Question about the Elemnt
06-06-18, 03:37 PM
#26
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Bikes: 2015 Cannondale Synapse Carbon 105; 2015 Felt V100
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Power and calories
There's been some other threads about calorie calculations using a power meter.
There have been many tests / reviews with 2, 3, or 4 different power meters on the same bike. They usually match up very well, often within 5% of each other. So I think the power meters are quite accurate. Different software rounds and smooths the data with different formulas, so the totals for the ride are usually a little different.
Lab tests measuring CO2 output, etc, can calculate calories burned quite accurately.
From this article "convert watts to calories"
The efficiency of calories to useful work is around 20% to 25%. The other 75% to 80% is wasted heat!
One joule is defined as one watt per second. One (kilo)calorie is 4.18 kilojoules.
Then, since the conversion to useful work is about 1/4 (25%), calories burned are pretty close to kilojoules. No math needed. This is a lot more accurate than estimating using heart rate, or road speed & elevation.
There's been some other threads about calorie calculations using a power meter.
There have been many tests / reviews with 2, 3, or 4 different power meters on the same bike. They usually match up very well, often within 5% of each other. So I think the power meters are quite accurate. Different software rounds and smooths the data with different formulas, so the totals for the ride are usually a little different.
Lab tests measuring CO2 output, etc, can calculate calories burned quite accurately.
From this article "convert watts to calories"
The efficiency of calories to useful work is around 20% to 25%. The other 75% to 80% is wasted heat!
One joule is defined as one watt per second. One (kilo)calorie is 4.18 kilojoules.
Then, since the conversion to useful work is about 1/4 (25%), calories burned are pretty close to kilojoules. No math needed. This is a lot more accurate than estimating using heart rate, or road speed & elevation.
Thank you.
06-16-18, 12:04 PM
#27
Senior Member
I have the Elemnt, an Edge 1000, and I used Cyclemeter for a long time. I was also very interested in getting an accurate calorie burn number and the fact that there was such serious discrepancies between numbers drove me nuts.
I found that the number that Strava gave me was the most conservative. Cyclemeter was all over the map and tended to be about 2X high from I thought it ought to be. Garmin was also high but got better with both adding a HRM and a power meter - same for the Elemnt. I also tried this with my Apple Watch since Apple did a lot of work on active calorie burn for their workouts app.
I think there are a couple of things in play in all of this. First, is that some of the apps like Cyclemeter appear to use total calories instead of active calories (active calories are the burn above and beyond your normal burn that comes directly from the exercise). That pushes it up higher than it should be by a considerable amount.
All of the computers were too high without any of the sensors, just using speed and cadence. In other words, adding each sensor helped get to better agreement between all of the methods (Garmin, Element, Strava). This does not include Cyclemeter, I quit using that because it was the outlier.
So I would say that there is better agreement with Strava when a power meter AND a HRM are used. Adding each one individually seemed to give me a better number. Adding them both seemed to get to really pretty good agreement. All of the methods will get within about 70-100 calories for a 90 minute ride (700+ total active calories). At this point, it's differences in algorithms, auto pause etc.... I think.
I did not notice a 2X or even a large deviation from Strava with the Elemnt nor would I say that Garmin is anywhere near the gold standard. I decided, just for purposes of being conservative, to use Strava as the benchmark simply because I needed to pick something and their number was the most conservative. I actually found the Elemnt to be pretty good - to the point where I switched from the Edge 1000 to the Elemnt. I think the Elemnt did a better job recording and displaying information and was as accurate if not more so than the Edge 1000.
Anyway, I hope that helps. Calorie burn going back a couple of years was all over the map. I think, in large part, due to Apple's research into this and the large number of Apple Watches out in the wild measuring workouts, it has forced everyone to be somewhat more accurate and in better agreement. I think there still is convergence going on in this particular parameter amongst manufacturers.
J.
I found that the number that Strava gave me was the most conservative. Cyclemeter was all over the map and tended to be about 2X high from I thought it ought to be. Garmin was also high but got better with both adding a HRM and a power meter - same for the Elemnt. I also tried this with my Apple Watch since Apple did a lot of work on active calorie burn for their workouts app.
I think there are a couple of things in play in all of this. First, is that some of the apps like Cyclemeter appear to use total calories instead of active calories (active calories are the burn above and beyond your normal burn that comes directly from the exercise). That pushes it up higher than it should be by a considerable amount.
All of the computers were too high without any of the sensors, just using speed and cadence. In other words, adding each sensor helped get to better agreement between all of the methods (Garmin, Element, Strava). This does not include Cyclemeter, I quit using that because it was the outlier.
So I would say that there is better agreement with Strava when a power meter AND a HRM are used. Adding each one individually seemed to give me a better number. Adding them both seemed to get to really pretty good agreement. All of the methods will get within about 70-100 calories for a 90 minute ride (700+ total active calories). At this point, it's differences in algorithms, auto pause etc.... I think.
I did not notice a 2X or even a large deviation from Strava with the Elemnt nor would I say that Garmin is anywhere near the gold standard. I decided, just for purposes of being conservative, to use Strava as the benchmark simply because I needed to pick something and their number was the most conservative. I actually found the Elemnt to be pretty good - to the point where I switched from the Edge 1000 to the Elemnt. I think the Elemnt did a better job recording and displaying information and was as accurate if not more so than the Edge 1000.
Anyway, I hope that helps. Calorie burn going back a couple of years was all over the map. I think, in large part, due to Apple's research into this and the large number of Apple Watches out in the wild measuring workouts, it has forced everyone to be somewhat more accurate and in better agreement. I think there still is convergence going on in this particular parameter amongst manufacturers.
J.
