bung

I am counting calories as part of my training and I have previously used Workouts on my Apple Watch for those calculations. I recently started using the wahoo fitness app along with the Tickr strap and share that data with my calorie counting app. I ride with the workout app running on my watch and wahoo running on my phone. I found that the calorie count from wahoo is MUCH higher than that of the workout app. I see that wahoo publishes their algorithm for calories burned but I can’t find it for apple. So, is the Apple algorithm too low and the wahoo algorithm too high or vice versus?

Greenhil

I find that Wahoo give me lower calorie counts than Ride With GPS when both are connected to a chest strap heart rate monitor. Also much lower than a diet app I use (Chronometer) which doesn’t monitor heart rate. You’ve probably seen the little disclaimer on the Wahoo app calorie reading and the algorithm explanation. I’d love to know how to get a halfway reliable way to get an accurate number.

Iride01 

Comparing Calorie counts from different devices is madness. There are too many factors that may be different in the way they arrive at the number they show you. Pick one to go by and ignore the others.

If you have to have a consistent number for every same ride you do, then just use a formula and calculate it. If you want the most accurate and close approximation, then get a power meter.

Seattle Forrest

​​​​​​Power meter.

jpescatore

If you can't train with power, the simplest approach is either to use the lowest, or use a simple standard number per mile of your own.

For example, I generally use 10 calories/minute or 40 calories per mile (there is really a k in front of those, yes) since on mixed terrain rides I'll usually average between 15 - 17 miles an hour. That is lower than what most fitness software (let alone gym equipment!) will report but feels closer to reality to me over the years - and I'd rather err low than high.

On Zwift rides on a smart trainer where it gets both heart rate and power readings and knows my weight but also the speeds tend to be inflated, the 40 calories per mile seems to be pretty much in the middle of what Zwift calculates - too high on rides I do at lower average power, too low on rides I do at higher average power levels.

Seattle Forrest

If cycling is the only exercise you do, and you're tracking calories, you can get an idea over about a month of how much weight you should have lost vs how much you actually did. That won't account for other activity or differences in hydration, but it should give you a general idea how much to trust your numbers.

surak

RWGPS and calories vs Wahoo Bolt w power meter

Anything using just heart rate is going to be inaccurate because there's such a huge variance. For someone with higher typical heart rate, the Wahoo majorly overestimates. From that post, you'll see multiple posters with power meters that noted how extremely off Wahoo's calorie burn estimates are.

Iride01 

I would't even attempt to use Calories derived from HR monitor/gps and such to analyze my performance. About all they are good for and I think what they are intended by the mfr's for is to help you for dietary needs. IE, did you burn enough Calories to eat that piece of cake with inch thick icing and eat a bowl of ice cream?

And if that is the purpose of the OP, then do you also record your Calories consumed with the same precision and use a scale for everything you eat?

The information from power meters can be used to aid in analyzing your performance, because it measures a value it can more directly measure. HR monitors and such can only guesstimate and there are many ways for them to be inconsistent.

ZHVelo

My fitbit provides quite good estimates of calories burned when compared to power meter outputs. For example, 909 compared to the 965 from Wahoo/Strava based on power meter. I think that is not too bad. Especially considering my overall calorie use that day was 2900, a 56 calorie difference isn't all that much.

OBoile

Yep. And, as someone with a PM and a Wahoo computer, I find that the Wahoo (which is based on HR) consistently overestimates my calories burned. Of course, Strava uses the supplied (Wahoo) number rather than calculating based on kj It bugs me enough that I filed a ticket with Wahoo about it.

Iride01 

But what is the kiloJoules representing that was put out by the power meter? Is it simply a straight conversion of total watts to kiloJoules or kilocalories? Or does it represent the amount of Calories that the body burned to put out that amount of work?

Many of the articles I've read say that as little as 25% of the energy burned by a human body gets delivered to the pedals. So if, as I believe, the HR monitors and other devices are concerned with calculating a dietary Calorie, then they should be reporting a higher number.

The reason a power meter is useful for training is it reports what was delivered to the bicycle. Not what your body produced to get it there. A dietary Calorie total will vary depending on all sorts of factors.

Did the OP ever say whether they were interested in a Calorie for diet management or a Calorie/kilojoule for performance?

burnthesheep

For the naysayers.........you can often get used meters on Ebay for like $250. Some folks blow that on some high end shorts and top.

I've got two used Stages meters. Never an issue in years. I spent under $200 on one and about $250 on the other one.

A meter......just count the KJ's as-is.

HR is wildly inaccurate for calorie count. HR responds slowly to peaks and valleys in your work. You could be slowly bringing the HR down a hill for a minute or two but doing ZERO work. But guess what, as your HR ramps down you still accumulate calories. A meter doesn't accumulate anything in that scenario.

Seattle Forrest

1 watt = 1 joule per second.

The total kJ or mJ reported from a direct force power meter is extremely accurate. There isn't a better source.

