# Calorie Expenditure...



## cookieMonster (Feb 23, 2004)

Hey guys and gals. I've been on a pretty aggressive weight loss regimen lately and I've always wondered how many calories I'm actually burning. I can't seem to find a calorie calculator that truly reflects what I do on the mountain bike -- they all seem to be tailored to road biking or "cycling" lol. Anyway, "cycling" for 50 minutes does not necessarily mean the same thing as "doing 50 minutes of nonstop climbing on an 11% grade" -- which is a ride I do about 3 times a week.

I'm just trying to get a ballpark of calories burnt when I do my rides so that I can reliably plan my meals and maintain a caloric deficit.

As stated, typical rides for me involve a ~1200-1800' climb in 3.5 - 5 miles, respectively, which takes about 40-60 minutes on average. I don't really figure the downhill into the calories. I weigh 204 pounds and ride a 35 pound bike.

Thanks for any input!


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## Impetus (Aug 10, 2014)

Invest in a decent heartrate monitor. It's not going to be a perfect science, because HR fluctuates a fair bit on a bike (more than running) and calories burned is best calculated by heartrate and VO2 over time, not speed/distance. Particularly for MTB where you can be pegged out on max HR but literally moving at walk pace, and then immediately coast and blast up to 20mph with zero energy spent. From experience, not even the apps made for cycling like Strava or MapMyRide are that accurate when compared to a HRM. 

TL;DR- everything is modest accuracy at best. HRM with settings for gender, weight and max HR is closest, an app that factors in elevation/grade would be passable but not great, any website that just inputs time multiplied by distance is garbage.


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## Legbacon (Jan 20, 2004)

I don't know how accurate it is but Strava has your weight, elevation, speed, distance, and gives calories used. Likely pretty rough estimate.


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## Impetus (Aug 10, 2014)

I haven't used Strava specifically, but endomondo, mapmyrun, and runkeeper all failed miserably at estimating calories while running, which has inherently less variation because of no coasting while on feet. I used them all to track mileage and calories I needed to replace while training for my last marathon.
Maybe Strava is better. It's certainly worth a try, to get a ballpark, but I wouldn't use it to figure calorie balance.


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## Le Duke (Mar 23, 2009)

Get a power meter. Actually measures the number of kilojoules you are producing/burning (power * time).

The only accurate method out there. Everything else is bunk.


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## gsa103 (Sep 1, 2014)

Le Duke said:


> Get a power meter. Actually measures the number of kilojoules you are producing/burning (power * time).
> 
> The only accurate method out there. Everything else is bunk.


HRM and power meters have approximately equal accuracy for calories. Power meters do a better job with short (<1 min) efforts, but beyond that, the better HRM algorithms are equal to a power meter.

The limitations with power meters have to do with the metabolic efficiency between work and calories burned. If you get a instrumented lab test measuring your efficiency by looking at VO2, then a power meter is much more accurate.

Anything that is not a HRM or power meter is totally worthless. The estimates are laughably far off, such that its impossible to use them for any sort of diet regimen.


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## Alias530 (Apr 1, 2013)

Not cheap but a power meter is the only way to truly know calories burned. Everything else is guesswork, too many variables--tire width, tire pressure, tire rubber compound, body positioning, wind speed/direction, aero features of your clothing/bike/everything, temperature, hydration levels, fitness level, and on and on.

Power meters will display output in KJ which converts to calories. There's about 4.2 KJ in 1 calorie but your body is only 23-25% efficient at turning food into energy and the rest is lost as heat, so once you factor for loss in efficiency it's almost a direct conversion from KJ to calories.

Stages makes a left crank arm power meter, probably the cheapest option. There are other cheap options like the Powertab hub but you need to either build a new wheel or rebuild your current one, which will likely need new spokes (difference in length).


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## cookieMonster (Feb 23, 2004)

Lol thanks for the responses guys! I don't need to be near that accurate, as I'll log a very conservative estimate anyway. So if someone told me an hour of grueling climbing on a 35 pound FR bike might burn around 1200 calories, I'd probably log 700 just to be on the conservative side.


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## c8stom (May 19, 2015)

For what it's worth, I have been using Strava and also a Polar RS2 watch with heart rate monitor during all my rides in the past 4 months. I have kept a record of all the stats as I too was trying to lose a few lbs and wanted to monitor various parameters.

