Im using a Kurt Kinetic Road Machine with the Inride pod. That pod acts like a power meter. For my HR, I am using a Garmin with a chest strap. I am doing TrainerRoad workouts.
For TR, with power calculations, the calories are always much higher than what my garmin shows with HR calculations.
Here is an example.
Today I did Whiteside -1 (5x20 minutes 88% FTP 2:15 total duration). TR gave me 1103 Kj’s of work. My HR only averaged 120 bpm (41 year old male - 137 pounds) and based on that, my Garmin gave me 645 calories burned.
1103 versus 645 calories - That is a huge difference. I wonder what that means in terms of my HR being low. My cadence was 85 RPMs.
Does that sound right? My HR always runs low, but should there be that large of a discrepancy? I ask for refueling purposes. Im trying to amke sure I am getting enough calories in the day to fuel the next workout or the next day’s workout.
didn’t know what you were talking about, the inride thing, but I have an KK laying around so it got me interested. Looks like a pretty cool device, especially since the KK fluid is pretty stable across temperature. Anyway I read the DCR review of it and it looks like the calibration procedure is a pretty important with this device. Do you calibrate on every ride?
didn’t know what you were talking about, the inride thing, but I have an KK laying around so it got me interested. Looks like a pretty cool device, especially since the KK fluid is pretty stable across temperature. Anyway I read the DCR review of it and it looks like the calibration procedure is a pretty important with this device. Do you calibrate on every ride?
I calibrate it with the spindown on TR 10 minutes into the ride.
I don’t know anything about the pod you are using…but assuming that it actually estimates power and work with some accuracy, that will be the more accurate estimate of calories burned. Calories burned is proportional to work performed which is watts integrated over time, multiplied by a fudge factor.
Garmin with just heart rate to go by has no real basis for the calorie estimate it gives you. Garmin would need to know something about your work rate per bpm. So, it is likely to be wildly inaccurate. Maybe better than nothing, but not by much.
Two guys riding a trainer, both have a heart rate of 150 bpm: one is producing 150 watts, the other is producing 300 watts. Do you think they are burning the same calories?
Im using a Kurt Kinetic Road Machine with the Inride pod. That pod acts like a power meter. For my HR, I am using a Garmin with a chest strap. I am doing TrainerRoad workouts.
For TR, with power calculations, the calories are always much higher than what my garmin shows with HR calculations.
Here is an example.
Today I did Whiteside -1 (5x20 minutes 88% FTP 2:15 total duration). TR gave me 1103 Kj’s of work. My HR only averaged 120 bpm (41 year old male - 137 pounds) and based on that, my Garmin gave me 645 calories burned.
1103 versus 645 calories - That is a huge difference. I wonder what that means in terms of my HR being low. My cadence was 85 RPMs.
Does that sound right? My HR always runs low, but should there be that large of a discrepancy? I ask for refueling purposes. Im trying to amke sure I am getting enough calories in the day to fuel the next workout or the next day’s workout.
Do you have an estimation of your FTP? By strict calculation 1106 calories burned over 2.25 hours works out to an average power of 136 watts. If you do the same calculation with 645 calories its 80 watts. I am guessing you didn’t average 80 watts for 2:15 on a trainer (judging simply as a 41 year old, 137lb male). Depending on your FTP though, 136 still seems pretty low considering you had 5x20 minutes at 88% in there.
That said, I never really trust those estimated power things as they are extremely dependent on things like tire pressure and rolling resistance of the tire, etc. But I am guessing the higher calorie number is at least a little more likely just from a perspective of how much time you spent on the bike and what your workout was.
Power is always going to give a much better reading on calories than heart rate for the simple reason that power is measuring the actual work being done and there is a direct relationship between a certain amount of work over time (i.e. watts) and the number of calories it takes to generate that amount of work. You still have some individual variations but that plays out over a relatively small range.
On the other hand, tying calories to heart rate is pretty much just a wild ass guess. Not only is HR vs calories wildly different between different athletes, it is variable in the same athlete over different times and conditions.
That being said, there is the issue of whether your Inride is giving you an accurate estimate of your power . . .
If I understand correctly, you’ve got two figures for calories expended. One based solely on HR and duration (Garmin) and one based on power output (TR), and you are wondering why the big difference and which to believe?
