Treadmill vs. HRM calorie readings...

sfxchris
sfxchris Posts: 39
in Fitness and Exercise
So today, I finally got a Wahoo Fitness heart rate monitor.
I paired it with my phone, and got on the treadmill.

I weigh a lot (260lbs), and I'm 6 feet tall. Therefore, I burn a bit more calories than some others. For the past 2-3 weeks, I've been going hard for an hour on the treadmill, getting off sweating and out of breath, and burning 400-450 calories in the hour according to the treadmill (by "going hard", I mean like, 3.5 incline and 2.5-3 mph because I'm like really out of shape... ha).

Today, I strapped the monitor to my chest and did my workout. I only had time to do 30 minutes today, so that's what I did. Over the course of the workout, the measurements on the treadmill and my phone were almost completely different. In the end, my treadmill read a total of 230 calories burned in 30 minutes, while my phone read just under 500. Five. Hundred. What?..

I kept the app going for 2 extra minutes while my heart rate slowed down (Avg heart rate was 155) and I ended when my BPM range was under 100. By the time this was over, my calorie expenditure was 518. Umm, okay. BIG GAP.

So, I used this http://www.shapesense.com/fitness-exercise/calculators/net-versus-gross-calorie-burn-conversion-calculator.aspx

to get my net calorie expenditure (workout expenditure - idle or rest expenditure) and I was shown a net calorie expenditure of 455 calories.
Humph.
Compare that to 230 calories on the treadmill!

Long story short, I have no idea which one to trust, let alone log in MFP. The treadmill's measurement seems more conservative, and therefore more likely to me since it was only 30 minutes. Yet, like I said, my heart rate was in the upper zones continuously and I'm pretty out of shape when it comes to cardio. Plus, the heart rate monitor was strapped to my chest, and the Treadmill didn't get any measurement of my heart rate. It does, however, know how much I weigh and how tall I am since my treadmill is pretty high-end ($2500) and is connected to ifit.com .

Which should I believe?

Replies

  • sfxchris
    sfxchris Posts: 39
    Bump
  • Rokwell
    Rokwell Posts: 143
    Always go with the HRM. It is more accurate. also when you are not in your ideal shape you will burn more cals.
  • ecw3780
    ecw3780 Posts: 608 Member
    Always go with the HRM. It is more accurate. also when you are not in your ideal shape you will burn more cals.

    I agree. Treadmills are for the average person. Even if you are not average, they are never as accurate as a heart rate monitor. I would just double check all the settings for the heart rate monitor, and then ignore what the treadmill says.
  • mhouston2011
    mhouston2011 Posts: 155
    absolutely the HRM, especially with the strap picking up your direct heart rate...as the weeks go by, see if your calories burned for the same intensity and time are going down with you getting in better shape...I experienced this as first too, but went with what my HRM monitor said and ignored the treadmill
  • dnish53
    dnish53 Posts: 162 Member
    HRM every time. Treadmills can vary greatly. Make sure your HRM settings are correct, but given what you have posted I would guess that they are. When your heart rate stays up there you burn more calories. As you get in better shape you will have to workout harder in order to burn the same amount of calories.
  • bluefox9er
    bluefox9er Posts: 2,917 Member
    I did a 5k run with a garmin HRM and a Polar HRM, both with accurate height/weight data. garmin said 360 calories burnt, polar said 540.

    even HRM's differ with readings...
  • philm00x
    philm00x Posts: 27
    I just ran a mile under 10 minutes (no incline, 6 mph pace for most of it) for the first time tonight and the treadmill said I burned 163 calories. When I was adding the run into my exercise log for today, based on my current weight, MFP said I would have burned 161 calories. I don't have a HRM so I couldn't say how accurate the reading is, but I'm pretty certain I burned more than it's calculating. Problem with the treadmill is that it doesn't have an input for height and weight, so it can't accurately count calories burned, but rather only estimate on an average.
  • sfxchris
    sfxchris Posts: 39
    Alright, thanks guys. It makes sense. I just saw how much people had to do to burn 450 calories in an hour and I did it in a half an hour, so I was very skeptical. But I need to stop forgetting I'm 80+ lbs overweight, haha.