I noticed the accuracy of Strava varies depending on the Average Heart Rate

% of HRMax Strava 
60% Over estimates Kcals by up to 25%
65% Matches within 15%
70% Matches within 15%
75% Under estimates Kcals by up to 25%
80% Under estimates Kcals by up to 35%

The errors could be because Strava.
1. does not factor in temperature
2. does not factor wind resistance/assistance
3. does not factor topography that well
4. only includes Kcals when in motion ( excludes KCals at rest during breaks )
4. is calibrated for training zone in 65% and 70% ?

The Strava algorithm seems to assume the user is training between 65% and 70% of their max heart rate. As you move further away from this zone, the accuracy drops quite quickly

I live in asia where the temperature is currently 33 to 37 degrees C and I ride mostly at 75% HRMax so I will probably see bigger errors than others who live in cooler countries.

That said, Strava is a great FREE app and is definitely good enough for ballpark numbers though I use it for it's GPS features.


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## Le Duke (Mar 23, 2009)

cookieMonster said:


> Lol thanks for the responses guys! I don't need to be near that accurate, as I'll log a very conservative estimate anyway. So if someone told me an hour of grueling climbing on a 35 pound FR bike might burn around 1200 calories, I'd probably log 700 just to be on the conservative side.


First and foremost, the weight of your bike has nothing to do with calories burned. So just toss that in the bin right now.

It's wattage * time, or HR * time. That's it. If you're riding at 300w, you're riding at 300w. You don't magically burn more calories at 300w on one bike vs. another.

Or, more specifically ((wattage * time) / (joules/cal)) / efficiency %.

At 100w for an hour, at 24% efficiency (humans range from 20-25% efficient, increasing with fitness and other factors), it would look like this:

((100w * 3600s) / 4.18) / 0.24 = 358.851 calories

The problem with HR is that it doesn't account for environmental and biological factors such as heat, humidity, cardiac drift, dehydration, etc. On a hot day, you could be pedalling at 250w at 150bpm at the start of the ride, and your HR could be at 165 for the same workload at the end. Per the HRM, you'd be working 10% harder, but you aren't.


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## Tystevens (Nov 2, 2011)

I love it when I get done with a difficult tech 2000 ft climb mtb ride over 90 minutes, legs spent and body tired, and MyFitnessPal logs me in as a "bicycle ride, leisurely, 10 mph average ..." and gives me 600 calories for the effort (I have MFP linked to Strava, FWIW). Then, I can go on a comparatively easy, flat road bike ride for an hour at 16 mph and I get marked at 900 calories for that effort!

Like others have said, other than a power meter, not really a great way to get accurate numbers.


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## c8stom (May 19, 2015)

Le Duke said:


> On a hot day, you could be pedalling at 250w at 150bpm at the start of the ride, and your HR could be at 165 for the same workload at the end. Per the HRM, you'd be working 10% harder, but you aren't.


From a conservation of energy perspective, your example does highlight a potential anomaly. However, as we're talking about calorie expenditure in the human body, we need to include the body into the overall system.

There is alot of research evidence which shows the body requires more calories after it has been exposed to prolonged heat such as riding hard on a hot day. As dehydration sets in and the body gets hotter, the body requires more calories to cool itself by pumping more blood around. This explains why bpm at the end of the ride can be higher than at the start.

Although I think power meters have their place, I think calorie expenditure algorithms based on heart rate are still the most accurate.


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## borabora (Feb 16, 2011)

For me strava (with HRM) and separately some basic calorie counting have given me results that are roughly equivalent to 75% of total climbing in feet. In other words, a 2000' climb equals roughly a 1500 calorie expenditure including all the other riding associated with the ride. I am a bit lighter with a lighter bike but these are just estimates. An average ride with 2000' climbing for me would be 20 miles in maybe 2.5 hours.

If you are trying to lose weight then keep in mind that with regular exercise you also speed up your metabolism which ends up burning some more calories 24/7. The bad news is that as your conditioning increases your calorie burn rate goes down.


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## lanternrouge (Jun 29, 2015)

your size (close to mine) 600 to 800 calories an hour for a non JRA ride. I used to ride with a power meter and it's as close as you can get to actually quantifying your caloric expenditure. Now that I've moved to mountain I no longer have a PM but the numbers probably aren't, on average, that much different. 

A long climb of 1 hour is going to be closer to 800 ish, a normal rolling ride closer to the lower end. 

If you have to be exact though you really need a PM. It's actually measuring precisely how much energy you've expended for a particular effort. calories based on HRM is a much less precise number.


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## c8stom (May 19, 2015)

lanternrouge said:


> I used to ride with a power meter and it's as close as you can get to actually quantifying your caloric expenditure.


Let's take a sprint scenario. Let's suppose you apply full power for 10 seconds to accelerate and then stop pedalling completely for a further 10 seconds. How many calories was expended during the 20 seconds and beyond ?

