How can a HRM calorie calc be accurate when...

wellbert
wellbert Posts: 3,924 Member
edited December 20 in Fitness and Exercise
Body composition is not factored into the calculation?

Replies

  • ArchyJill
    ArchyJill Posts: 548 Member
    Because the number of calories burned is more dependent on cardiovascular fitness.
  • dad106
    dad106 Posts: 4,868 Member
    Because they base it off the percentage of max heart rate.. IE working at 60,70,80,90,100 percent of max heart rate.
  • wellbert
    wellbert Posts: 3,924 Member
    Right. But if I'm 240lbs with 7% body fat, or 240lbs with 40% bodyfat, I'm going to burn a significantly different amount of calories, no?
  • ninerbuff
    ninerbuff Posts: 49,029 Member
    Right. But if I'm 240lbs with 7% body fat, or 240lbs with 40% bodyfat, I'm going to burn a significantly different amount of calories, no?
    It gives and approximation only. Other variables could be VO2 max, intensity, whether or not you're doing HIIT, altitude, grades of incline you may be working on, etc.

    A.C.E. Certified Personal/Group Fitness Trainer
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  • TrainingWithTonya
    TrainingWithTonya Posts: 1,741 Member
    Heart rate monitors work on the assumption that heart rate and calorie burns are linearly correlated. Unfortunately, that is only true for steady state cardio and only if the participant is not on any medications or other substances that effect heart rate. So, if you consume caffeine at any point within 12 hours prior to your workout, you're getting an artificially high calorie read too. And if you do weight training, HIIT, etc. where the heart rate is up and down during your workout, you don't have an accurate read because of not having a steady state heart rate. This is why we were taught to use METs to estimate calorie burns because they are an average of the number of times the normal metabolism is working during specific activities as measured in a lab setting with calorimetry (usually indirect calorimetry). While it is still an average estimate, it is more accurate then HRMs for people who are doing anything other then steady state cardio or are on medications of any kind.
    16 years Certified Personal Trainer and Group Exercise Instructor
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  • Azdak
    Azdak Posts: 8,281 Member
    Right. But if I'm 240lbs with 7% body fat, or 240lbs with 40% bodyfat, I'm going to burn a significantly different amount of calories, no?

    The difference is likely too small to be quantified--or the instance of someone 240lb and 7% body too small to be relevant to the general population.

    From a work standpoint, the relevant factor is mass--the work required to move 240lb is based on the 240 lb--doesn't make any difference if it is fat, muscle, or feathers.
  • SanyamKaushik
    SanyamKaushik Posts: 215 Member
    Bump.
  • patranus
    patranus Posts: 61 Member
    Right. But if I'm 240lbs with 7% body fat, or 240lbs with 40% bodyfat, I'm going to burn a significantly different amount of calories, no?
    It gives and approximation only. Other variables could be VO2 max, intensity, whether or not you're doing HIIT, altitude, grades of incline you may be working on, etc.

    A.C.E. Certified Personal/Group Fitness Trainer
    IDEA Fitness member
    Kickboxing Certified Instructor
    Been in fitness for 28+ years and have studied kinesiology and nutrition

    True, but all of those things are going to result in fluctuation in heart rate which will result in more/less calculated calories burned.
  • ninerbuff
    ninerbuff Posts: 49,029 Member
    Right. But if I'm 240lbs with 7% body fat, or 240lbs with 40% bodyfat, I'm going to burn a significantly different amount of calories, no?
    It gives and approximation only. Other variables could be VO2 max, intensity, whether or not you're doing HIIT, altitude, grades of incline you may be working on, etc.

    A.C.E. Certified Personal/Group Fitness Trainer
    IDEA Fitness member
    Kickboxing Certified Instructor
    Been in fitness for 28+ years and have studied kinesiology and nutrition

    True, but all of those things are going to result in fluctuation in heart rate which will result in more/less calculated calories burned.
    Agree, but examples of HIIT are more considered anaerobic than aerobic, so caloric burn value would be different.

    A.C.E. Certified Personal Trainer/Group Fitness Instructor
    IDEA Fitness member
    Kickboxing Certified Instructor
    Been in fitness for 28+ years and have studied kinesiology and nutrition
  • AnotherJenn
    AnotherJenn Posts: 62 Member
    My HRM asks for my height, weight and body fat % so I feel like it's pretty accurate...I hope.
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