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310xt and calorie usage -- seriously?

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  • 310xt and calorie usage -- seriously?

    I'm having a lot of trouble believing that I'm truly using as few calories as the Garmin claims I do. My users settings are as follows:

    Gender: Female
    Age: 44
    Weight: 130 lbs
    Height: 65"
    Activity Class: 9
    Lifetime Athlete: No*
    Resting heart rate: 45
    Maximum heart rate: 208

    This morning I went out on a 8.7 run, running the first 4 miles at 75% HRMax. The next 4.7 miles were at tempo effort, between 88-90% HRMax.

    Grand total calories used? 475

    This is consistent with what I've gotten for other hard workouts, and it's not that much more in terms of relative calorie usage than I get with easy workouts (runs at 60-65% HRMax). Am I really only using less than 55 calories a mile when running hard? I find this hard to believe.

    As an experiment I plan to plug in wildly different user profile settings before I do a hard 20 miler this Sunday, just to see if I get a very different calculation for calorie usage. But it would be helpful to know if these calculations truly reflect physiological reality.

    *Although it should probably be set to Yes, since my resting pulse is well below 60 and I've been training hard for 3+ years. But I can't reconcile that with the word "lifetime."

  • #2
    I agree

    The HR based calories for the 310XT seem VERY low. Compared to my old Polar HRM, its been somewhere between 25% and 30% lower. A 45 min run used to log 625-650 calories but the 310XT is in the upper 400's.

    My data:
    Gender: male
    Age: 25
    Weight: 150 lbs
    Height: 72"
    Activity Class: 9
    Lifetime Athlete: yes
    Resting heart rate: 45
    Maximum heart rate: 195

    Comment


    • #3
      I think in general the 310XT calorie count is lower because the 310XT uses a more accurate heartbeat based algorithm for calculation than previous Garmin (& probably Polar) products. Here is a link to a Firstbeat Technologies White Paper on this subject.

      http://www.firstbeattechnologies.com...ure_Estimation

      I can imagine most people getting upset because they would prefer to be burning more calories rather than less, unfortunately if the science is correct then that is the way it is.

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      • #4
        Another option is to get a New Leaf test and have the 310 calculate based on your specific make-up.

        April
        http://www.enduranceriderblog.com

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        • #5
          FWIW, in cycling mode the calories agree pretty closely with the KJoules figure from my powertap, so I tend to think the 310XT calorie calculation is pretty accurate.

          Comment


          • #6
            Originally posted by R.MCLACHLAN View Post
            I can imagine most people getting upset because they would prefer to be burning more calories rather than less.
            Not necessarily. I would rather err on the low side, especially if I'm on a calorie restrictive diet to lose weight. If you allow yourself to ingest more calories because of erroneous data from your device then you're likely to not lose weight according to your schedule, maybe even gain.
            Phil M.
            myConnect | StravaHeatmap | Instagram
            F201 F205 F305 FR50 310XT 920XT
            nĂ¼vi 67LMT

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            • #7
              No, the calorie counts, are wildly inacurate. As noted above, there is no way she is only burning 55 calories per mile on a hard run. Chances are it is well over 100. I see the same discrepancy as compared to a VO2 max test I had done where they calculate calorie burn rate based on oxygen uptake levels and corilated to HR zones. The FR310 is definitely way under estimating calorie burn, both on the bike and the run. Polar is actually quite accurate all VO2 max testing I have done since it bases the calorie count completely on the HR and the user profile including age, weight, VO2 Max, sex. I thought Garmin had finally done similar stuff with the FR310.

              Comment


              • #8
                Originally posted by R.MCLACHLAN View Post
                I can imagine most people getting upset because they would prefer to be burning more calories rather than less, unfortunately if the science is correct then that is the way it is.
                Aye, there's the rub: All I want to know is if the numbers are correct. I'll happily accept them if they are.

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                • #9
                  Originally posted by JTHRELKELD View Post
                  Aye, there's the rub: All I want to know is if the numbers are correct. I'll happily accept them if they are.
                  Well all I can say is there does seem to be some science and analysis in the Firtsbeat White paper. BTW I am assuming that users are using a HRM - if not then the 310XT improved calorie count method is invalid.

                  Comment


                  • #10
                    Interesting discussion. It looks that Garmin is using some pre-defined VO2max values for the activity class you set in the HRM. Suunto uses the same algorithm, but it also lets you input your VO2max as METs which is then used to calculate the caloric burn. Garmin does not have this value therefore I assume they use pre-defined VO2max values with each activity class or use the simpler algorithm that is in lower end model Suunto units.

