In order to find out the number of Calories that are burned during a workout, you can use the MET equation.
METs x 3.5 x BW(kg)/200 = kcal/min
Metabolic Equivalents (METs) are a way to indirectly measure how many liters of oxygen an individual is using when doing a certain activity. At rest, we use roughly 3.5 mL of oxygen per kg per hour. Therefore, 3.5 = 1 MET. Based on this, we can estimate the energy cost (oxygen used) of other, more intense activities like house work, roller blading and even water aerobics. In order to accurately estimate the total calories burned for this individual while doing this particular activity, you need to know the body weight of the individual as well as the MET value for the activity in question. An exhaustive list of MET values can be found here:
The MET value for ‘water aerobics, water calisthenics’ is 5.5. Now that you know this, you can plug in the individual’s weight to find out how many calories they burn per minute and then per class. So if the client weighs 150 pounds (68 kg) here is what the equation would look like:
5.5 METs x 3.5 x (86kg/200) = 8.3kcal/min
And if the class is for 60 minutes:
8.6kcal/min x 60min = 498 total calories burned per class!
More information about caloric expenditure and how to use metabolic conditioning to effect over caloric expenditure is addressed at the Metabolic Training workshop.