The Garmin is a very rough estimate. It’s not doing any direct measurement of energy usage, but simply applying an algorithm they reckon gives a reasonable estimate given the very limited available info. This will presumably be very dependent on your inputs such as your min/max HR and zones ranges.
A measurement of power output (indirect in this case but should still be fairly accurate), provides TR with far more useful information. It can directly calculate energy that went into output on the bike. There will be an additional energy cost that never makes it to the pedals, that needs to be replenished by the athlete too.
Regardless, I don’t think it’s reasonable to expect the figures to match when they’re being fed different and incomplete data. Secondly, and more importantly from a nutrition point of view - just watch your weight. If it goes up you’re over-fuelling. If it’s going down, you’re under-fuelling. I think you’re over complicating things.
On a separate note. I used a Kurt Kinetic with Zwift for the last two years. I did not have a power meter and simply used virtual power. I was careful to keep things consistent in terms of the tyre, tyre pressure, and roller clamping pressure. The Zwift virtual power figures seemed very consistent but I had no way to know if they were accurate. I always used a 23mm Felt TTR tyre, with the same butyl tube, inflated to 100psi and turned the roller compression knob exactly 3 full turns from first contact. I recently got a power meter (Power2max NGeco) and for the first few trainer rides I didn’t pair the power meter with Zwift. I left Zwift operating on virtual power based on wheel speed. I was extremely surprised to find that after a ~10% error during the first 10mins of a session (presumably while the gel warmed a little), the virtual power and PM figures were extremely consistent. By which I mean, the averages for splits in sessions were always within 1-2% except during when I was doing short (1min) high intensity efforts with similar short rests in between (probably due to the hard accelerations and limitations of virtual power in that respect). I was pleasantly surprised, switched to PM on Zwift and nothing else changed (except it’s more responsive when I sprint!).
Two guys riding a trainer, both have a heart rate of 150 bpm: one is producing 150 watts, the other is producing 300 watts. Do you think they are burning the same calories?
^this
When’s the last time you checked your FTP?
I used to use the InRide pod before upgrading to P1 pedals and in my experience, the InRide was pretty darn accurate. DCRainmaker’s review on the InRide pod said essentially the same thing.
Do you have an estimation of your FTP? By strict calculation 1106 calories burned over 2.25 hours works out to an average power of 136 watts. If you do the same calculation with 645 calories its 80 watts. I am guessing you didn’t average 80 watts for 2:15 on a trainer (judging simply as a 41 year old, 137lb male). Depending on your FTP though, 136 still seems pretty low considering you had 5x20 minutes at 88% in there.
That said, I never really trust those estimated power things as they are extremely dependent on things like tire pressure and rolling resistance of the tire, etc. But I am guessing the higher calorie number is at least a little more likely just from a perspective of how much time you spent on the bike and what your workout was.
My FTP is only 175 watts. That is what it tested at 12 weeks ago on TR using the KK trainer. I always use the same tire pressure and everything.
For the 5x20 minutes, those were done at 154 watts each.
I have been riding TR with the KK machine for 12 weeks, and setup everything exactly. I am on it so much that I can feel the difference in 154 watts and 149 watts even.
I just finished the 12 week High Volume Full IM Training Plan and did every ride without missing one on TR with the KK. That’s about 78.5 hours so far.
Power is always going to give a much better reading on calories than heart rate for the simple reason that power is measuring the actual work being done and there is a direct relationship between a certain amount of work over time (i.e. watts) and the number of calories it takes to generate that amount of work. You still have some individual variations but that plays out over a relatively small range.
On the other hand, tying calories to heart rate is pretty much just a wild ass guess. Not only is HR vs calories wildly different between different athletes, it is variable in the same athlete over different times and conditions.
That being said, there is the issue of whether your Inride is giving you an accurate estimate of your power . . .
So a 150 lb vs a 225 lb person would burn approx the same calories for the same power output?
Asking for real as I’m thinking about getting the power tap chain rings
For the 5x20 minutes, those were done at 154 watts each.
I have been riding TR with the KK machine for 12 weeks, and setup everything exactly. I am on it so much that I can feel the difference in 154 watts and 149 watts even.
