How RepCount Calculates Calories for Apple Health
RepCount is able to synchronize your workout data with Apple Health and contribute to your Fitness Activity Rings.
When you activate RepCount’s Apple Health support, RepCount will share information about your workout, including your bodyweight and the active energy (calorie) burn – the energy burn value contributes to your Move Fitness Activity Ring.
Apple Health Permissions
To perform this calculation, RepCount needs access to data you enter in both the workout and Apple Health:
The workout
- Must have a start date and end date (resulting in a workout duration greater than zero minutes).
- Bodyweight must be entered.**
Apple Health
- Biological sex – permission granted, must be male or female
- Height – permission granted, set to your height (RepCount does not support editing height; you can set your height in either Apple’s Health or Fitness apps).
- Date of Birth – permission granted, set to your date of birth
- Workouts – permission granted to read and write; the "Active Energy Burn" data is directly associated with the Workout.
If you do not want RepCount to calculate caloric burn and contribute it to Apple Health, deny the “Active Energy Burned” permission.
The formula
The calculation of calories burned during your workout is an estimate. Attempts to accurately assess caloric burn generally require the use of specialized equipment and measurements not easily taken by you at the gym (e.g. lean mass, fat mass, V02 max). As well, there can be a great deal of individual variation that affects calorie burn (see Lytle et al.). Exercise science and research continues to evolve equations for calorie burn estimation. Equations using the metabolic equivalent of task (MET), such as:
calories-burned-per-minute = MET x bodyweight-in-kg x 0.0175
where MET is a value from the Compendium of Physical Activities is a good generalized start, but lacks consideration for individual differences such as age, height, and biological sex. This is where approaches such as “Corrected MET” have improved potential at accurate calorie burn estimation. The Corrected MET uses your resting metabolic rate (RMR) as calculated by the Harris-Benedict equation:
Male-RMR = 66.4730 + 5.0033(height-in-cm) + 13.7516(bodyweight-in-kg) - 6.7550(age-in-years)
Female-RMR = 655.0955 + 1.8496(height-in-cm) + 9.5634(bodyweight-in-kg) - 4.6756(age-in-years)
This equation results in RMR in kcal/day, which we then convert to ml/kg/min.
RMR-min = (((RMR-day ÷ 1440) ÷ 5) ÷ bodyweight-in-kg) x 1000
We then compute the Corrected MET (note: RepCount is using a standard MET of 3.5, which comes from the Compendium of Physical Activities Specific Activity Code 02054 “Resistance (weight) training, multiple exercises, 8-15 reps at varied resistance”):
Corrected-MET = standard-MET x (3.5 ÷ RMR-min)
And now can estimate the calories burned:
Calories-burned = corrected-MET x bodyweight-in-kg x (duration-in-minutes ÷ 60)
If a workout has a cardio exercise with both duration (Minutes/Seconds) and Kcal entered, those values are considered explicitly and factored out of the estimation. You must provide both both values (or neither value); providing only one or the other could cause an incorrect result.
** If a bodyweight is not entered for that workout, RepCount will search for and use the most recent bodyweight entry in your workout history and Apple Health weight history. For best results, enter your bodyweight on the workout.
*** If RepCount is able to calculate Active Energy Burn but unable to obtain sex, height, and date of birth (age), instead of using the Corrected MET equation it will use the Traditional MET equation.