Concept2 Forum

Hi,

It seems after i updated the firmware on my concept 2 pm5 it dosent count the calories right anymore.
calories per hhour seems right but total dosent macth, any one of you have the same issue? and maybe a solution to fix it?
https://imgur.com/a/6m7pEYx

I couldn't see your picture without accepting cookies....but stuff you should perhaps be aware of if not already.

The erg and PM5 is a very accurate measure of the work that you are doing. This is expressed in either pace or watts. There is also the potential to display calories, but this is at best a very rough estimate and makes all sorts of assumptions about the individual on the erg which cannot be accurate given the differences in sex/size/metabolism/etc.

If its burnt calories that motivates you then its fine to see relative burn in different sessions, but it would be a mistake to think that it has ever been an accurate calorie counter.

https://postimg.cc/CBD8Wj2N hope this link is better.
I am just wondering why it changed from being somewhat accurate to be way off.
yesterday i did a 1 hour row.

calories per hour is 884
and it says i burnt 2666 calories

on 10k row its tells me 6000 calories
its just weird the calories per hour hasent changed.
but calories burnt is way off now.

hope it make sense

It's clearly wrong. Not sure if it's "uninstall ergdata, reinstall" or if it's "reset pm5" or "log had a bad day"

Best is to email concept2 at info@concept2.com give snapshots, firmware version, ergdata version, say if it still happens or if it was only once.

Aside: your PM5 has a history function that will show you the calories that the PM5 thinks you burned on that workout. You can see if it's the same as the log or different.

Ignoring the fact that something is clearly wrong - unless you are the "perfect" human that C2 modelled the calorie calc on, it's going to be off anyway, as it is a generic calc based on some quite big assumptions. (essentially only any use for rough ballpark figures imo - 1hr at x pace is more work than 45mins at Y pace sorta thing).

p_b82 wrote: ↑

July 5th, 2025, 6:31 am

Ignoring the fact that something is clearly wrong - unless you are the "perfect" human that C2 modelled the calorie calc on, it's going to be off anyway, as it is a generic calc based on some quite big assumptions. (essentially only any use for rough ballpark figures imo - 1hr at x pace is more work than 45mins at Y pace sorta thing).

Well, the C2 is an erg so it knows how many calories you're delivering to the flywheel, regardless of pace, drag factor, etc. What it doesn't know is your metabolic efficiency or, for that matter, mechanical efficiency.

Personally, I'd like to see a cumulative measure of external work done, but C2 has decided not to provide that. e.g. kwatt-seconds = Kjoules. Easy enough to calculate from power and duration, but still I'd like to see it.

This calorie stuff is the most useless metric on any erg.
Same applies to the calories of food. It's a heat unit and does not tell anything about how efficient the body produces the power for the erg nor metabolizes the macro content of food.

Apart from this: yes, the logbook overall line gives a completely wrong calorie value. In this example it seems to report factor 3 of the actual value.

The calories are all over the place. Best to just ignore it. My take is the harder the effort the more accurate it is. This bears out over many rows. I row with a H10 and take that reading.

Example of two of my sessions recently.
10,000 metres. 45:05. PM5 580, H10 574.
6,000 metres. 30:06. PM5 324, H10 194.

Sakly wrote: ↑

July 5th, 2025, 9:48 am

This calorie stuff is the most useless metric on any erg.

perhaps, but if watts and splits are OK then Calories are OK.

There's a simple transform on watts to get Calories. **

Any insight you get from improving your watts can also be obtained by looking at changes in reported calories.

===============

** if anyone cares, this is the transform: cal/hr = 300 + (4 x watts/1.1639 cal/watt-hr). The 4 is C2's view on erg energy efficiency (burn 4 units to get 1 output unit), the 1.1639 is to coerce units, the 300 is a weight dependent fudge factor for base metabolism and unmeasured output like moving your body mass up and down the erg track.

The formula follows a study by Bassett et al, Ball State University, 1983, according to C2. https://concept2help.zendesk.com/hc/en- ... s-formulas

Tsnor wrote: ↑

July 5th, 2025, 4:13 pm

Sakly wrote: ↑

July 5th, 2025, 9:48 am

This calorie stuff is the most useless metric on any erg.

perhaps, but if watts and splits are OK then Calories are OK.

There's a simple transform on watts to get Calories.