    So then that means during my normal workouts (60 mins), i'm burning 900 calories. Gosh!
  • sfxchris
    sfxchris Posts: 39
    I did a 5k run with a garmin HRM and a Polar HRM, both with accurate height/weight data. garmin said 360 calories burnt, polar said 540.

    even HRM's differ with readings...
    Yikes..
  • Azdak
    Azdak Posts: 8,281 Member
    If you are not holding on to the handrails, and walking, and able to enter your weight, and on a name-brand commercial treadmill, the treadmill numbers will be the most accurate. The bigger the discrepancy between the TM and your HRM, the more it means your HRM settings are not correct (or the HRM is not that accurate).
  • Azdak
    Azdak Posts: 8,281 Member
    I just ran a mile under 10 minutes (no incline, 6 mph pace for most of it) for the first time tonight and the treadmill said I burned 163 calories. When I was adding the run into my exercise log for today, based on my current weight, MFP said I would have burned 161 calories. I don't have a HRM so I couldn't say how accurate the reading is, but I'm pretty certain I burned more than it's calculating. Problem with the treadmill is that it doesn't have an input for height and weight, so it can't accurately count calories burned, but rather only estimate on an average.

    Height is irrelevant; but there is an easy way to check this workout because of the speed. Multiply your body weight in kilograms by 10. That is your calories/hour @ 6 mph. Divide that by 6 to get cals/mile. That number should be close to the MFP number (might be off by a little because I am rounding down to get the "10" figure).
  • Azdak
    Azdak Posts: 8,281 Member
    I did a 5k run with a garmin HRM and a Polar HRM, both with accurate height/weight data. garmin said 360 calories burnt, polar said 540.

    even HRM's differ with readings...

    Depending on the Garmin model, they probably calculate calories using different methods. A GPS-based watch can use actual speed (and the more sophisticated ones can use elevation as well). The Polar has to guess what you are doing based on heart rate and it also has a larger error factor because there is such a wide range of maximum heart rates in the normal population.

    Based on your results, I would expect your Garmin underestimated the calories somewhat and the Polar overestimated calories by somewhat more.
  • sfxchris
    sfxchris Posts: 39
    If you are not holding on to the handrails, and walking, and able to enter your weight, and on a name-brand commercial treadmill, the treadmill numbers will be the most accurate. The bigger the discrepancy between the TM and your HRM, the more it means your HRM settings are not correct (or the HRM is not that accurate).

    I don't understand though, because the weight and height data registered in my HRM are accurate to the last 2 days, so it's not like I'm getting the burn results of a 300 lb person..

    And I forgot to mention, a few calculators I discovered online gave similar results to the HRM quantity, so I'm perplexed.

    It would make sense that the treadmill would be measuring the calories burned based on more standard measurements than 260 lbs and nearly 6 feet, no?
  • sfxchris
    sfxchris Posts: 39
    bump, more opinions please!
  • Azdak
    Azdak Posts: 8,281 Member
    If you are not holding on to the handrails, and walking, and able to enter your weight, and on a name-brand commercial treadmill, the treadmill numbers will be the most accurate. The bigger the discrepancy between the TM and your HRM, the more it means your HRM settings are not correct (or the HRM is not that accurate).

    I don't understand though, because the weight and height data registered in my HRM are accurate to the last 2 days, so it's not like I'm getting the burn results of a 300 lb person..

    And I forgot to mention, a few calculators I discovered online gave similar results to the HRM quantity, so I'm perplexed.

    It would make sense that the treadmill would be measuring the calories burned based on more standard measurements than 260 lbs and nearly 6 feet, no?

    The energy cost for a steady-state cardio exercise is relatively fixed. For example, the energy cost of walking 3.0 mph/5% incline is a little over 5 METs ( a MET is a measure of cardiovascular intensity). For the most part, that energy cost of 5 METs is the same, regardless of who is doing the exercise. For a fit person, 5 METs is easy to modest, for a deconditioned person, it might be somewhat hard to hard. But, it is still 5 METs.

    Calories expended per hour is a product of METs times body weight (in kg). That's it. No other information needed.

    There are energy prediction equations for simple, cardiovascular exercises such as walking, running, stairclimbing, and stationary cycling. These are long-established, validated equations.

