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Joule vs. Garmin calorie value
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 2016-05-04 7:19 PM |
Member 1487    Scottsdale, AZ |  Subject: Joule vs. Garmin calorie valueHey all! Not trying to nit pick the accuracy of calories burned during exercise (because I know that is simplifying things), but I've been trying to track my diet and training in the effort to lean out a little. Thought one of the power people on this site might have some insight. I teach cycle classes indoors 2x/week on Cycleops bikes with power meters, with the joule computer. Lately I've been wearing my Garmin 910xt to collect HR data, but the Joule displays the HR as well. For a normal class, the joule says I burn anywhere from 550-650 cals for a 55 min class (yes, we work HARD), but my Garmin has been displaying significantly less. I have all the metrics set up for the Joule correctly and the HR it collects matches what displays on the Garmin. Yesterdays class for example, the joule said I burned 625 calories and my Garmin said 427. I would understand if there was a slight difference, but 200 calories? Just wondering what one is more accurate - or just take an average :-). Again, I'm trying not to get caught up on a number, but trying to keep an eye on nutrition and training output and I'd like to have some approx correct values. 200 seems like a BIG difference between units. FTR - I've checked all the settings on both and all are up to date and correct. The bikes are calibrated regularly. Thanks for any insight. |
| 2016-05-04 7:33 PM in reply to: runspingirl |
Extreme Veteran 5722  | Subject: RE: Joule vs. Garmin calorie value |
| 2016-05-04 7:35 PM in reply to: runspingirl |
| Subject: RE: Joule vs. Garmin calorie value I'm not smart enough to know the exact science or math, but I know I've read before that calories burned from a power meter will be very close to accurate. It should account for not only the work you are putting into the pedals, but energy lost to heat and some other scientific stuff like that. |
| 2016-05-04 7:48 PM in reply to: Jason N |
Extreme Veteran 5722 | Subject: RE: Joule vs. Garmin calorie value Originally posted by Jason N I'm not smart enough to know the exact science or math, but I know I've read before that calories burned from a power meter will be very close to accurate. It should account for not only the work you are putting into the pedals, but energy lost to heat and some other scientific stuff like that. that is correct. You need to know average power and duration to do that calculation. Power * duration (in sec) / 1000 will give you a number pretty close to the calories burned taking into account an "average" efficiency. |
| 2016-05-04 8:01 PM in reply to: 0 |
| Member 1487 Scottsdale, AZ | Subject: RE: Joule vs. Garmin calorie value Originally posted by marcag Do you know you average power and duration of the workout ? I don't from yesterday since my Garmin only records HR, but I will look tomorrow and get the info from the Joule, along with collect the data from tomorrows workout and have that to compare. I also teach on Wattbikes once a week (which supposedly have the most accurate power meter) and a couple weeks ago, the calorie output was over 650 while my Garmin said 470. Thanks! I appreciate the response! Edited by runspingirl 2016-05-04 8:12 PM |
| 2016-05-05 7:08 AM in reply to: runspingirl |
Member 1748 Exton, PA | Subject: RE: Joule vs. Garmin calorie value Calories is a measure on energy, If you use a power meter it will be very close to accurate. All other methods are educated guesses based on an algorithm the manufacturer came up with. Who's is most accurate???? |
| 2016-05-05 6:27 PM in reply to: marcag |
| Member 1487 Scottsdale, AZ | Subject: RE: Joule vs. Garmin calorie value Ok, got the data from this mornings class… 59:11 total time (including cool down) 176 avg watts so if I did the calculation I get 625.25 calories Joule said 632 KJ, so that is pretty close Garmin said 395 calories That's a huge difference IMO I checked the Garmin periodically and the HR matched what the Joule was displaying too. So obviously there is something wrong with the Garmin. I checked all the settings and everything seems fine. May research that a little further. Not like it's that important, but if there is something off I'd like to fix it. |
| 2016-05-06 5:26 PM in reply to: runspingirl |
| Member 1487 Scottsdale, AZ | Subject: RE: Joule vs. Garmin calorie value Class today on the Wattbike - which again, are supposed to be extremely accurate. Took it a little easier since I have a race this weekend. 153 avg Watts for 50 min. Wattbike said I burned over 600 calories. Doing the calculation, it would only be 460. I love how people RAVE about HOW MANY CALORIES THEY BURNED on machines, but in reality, you really do need to look at the data! |
| 2016-05-06 6:36 PM in reply to: runspingirl |
Extreme Veteran 5722 | Subject: RE: Joule vs. Garmin calorie value Originally posted by runspingirl Class today on the Wattbike - which again, are supposed to be extremely accurate. Took it a little easier since I have a race this weekend. 153 avg Watts for 50 min. Wattbike said I burned over 600 calories. Doing the calculation, it would only be 460. I love how people RAVE about HOW MANY CALORIES THEY BURNED on machines, but in reality, you really do need to look at the data! When you use the power * time you are calculating the energy produced The amount of calories burned varies with the efficiency of the rider. Maybe Wattbike is assuming low efficiency. What did Garmin say ? |
| 2016-05-06 9:20 PM in reply to: marcag |
| Member 1487 Scottsdale, AZ | Subject: RE: Joule vs. Garmin calorie value Originally posted by marcag Originally posted by runspingirl Class today on the Wattbike - which again, are supposed to be extremely accurate. Took it a little easier since I have a race this weekend. 153 avg Watts for 50 min. Wattbike said I burned over 600 calories. Doing the calculation, it would only be 460. I love how people RAVE about HOW MANY CALORIES THEY BURNED on machines, but in reality, you really do need to look at the data! When you use the power * time you are calculating the energy produced The amount of calories burned varies with the efficiency of the rider. Maybe Wattbike is assuming low efficiency. What did Garmin say ? Garmin said 335 cal |
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