How is the energy expenditure calculated?

To calculate the energy expenditure (refer to this link under "energy_mifflin_keytel"), Hexoskin uses a formula that considers your age, gender, your HRmax and your HRrest (equation for Mifflin-Keytel). Your HRmax and your HRrest are calculated when you complete the Fitness Tests in the Hexoskin App.

The updated equation for Mifflin-Keytel is the following:

Energy consumed based on the heart rate. Estimated using the heart rate, sex, age and VO2_max.

Below hr_rest, the equation is based on basal metabolic rate measured by Mifflin St Jeor Equation*.
Above hr_max * 0.6. The equation is given by the Keytel equation**.
Between hr_rest and hr_max * 0.6. The equation is the ponderated sum of basal metabolic rate Mifflin St Jeor Equation and of Keytel equation measured at hr_max * 0.6.

Energy consumemen (watt) = Mifflin * (hr_max * 0.6 -HR) / (max_hr * 0.6-hr_rest) + Keytel(hr_max * 0.6)* (HR-hr_rest)/(hr_max * 0.6-hr_rest)

Mifflin St Jeor Equation :

Energy consumemen watt = 0.048379 * (10.1 * weight + 625 * height - 5.0 * age + 5)
Energy consumewomen watt = 0.048379 *(10.1 * weight + 625 * height - 5.0 * age - 165)

Keytel equation:

Energy consumemen (HR)watt = (-59.3954-36.3781+0.271*age+0.394*weight+0.404*VO2_max+ 0.634*HR ) *16.66Energy

consumewomen (HR)watt = (-59.3954+0+0.274*age+0.103*weight+0.380*VO2_max+ 0.450*HR ) *16.66

Where:

HR is the instantaneous heart rate in beats per minute,

weight is in kg,

height is in meter,

age is in years.

hr_max, hr_rest and VO2_max are defined in the userprofile.

References:
*Mifflin, M. D., St Jeor, S. T., Hill, L. A., Scott, B. J., Daugherty, S. A., & Koh, Y. O. (1990). A new predictive equation for resting energy expenditure in healthy individuals. The American Journal of Clinical Nutrition, 51(2), 241–247.
**Keytel, L. R., Goedecke, J. H., Noakes, T. D., Hiiloskorpi, H., Laukkanen, R., van der Merwe, L., & Lambert, E. V. (2005). Prediction of energy expenditure from heart rate monitoring during submaximal exercise. Journal of Sports Sciences, 23(3), 289–297.

Please note that Hexoskin automatically calculates the energy expenditure for every second (sampling rate 1Hz). You will find the data in the file under "energy_mifflin_keytel.wav" whenever you download the record/activity.

Please note that if you haven’t completed the Fitness tests from the Hexoskin App, Hexoskin algorithms will use the theoretical values for HRmax and HR rest based on your demographic profile to calculate your energy expenditure.

This means that:

1) HRmax will be calculated by this equation --> HRmax = 208-0.7 * age

2) HRrest will be based on the age of the user --> You will find the default value for your user (or participant) in the Hexoskin Dashboard under the "Health Status" tab > under "Resting Heart Rate"

3) HR in the formula is the HR detected by the Hexoskin cardiac sensors and updated every second.