    For a commercial treadmill, it is easy to measure speed and incline, and relatively simple to accurately estimate calories based on that workload. Enter your weight, and you are all set.

    Heart rate monitors require so much extra data because they DO NOT measure workload. Their equations were based on taking bunch of people, measuring their oxygen uptake at various heart rate intensities and then manipulating their equations to achieve a "best fit" with the measured data. I am not a math expert, so I cannot explain exactly why they need the addition factors (age, gender, height, etc). I only know that those extra factors do not make the HRM more accurate--they are there to compensate for the inherent weaknesses in estimating calories via heart rate.

    The inaccuracy of yours (and the vast majority of people who use HRMs) stems from three things:

    1. The HRM does not have your actual maximum heart rate--it is likely using a default number based on a prediction equation that can be off by 20-30 beats/min.

    2. The HRM does not know your VO2max.

    3. Not in this case, but often people use their HRMs during the wrong types of activity, such as weight training and activities of daily living.

    I have written a number of articles on this subject, if you are interested in more detail:

    http://www.myfitnesspal.com/blog/Azdak
  • sfxchris
    sfxchris Posts: 39
    If you are not holding on to the handrails, and walking, and able to enter your weight, and on a name-brand commercial treadmill, the treadmill numbers will be the most accurate. The bigger the discrepancy between the TM and your HRM, the more it means your HRM settings are not correct (or the HRM is not that accurate).

    I don't understand though, because the weight and height data registered in my HRM are accurate to the last 2 days, so it's not like I'm getting the burn results of a 300 lb person..

    And I forgot to mention, a few calculators I discovered online gave similar results to the HRM quantity, so I'm perplexed.

    It would make sense that the treadmill would be measuring the calories burned based on more standard measurements than 260 lbs and nearly 6 feet, no?

    The energy cost for a steady-state cardio exercise is relatively fixed. For example, the energy cost of walking 3.0 mph/5% incline is a little over 5 METs ( a MET is a measure of cardiovascular intensity). For the most part, that energy cost of 5 METs is the same, regardless of who is doing the exercise. For a fit person, 5 METs is easy to modest, for a deconditioned person, it might be somewhat hard to hard. But, it is still 5 METs.

    Calories expended per hour is a product of METs times body weight (in kg). That's it. No other information needed.

    There are energy prediction equations for simple, cardiovascular exercises such as walking, running, stairclimbing, and stationary cycling. These are long-established, validated equations.

    For a commercial treadmill, it is easy to measure speed and incline, and relatively simple to accurately estimate calories based on that workload. Enter your weight, and you are all set.

    Heart rate monitors require so much extra data because they DO NOT measure workload. Their equations were based on taking bunch of people, measuring their oxygen uptake at various heart rate intensities and then manipulating their equations to achieve a "best fit" with the measured data. I am not a math expert, so I cannot explain exactly why they need the addition factors (age, gender, height, etc). I only know that those extra factors do not make the HRM more accurate--they are there to compensate for the inherent weaknesses in estimating calories via heart rate.

    The inaccuracy of yours (and the vast majority of people who use HRMs) stems from three things:

    1. The HRM does not have your actual maximum heart rate--it is likely using a default number based on a prediction equation that can be off by 20-30 beats/min.

    2. The HRM does not know your VO2max.

    3. Not in this case, but often people use their HRMs during the wrong types of activity, such as weight training and activities of daily living.

    I have written a number of articles on this subject, if you are interested in more detail:

    http://www.myfitnesspal.com/blog/Azdak
    I see. I noticed you mentioned steady-state cardio, but what about interval training?
    Also, based on your explanation, that would mean my expenditure would be 590 calories per hour. Is this set in stone? Are there no other variables? I thought heart rate played an important role (fat burning/aerobic/anaerobic zones) as well as age.
  • sfxchris
    sfxchris Posts: 39
    for example, this: http://www.my-calorie-counter.com/mets_calculation.asp says:

    "To calculate the calories burned based on the METS, use this formula:

    Weight (in kg, kg = lbs/2.2) * METS = Calories Burned per hour

    This does not take into account differences in metabolism due to gender, age, or body composition which may cause results to vary."

    it seems like a basic measurement and a few variables can add or subtract from the number.

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