And that's the fallacy.
Watts and splits show you exactly what power is put into the machine. A physical measurement.
Calories cannot be measured during the workout (or after, before or any time). The body even does not "burn calories" at all, but that's probably a side topic here.
Watts = measured.
Calories = value out of nowhere.

Sakly wrote: ↑

July 5th, 2025, 5:25 pm

Tsnor wrote: ↑

July 5th, 2025, 4:13 pm

Sakly wrote: ↑

July 5th, 2025, 9:48 am

This calorie stuff is the most useless metric on any erg.

perhaps, but if watts and splits are OK then Calories are OK.

There's a simple transform on watts to get Calories.

And that's the fallacy.
Watts and splits show you exactly what power is put into the machine. A physical measurement.
Calories cannot be measured during the workout (or after, before or any time). The body even does not "burn calories" at all, but that's probably a side topic here.
Watts = measured.
Calories = value out of nowhere.

Well, you're sorta both right. C2 Calorie calculation gives you 150 Cal/Hr just for passing Go. If you subtract 150 Cal/Hr, you get an actual measure of (external) work done. Not in Calories, but a measure that is proportional to Calories.

gvcormac wrote: ↑

July 5th, 2025, 5:33 pm

Sakly wrote: ↑

July 5th, 2025, 5:25 pm

Tsnor wrote: ↑

July 5th, 2025, 4:13 pm

perhaps, but if watts and splits are OK then Calories are OK.

There's a simple transform on watts to get Calories.

And that's the fallacy.
Watts and splits show you exactly what power is put into the machine. A physical measurement.
Calories cannot be measured during the workout (or after, before or any time). The body even does not "burn calories" at all, but that's probably a side topic here.
Watts = measured.
Calories = value out of nowhere.

Well, you're sorta both right. C2 Calorie calculation gives you 150 Cal/Hr just for passing Go. If you subtract 150 Cal/Hr, you get an actual measure of (external) work done. Not in Calories, but a measure that is proportional to Calories.

Sure, you can calculate an amount of calories (= heat unit), which is equivalent to the power you put into the machine. But for what reason you want to do that? This is not helpful for anything.
As soon as the word "calories" comes up, one thinks of calories burned by the body, but this is not happening.

Sakly wrote: ↑

July 6th, 2025, 2:00 am

Sure, you can calculate an amount of calories (= heat unit), which is equivalent to the power you put into the machine. But for what reason you want to do that? This is not helpful for anything.
As soon as the word "calories" comes up, one thinks of calories burned by the body, but this is not happening.

As a measure of the total amount of work you've done. While Calorie (especially capitalized which is really Kcalorie) connotes dietary food energy, it is a well defined unit of energy, like the Joule. It doesn't matter what you call it, or the fact that it is multiplied by a nonsense factor. It is still a measure of the overall workout.

So if you want to track your training volume you can either use watts times minutes (giving you 60 time kJoules) or use calories - 150*hours (giving you some multiple of kJoules that one could calculate from the C2 documentation).

It doesn't really matter which you use, so long as you are consistent. As I have noted in previous posts, I'd sooner have the PM5 simply read out kJoules, to avoid having to do this calculation.

Sakly wrote: ↑

July 5th, 2025, 5:25 pm

And that's the fallacy.
Watts and splits show you exactly what power is put into the machine. A physical measurement.

Measured rotations give you Computed Watts, Split and Calories. All are equally good measures of the output of your rowing on the flywheel, not what is put into the machine.

One is an underreported number that excludes your moving body weight and rowing technique, and is incorrect on large rev/sec changes. (watts)

One is a fictional boat speed number based on a huge number of assumptions including all in the watts computation that has evolved to be the de-facto indoor erging standard metric. (split)

One is a equally good measure of external output as watts that can also be used with a huge number of assumptions to give food intake vs external output with so much error range (even weight adjusted) that it's useless for anything except rough magnitudes and motivation. (Calories)

People should use whatever metric they want. They all work the same.

Should be clear, that I don't write about calories as a converted metric to log workout intensity. Everyone referring to calories typically does that to monitor "burnt" calories through the day.

So again, one metric is a physical measurement (even if only the flywheel speed is measured and the derived metric is based on many FIXED assumptions, which are glued into some fancy calculations to get the metrics from the flywheel speed/deceleration - it is still a physical measurement), the other is guesswork and fully useless to track calories (which is useless anyway in my opinion).