I just finished the 12 week High Volume Full IM Training Plan and did every ride without missing one on TR with the KK.
From pretty much everyone I know who has used the TR and KK algorithm, it is pretty darn accurate - all assuming you keep things consistent and perform the roll-down correctly and all that.
So…I would for sure rely on the calories burned calculation from TR opposed to the Garmin calculation derived from HR.
As someone else pointed out, you can have two people with the same average HR, but have vastly different average power. It’s the work that counts (Power).
Power is always going to give a much better reading on calories than heart rate for the simple reason that power is measuring the actual work being done //
Why do you think this?? Lets say Bjorn who can hold 465 watts for nearly an hour does 300 watts for an hour, and some schlub who can barley hold those 300 watts for an hour are compared, what do you think the calorie burn of each would look like???
Now if you took HR of each guy and they were both working at 80% of their own max for an hour, what do you think that calorie burn would look like??
I think the HR burn would be much closer for comparison sake than the power one, but I can be convinced if you have a better argument for these two people??
Power is always going to give a much better reading on calories than heart rate for the simple reason that power is measuring the actual work being done and there is a direct relationship between a certain amount of work over time (i.e. watts) and the number of calories it takes to generate that amount of work. You still have some individual variations but that plays out over a relatively small range.
On the other hand, tying calories to heart rate is pretty much just a wild ass guess. Not only is HR vs calories wildly different between different athletes, it is variable in the same athlete over different times and conditions.
That being said, there is the issue of whether your Inride is giving you an accurate estimate of your power . . .
So a 150 lb vs a 225 lb person would burn approx the same calories for the same power output?
Asking for real as I’m thinking about getting the power tap chain rings
Yes. 200 watts is 200 watts no matter how heavy you are. And 200 watts is going to be the same calorie expenditure no matter how heavy you are. The difference is that the 150lb person is going to go much faster, especially on a hilly course, on those 200 watts than the 225lb person will.
Power is always going to give a much better reading on calories than heart rate for the simple reason that power is measuring the actual work being done //
Why do you think this?? Lets say Bjorn who can hold 465 watts for nearly an hour does 300 watts for an hour, and some schlub who can barley hold those 300 watts for an hour are compared, what do you think the calorie burn of each would look like???
Now if you took HR of each guy and they were both working at 80% of their own max for an hour, what do you think that calorie burn would look like??
I think the HR burn would be much closer for comparison sake than the power one, but I can be convinced if you have a better argument for these two people??
Their calorie burn would be the same. A watt is a watt. A kilo-joule is a kilo-joule. Just because one person nearly killed himself to make it happen and the other didn’t doesn’t mean the actual physical output was different.
The good thing about a Joule is its a unit of energy showing how much work it took to produce one watt per second. In other words, the watt of Bjorn is the same as the watt of Joe Blow (not watts, but watt). Bjorn can produce many more watts per hour, and Joe Blow cannot
Physics and math. Watts are a measure of power and kilojoules are a measure of energy and the energy needed to create a certain amount of power is a fixed formula whether it is for an F1 car, a Space X rocket or a human on a bike. Converting kilojoules to calories has a bit of variation but the error range it is pretty narrow. So, it is very easy and pretty consistent to convert watts to calories for humans on bikes.
Heart Rate on the other hand is a measure of how many times a muscle contracts. Hearts and circulatory systems vary greatly and there is huge variability among humans as to how many BPM equals a certain amount of power output. Getting calories from HR is an extrapolation from something (HR) that is not directly tied to power output using a generic formula not tied to an individual’s circulatory efficiency. Not only that, within the same human the variability between BPM per X watts has huge variations both over long periods of time (e.g. as fitness and the efficiency of the circulatory system changes) and short term as fatigue changes during a ride. 150 bpm is not necessarily the same as it was 3 years ago or even 45 miles ago and it is certainly not the same for the guy riding next to you. On the other hand, a watt is a watt and it is always going to equate to the same number of kilojoules and kilojoules to calories does not change much over time for an individual or rider to rider.
It is not impossible to get good estimates of calorie output using heart rate but it is also possible to be way off and not the same over time for an individual. A power meter is always going to give you better calorie numbers and it is never going to be way off since you are using an actual measure of work to calculate the actual energy needed to produce that work.