Counting calories burned

Do you eat to run or run to eat? I enjoy eating ice cream, potato chips, chocolates and all high caloric foods but I am also very weight conscious. Thus if someone were to ask me the question my response is definitely ‘run to eat’. In fact, I try to incorporate 30 minutes of running 3 times a week so that I do not gain weight even after indulging in cakes, ice cream, chocolates etc.

Does anyone eat to run, then? Yes my husband, he is an avid ultrarunner and he ingests energy gels during his long runs. It is thus important that we know the amount of calories consumed while performing the exercise. The desired result for me is to get a calorie deficit, whereas an ultrarunner would want to limit this deficit.

During an exercise, our body needs to convert calories from the stored nutrient state to the form that can be used by the muscle cells. This process requires oxygen, as in aerobic respiration and is dependent on the delivery of oxygen via the bloodstream. Blood flow is in turn directly related to heart rate. From this relationship, we can estimate the calorie burned (energy expenditure) from our heart rate. Essentially, with increased exercise intensity our muscles must burn more calories, and so our heart must beat faster to provide the oxygen necessary to convert those calories to the form of energy that can be burned by our muscles.

Below is a step-by-step guide on how we can calculate the amount of calories burned per minute:

1.      Ensure heart rate is within 41 to 80% VO2 max using table below

The equations used to calculate calories burned cover an exercise intensity level that ranges between 41% to 80% of VO2max. Below 41% of VO2max, the relationship between heart rate and caloric expenditure is not reliable. Above 80% of VO2max, the calories burned is based on an extrapolation (i.e. an assumption that the data correlation holds outside the limits of the gathered data points) of the experimental data.

2.      Equation for Determination of Calorie Burn per 10 minutes

Male: ((-55.0969 + (0.6309 x HR) + (0.1988 x W) + (0.2017 x A))/4.184) x 10 

Female: ((-20.4022 + (0.4472 x HR) - (0.1263 x W) + (0.074 x A))/4.184) x 10

HR = Heart rate (in beats/minute) 
W = Weight (in kilograms) 
A = Age (in years) 
T = Exercise duration time (in hours)

For a woman age 37, weight 44kg, the amount of calories burned per 10 minutes follows the graph below:

For a man age 39, weight 57 kg, the amount of calories burned per 10 minutes follows the graph below:

If you'd wish to have the excel file to generate your own graph, do contact me.

References

Keytel LR, Goedecke JH, Noakes TD, Hiiloskorpi H, Laukkanen R, van der Merwe L, Lambert EV. Prediction of energy expenditure from heart rate monitoring during submaximal exercise. J Sports Sci. 2005 Mar;23(3):289-97.

Swain DP, Abernathy KS, Smith CS, Lee SJ, Bunn SA. Target heart rates for the development of cardiorespiratory fitness. Med Sci Sports Exerc. January 1994. 26(1): 112–116.

Tanaka, H., Monhan, K.D., Seals, D.G., Age-predicted maximal heart rate revisited. Am Coll Cardiol 2001; 37:153-156.