How accurate is the data from cardio machines?

kerrylkatriviera
kerrylkatriviera Posts: 25 Member
edited November 22 in Fitness and Exercise
One elliptical machine tells me I burn 200 calories in half an hour; another one tells me I burn 300 in half an hour. MFP says a half an hour of elliptical training is 300 calories. I don't know who to believe. I always add an extra ten minutes of stationary rowing to make sure I am burning at least 300 calories. I'm a little skeptical that a half an hour is 300 calories, because with the stationary bike I only burn 200 calories per half hour.

I always plug in my weight and age, in hopes that I get an accurate reading.

Replies

  • ladyhusker39
    ladyhusker39 Posts: 1,406 Member
    Not very
  • NorthCascades
    NorthCascades Posts: 10,968 Member
    Sadly it's going to depend on the machine, they vary wildly. The one we have reports about 1 calorie per minute, in contrast to the clearly exaggerated values above.

    If you do this often, keep a journal (MFP does this for you automatically if you use it) of how much you think you burned, how much you ate, and what the scale said. After a month or so you'll have the info you need to adjust to reality.
  • Jthanmyfitnesspal
    Jthanmyfitnesspal Posts: 3,522 Member
    Using several machines (mostly Precor and treadmill) and eating most calories back, I still lost weight at the expected rate, so I'd say the numbers are accurate enough. I also use HRM-based estimates for cycling and running and swimming is estimated by time. These have been all been good enough to keep me from gaining weight.
  • TR0berts
    TR0berts Posts: 7,739 Member
    In theory...

    If the elliptical has you input your weight, it can calculate the work you do - which is equal to the energy (Calories) you expend during your workout.

    In reality...

    It generally works for a while. But, if the machine needs maintenance, the Calorie count can end up quite off. This is especially true for treadmills (the belts stretch slightly, so the distance the machine thinks it's simulated is off), but can be true for other machines, as well.
  • sijomial
    sijomial Posts: 19,809 Member
    edited October 2017
    They are different and the estimates will vary wildly in accuracy between different machines.

    Get the brand and model details and see if you can find out how they developed their calorie burn table. Some will do lab tests with a cross section of people and estimates can be very reasonable. Others are no better than a wild guess.

    Wouldn't use the MFP elliptical guess-timate at all. There is no way MFP knows your intensity/resistance levels and is just going by your weight. An unfit couch potato who weighs the same as a super fit Olympic athlete would get the same number of calories allocated for the same duration.

    If your rower is a Concept2 their calorie counts (when adjusted for your weight) should be pretty accurate.
    Might give you a "feeling" for what a certain exercise intensity gives you as a calorie burn.
    http://www.concept2.co.uk/indoor-rowers/training/calculators/calorie-calculator
  • Azdak
    Azdak Posts: 8,281 Member
    The calorie burn numbers for most commercial machines are both accurate and inaccurate. They are accurate in that they measure your workload and can measure and average workload even with frequent changes in workload; they are accurate in that the measurements they provide will be consistent from day to day and workout to workout. What that means is that if it shows 10% more work (total calories) during a workout compared to your previous workout—you did 10% more work.

    Where they are less accurate is comparing the calorie reading to what you actually burned. While the machines accurately measure workload, they are less accurate in translating that workload into an accurate calorie count. It’s not that they are evil and manipulative—it’s just expensive and time-consuming to develop machine-specific algorithms. Most ellipticals will overestimate calories burned by 25%-30%. For some newer Life Fitness models (Disovery series), the error is probably less than 10%.
  • kerrylkatriviera
    kerrylkatriviera Posts: 25 Member
    Thanks for all of the input!
  • ninerbuff
    ninerbuff Posts: 48,988 Member
    ekeel9201 wrote: »
    The elliptical machine at my gym says I burn 500 calories in roughly 35 mins ..that's at a 15 resistance though....I think the machines are somewhat accurate. Hope that helps ya :)
    Lol, Michael Phelps burns about 16 calories a minute of hard swimming. In 35 minutes that would be 560. I TRULY DOUBT that moderately pushing through an elliptical for 35 minutes is equal to what an Olympic swimmer burns.

    Even at a 15 setting, the burn is likely right around 160-200 calories.

