, Boston Scientific Corp