                    In general Polar units give highest caloric burn followed by Suunto and the new Garmin 310 seems to underestimate the caloric burn quite a bit. Both Polar and Suunto use the VO2max values for caloric burn calculation. Suunto recently published new version of firmware for their units that corrects the caloric burn. I wonder whether this fix from FirstBeat was already implemented in the 310 firmware or will be in the future.

                    All in all these caloric burn figures from HRMs are estimates and as some recently published studies shown they can be up to 15% off the real burning. So take them with grain of salt. If you are running you are burning anywhere from 80 to 130 kcal per mile (yeah wide range depending on intensity of the run, body weight, VO2max, ...). I'm just happy we do not run with the tube sticking out of our mouth connected to the watch to assess the exact caloric expenditure ;-).

                    Jan

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                    • #11
                      The ascent software gets the raw data from the 310xt. It also takes HR into the consideration for calorie computation. It usually shows about 15 to 20% higher than the 310xt. I'm not sure which one is more accurate. Probably neither...
                      I noticed that during my interval trainings (Usually 45 minutes) I usually burn only 550 cal. But that is very intense almost all in zone 4-5...

                      Comment


                      • #12
                        Originally posted by JTHRELKELD View Post
                        I'm having a lot of trouble believing that I'm truly using as few calories as the Garmin claims I do. My users settings are as follows:

                        Gender: Female
                        Age: 44
                        Weight: 130 lbs
                        Height: 65"
                        Activity Class: 9
                        Lifetime Athlete: No*
                        Resting heart rate: 45
                        Maximum heart rate: 208

                        This morning I went out on a 8.7 run, running the first 4 miles at 75% HRMax. The next 4.7 miles were at tempo effort, between 88-90% HRMax.

                        Grand total calories used? 475

                        This is consistent with what I've gotten for other hard workouts, and it's not that much more in terms of relative calorie usage than I get with easy workouts (runs at 60-65% HRMax). Am I really only using less than 55 calories a mile when running hard? I find this hard to believe.

                        As an experiment I plan to plug in wildly different user profile settings before I do a hard 20 miler this Sunday, just to see if I get a very different calculation for calorie usage. But it would be helpful to know if these calculations truly reflect physiological reality.

                        *Although it should probably be set to Yes, since my resting pulse is well below 60 and I've been training hard for 3+ years. But I can't reconcile that with the word "lifetime."
                        Curious how you arrived at the max HR of 208? Not saying that is incorrect, but certainly an outlier for your age which could have something to do with the 310 giving very low calorie readings. Would have to believe calorie burn rates to based upon typical data points in cases where proper individual testing is not involved.
                        Anthony

                        My GC Digest

                        Comment


                        • #13
                          310xt calorie calc.

                          I've been using the 310xt for about a month. my riding partner uses a 405cx. Both advertise that they use an advanced calorie caluclation. We both have input same fitness level 8. 405cx does not have "lifetime fitness" setting. I'm 59, he's 43. On a two hour ride my average HR is about 135, his about 140. My indicated calorie burn is about half his. One, or both, of the units is seriously in error. Many comments questioning 310xt, hope Garmin looks at this.

                          Comment


                          • #14
                            Originally posted by KANSAIBEN View Post
                            Curious how you arrived at the max HR of 208? Not saying that is incorrect, but certainly an outlier for your age which could have something to do with the 310 giving very low calorie readings. Would have to believe calorie burn rates to based upon typical data points in cases where proper individual testing is not involved.
                            That's an interesting theory.

                            208 is the highest an HRM ever hit for me -- I tore through the last quarter mile of a 5K a few years ago. Previous readings for fast, hard races had been in the low 200 range, so I tend to believe that's my max.

                            Today was the real kicker: Garmin had me burning 60 cals for a 9:30 mile, then 50 for an 8:30 subsequent mile. I'm going to ignore the caloric data until Garmin fixes this.

                            Now. Can we hear from someone at Garmin?

                            Comment


                            • #15
                              Originally posted by JRMITCH View Post
                              I've been using the 310xt for about a month. my riding partner uses a 405cx. Both advertise that they use an advanced calorie caluclation. We both have input same fitness level 8. 405cx does not have "lifetime fitness" setting. I'm 59, he's 43. On a two hour ride my average HR is about 135, his about 140. My indicated calorie burn is about half his. One, or both, of the units is seriously in error. Many comments questioning 310xt, hope Garmin looks at this.
                              Are you the same weight? Remember calories are about energy consumption - it requires more energy to move a greater weight.

                              I must admit I do not fully understand calorie consumption as from the basic laws of physics it takes the same energy to move a mass a fixed distance regardless of the velocity, only the time taken changes. This does not seem to be the case here as more energy seems to be consumed running a fixed distance than walking the same distance - perhaps body heat produced accounts for the difference?
                              Last edited by R.MCLACHLAN; 09-04-2009, 04:43 PM.

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