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  • stanmann571
    stanmann571 Posts: 5,727 Member
    ekeel9201 wrote: »
    The elliptical machine at my gym says I burn 500 calories in roughly 35 mins ..that's at a 15 resistance though....I think the machines are somewhat accurate. Hope that helps ya :)

    IF you weigh over 200 lbs and you're doing near max speed on the machine, you might get close to that number.

    Realistically, It's probably half or less.
  • leggup
    leggup Posts: 2,942 Member
    With elliptical, treadmills, and walking in the great outdoors (hilly) I find I burn about 100 calories per mile. I got this number using various machines, heart rate monitors, and eating back my calories and monitoring my weight loss.
  • NorthCascades
    NorthCascades Posts: 10,968 Member
    ninerbuff wrote: »
    ekeel9201 wrote: »
    The elliptical machine at my gym says I burn 500 calories in roughly 35 mins ..that's at a 15 resistance though....I think the machines are somewhat accurate. Hope that helps ya :)
    Lol, Michael Phelps burns about 16 calories a minute of hard swimming. In 35 minutes that would be 560. I TRULY DOUBT that moderately pushing through an elliptical for 35 minutes is equal to what an Olympic swimmer burns.

    Even at a 15 setting, the burn is likely right around 160-200 calories.

    I don't think knowing what a different person burns doing a different exercise is the best way to determine what you burned.
  • forgtmenot
    forgtmenot Posts: 860 Member
    I don’t think mine is at all but I have a pretty basic elliptical that doesn’t have to option to enter your body stats. It says I burn 100-120 calories in 30 mins of elliptical which I think is low. Mfp says 300 something. So I just pick 200 which is in the middle.
  • Jthanmyfitnesspal
    Jthanmyfitnesspal Posts: 3,522 Member
    One more time: I've compared the calorie estimate of several gym-quality machines (Precor elliptical, AMT, Lifefitness treadmill) to numbers from Fitbit, the Wahoo fitness HRM app, and other estimates, including MFP (particularly for running, swimming, and cycling).

    There is certainly disagreement at the ~15% level, so it pays to leave some exercise calories on the table. When cutting, I aimed to only eat about half back.

    When you do this for a long time you start to build up good intuition about the numbers. The most important lesson is that exercising does not give you the ability to metabolize limitless calories!
  • xvolution
    xvolution Posts: 721 Member
    Do these machines display how many watts you're outputting? If so you can get a fairly accurate calories burned count with this formula: energy (kcal) = avg power (W) X duration (hours) X 3.6.

    According to that formula you were doing 111 watts of force on the elliptical and 167 watts on the bike. The elliptical one might be accurate but I highly doubt you're doing 167 watts on that bike.
  • sijomial
    sijomial Posts: 19,809 Member
    xvolution wrote: »
    Do these machines display how many watts you're outputting? If so you can get a fairly accurate calories burned count with this formula: energy (kcal) = avg power (W) X duration (hours) X 3.6.

    According to that formula you were doing 111 watts of force on the elliptical and 167 watts on the bike. The elliptical one might be accurate but I highly doubt you're doing 167 watts on that bike.
    @xvolution
    Cycling has a well established and fairly narrow efficiency ratio (around 24%) so works well for converting power to calories. The 24% assumption is why part of the whole power to calories equation can be omitted (joules to calories).

    But you have your numbers round the wrong way - the 111 watts is for the half hour on the bike not the elliptical - 111 watts on the bike for half an hour is entirely believable I think you would agree?
    111 (watts) x 0.5 (half hour) x 3.6 = 200 calories.

    Not the same for ellipticals though as they aren't a uniform design, have different range of elevation and motion plus of course they are a weight bearing exercise unlike cycling.
  • NorthCascades
    NorthCascades Posts: 10,968 Member
    Agree with @sijomial, the 1:1 kJ to kCal only applies to cycling. On a bike, we're all spending the vast majority of our time seated, turning the pedals in a circle whose size is fixed. It basically eliminates all the variables that aren't reflected in your power output.
  • xvolution
    xvolution Posts: 721 Member
    Yeah, I misread it and thought he said 300 calories for the exercise bike.
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