I was curious after seeing a friend’s share of the calories he burned during a recent Orange Theory workout how these calories were calculated. I looked it up and the best information I could find was that it was probably based on the heart rates recorded during the workout and other basic information such as the workout duration (T), gender, body weight (W), age (A), and the exerciser’s maximum heart rate (MHR). The formula I found on a discussion board is Male: ((-95.7735 + (0.634 x HR) + (0.404 x VO2max) + (0.394 x W) + (0.271 x A))/4.184) x 60 x T Female: ((-59.3954 + (0.45 x HR) + (0.380 x VO2max) + (0.103 x W) + (0.274 x A))/4.184) x 60 x T.
The challenge I see with this is the maximal oxygen consumption (VO2max). This can be estimated using a number of different field tests or measured directly during a graded exercise test (stress test). The comment on the discussion board suggested that it could be calculated by: VO2max = 1.5472 x %MHR – 57.53, where MHR = 208 – (0.7 x Age). I would suspect, however, that this is grossly inaccurate. Of course, measuring oxygen consumption directly during exercise is quite challenging. (If you could manage, one expends 5 kcal for every liter of oxygen.) In addition, monitoring heart rate during exercise isn’t always possible (unless your wear a heart rate monitor and your gym does the calculating for you).
Knowing the exact caloric expenditure of your workout is great, but estimates are good enough. (Heck, caloric intake is quite inaccurate, as well.) If fat loss is the goal, the scale is going either up or down or it is stable. If it is in the wrong direction (e.g., going up instead of down), make some changes to your activity or food intake. Find your consistency. Just be active.
Be your best today; be better tomorrow.
Carpe momento!