Converting joules to dietary calories (which are exactly the same as exercise usage calories) has a maximum error of 5% and the way it's most commonly done puts you in the middle of that range. Yielding a maximum error of +/- 2.5%. Over the course of a 2,000 kJ ride (mountainous half century in my case) that's one Oreo of uncertainty.

The only way to get better accuracy of dietary calories than a power meter is to use a metabolic ward.

Good heart rate monitors are very accurate at counting heart beats. But how many heart beats are there in a calorie?

merlinextraligh

1 dietary calorie is equal to 4.18 KJ. So if we were perfectly efficient you'd have to put out 418 kJ to burn 100 calories. But , we're only about 18-23 % efficient.

Thus 1 KJ output on the power meter will roughly equal 1 calorie burned. If you want to be a bit more precise, 1 KJ to 1.1 calories will be accurate for almost everyone to 5% +/-.

Allen Lim had a piece on this that explains it well. Not sure you can still find it on line. It's quoted in old threads on BF.

For most purposes though just assume 1 KJ out put equals 1 dietary calorie and you'll be fine.

Iride01 

And I'm in total agreement that power meters are generally the most reliable and more accurate method to track a dietary Calorie for diet purposes. However most articles do state that power meters under estimate dietary Calories by upwards of around five percent or so.

My argument is not with those using power meters at all. It's those that compare one with the other. Frequently people say their HR monitor is higher on Calorie burn than what their power meter gives. Those that give figures to compare against are frequent close enough to that five percent of difference.

Also, HR monitors have been giving Calorie burn since before wattage was even a thing to easily train by. That is why I maintain that these devices only give Calories for the purpose of diet. Those Calories are a best guess based on several variable factors that are based on averages. There is no way that figure would ever be intended for training or performance evaluation. IMO. On those type devices, it's just for figuring out how much you can eat. And since most people don't track their intake of Calories, it's very useless and only a Gee-Whiz number. Even if a person did track their Calorie intake by weighing every morsel they consumed, there are too many variables in whether or not that piece of food has the content of the average it's based on.

The advent of power meters for cycling is what made training by power possible for the masses. No one should try to use power training plans with out a power meter.

For dieting, you can use what ever you want. Just use one though, because comparing is madness. If you gain weight then reduce your intake or increase your burn or vice versa if you loose to much or too fast. Don't worry about the what the actual expended and intake Calorie numbers are. Just increase of decrease them relative to each other to achieve the results desired.

surak

Wahoo wishes they were within 5%. 🙄

DrIsotope

^^^

Well-- and this is not a defense of Wahoo's refusal to calculate calories via PM if one is present, I think that is ridiculous-- your HR on that ride is through the roof, unless your LTHR is like 175bpm. A TSS of 147 for 30 miles is crankin'. You can forgive the algorithm a little on that one.

surak

My LTHR is 174 (unless my Wahoo HRM has been defective for the 2+ years I've used it, in which case minus another point for them), and I put that and my max HR into my Wahoo Fitness profile for HR zones, not that it does anything with the additional knowledge.

That ride was actually a round trip commute where I was at my office for a couple hours in the middle, but yes I'm typically have an IF around 0.9 on my one-way commutes.

merlinextraligh

Problem is that if your Power meter indicates 1000 calories, and Wahoo indicates 1700 calories, if you use the 1700 for dietary purposes you’re going to get fat.

So if you have a power meter use it. If you don’t, realize that the numbers from other non power based devices may substantially inflate the calorie burn

Seattle Forrest

The OP said he's counting calories as part of his training. I took that to mean trying to get lean for the season while also getting stronger. And specific to the counting, I took that to mean counting what goes in, and what goes out with exercise. Because eating too little is going to stand in the way of getting stronger at some point. But eating too much means carrying fat around for all those miles when it isn't helping you.

A power meter has a maximum error of 5% for dietary calories. In this thread we have an example of a heart rate system being 70% over. If you go by that number for something you do routinely, you're going to lose weight. Heart rate monitors are notoriously generous and not in the right ballpark.

OBoile

I'm not going to go back and dig up my results (haven't used my wahoo bolt since the fall), but the difference was similar in magnitude to this. 5% is a pipe dream for me.

DrIsotope

Immeasurably happy to report that as of the 5/27 firmware update, Wahoo computers are now using power data (when present) for calories.

ELEMNT WF48-7697 - 27 May, 2020

• Added: Japanese translation fixes
• Added: Calorie calculations from a power source
• Updated: Calorie calculation from a HR source

Woo hoo!!

OBoile

Nice! I just checked my last ride... and it seems to be working as intended. 1417 kJ and 1400 calories burned.
A similar ride on May 23rd was 1449 kJ and 1868 calories.
I submitted a request for this feature maybe 8 or 9 months ago. Maybe they actually listened to me?

clasher

I noticed this change too, that's pretty handy. I've long been of the habit of just using the kJ number for calories, even for estimated power on strava it seemed a more realistic number than the wahoo calorie one. I wonder how they mangled the old calculations so badly.

Puhovpeny

Are you kidding ?