1. With a HR, your heart rate is captured during the entire 20 seconds and a calories expenditure calculated based on that. It captures both the acceleration and the at rest phase.

Beyond 20 seconds, if you are fit, your heart rate having gone up quickly will return to normal quickly resulting in fewer calories. If you are unfit, your heart rate will take much longer to return to normal resulting in more calories expended than a fit person which is known to be true. Fit people are more efficient

2. With a power meter, it captures the power in the first 10 seconds but after the pedals stop turning, it stops registering power. However, the heart might still be pumping at 80% HRMax which requires calories. In other words, power meters completely ignore Basal Metabolic Rate ( BMR) requirements aswell as recovery requirements. This is expected as power meters are for measuring power.

Beyond 20 seconds, the power meter won't capture anything.


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## vancouver (Feb 17, 2012)

cookieMonster said:


> Hey guys and gals. I've been on a pretty aggressive weight loss regimen lately and I've always wondered how many calories I'm actually burning. I can't seem to find a calorie calculator that truly reflects what I do on the mountain bike -- they all seem to be tailored to road biking or "cycling" lol. Anyway, "cycling" for 50 minutes does not necessarily mean the same thing as "doing 50 minutes of nonstop climbing on an 11% grade" -- which is a ride I do about 3 times a week.
> 
> I'm just trying to get a ballpark of calories burnt when I do my rides so that I can reliably plan my meals and maintain a caloric deficit.
> 
> ...


I would suggest you look at a sports watch like Suunto, Polar or Garmin.

I have used a Suunto T6d and both their movescount program and the one by Firstbeat.

You need a variety of parameters to get a relatively accurate reading and assuming that the algorithms are accurate as well.

For an 1800-1900 foot fire road climb (Mt Fromme) to Seventh secret and down to the bottom on mixed technical trails is 9.3 miles total. That takes around 2 hours and change.

I'm using around 2200 kcals for that ride according to the watch and programs for example. 34 lb all mountain bike and I'm 219 right now plus around 10-12 pounds of additional gear/water.

Your weight, heart rate, mets (hours of training per week) vo2 max which is related to mets all are factors in energy expenditure along with max hr etc.

A good program with an accurate watch can cover all these bases.


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## c8stom (May 19, 2015)

Polars are really good and cheap. Their HR algorthim is one of the best having been tweaked for decades. 

Regarding weight loss, I recently lost 25lbs in 10 weeks to reach a BMI of 23.5. The key is to set the correct calorie intake. For my gender, size, activity level etc, I had set 1600 Kcals a day which I stuck to eating a balanced diet. If I exercised more on any given day, I made sure I consumed 200 more calories in the form of protein ( eggs, protein shake ). The weight dropped off quickly and has not bounced back.

What I would warn you against is what a lot of people on diets do is count the calories they've expended on their devices then believe they can eat more based on the overstated numbers therefore cancelling out their hard work. The best way is to set a healthy daily target calorie intake and stick to it. Whether you have devices or not, it will work


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## lanternrouge (Jun 29, 2015)

c8stom said:


> Let's take a sprint scenario. Let's suppose you apply full power for 10 seconds to accelerate and then stop pedalling completely for a further 10 seconds. How many calories was expended during the 20 seconds and beyond ?
> 
> 1. With a HR, your heart rate is captured during the entire 20 seconds and a calories expenditure calculated based on that. It captures both the acceleration and the at rest phase.
> 
> ...


You are correct that the HR pumping beyond the actual effort requires calories but nowhere near the number of calories required to do the actual work involved in a 10 second sprint, 10 minute climb or 60 min threshold effort. The actual work done in moving your mass from point a to b is what matters. This is what the power meter measures.

From your first example if you do 1000 watts for 10 seconds then rest for 20 seconds you've averaged 500 watts for those 20 seconds.

Either way the amount of energy you actual expended to move your body for those 20 seconds is the same regardless of how you averaged your 500 watts.

The HR overrun from the effort while not meaningless is really lost in the noise.

Beyond those 20 seconds the PM will capture whatever effort you do or don't make. It can't capture your BMR of course but if the intent is to determine how many calories were expended as a direct result of a ride the PM is the most accurate device we have. One can just assume BMR for a given day from on of the various BMR calculators out there.

If my BMR is 1600/day maybe I can assume some small increase on the basis of a 1200 calorie (reported by PM) ride but I don't think that it is significant.

Judging by the articles and research a HRM is going to be especially bad at measuring sprint level effort caloric expenditure.

I'll look for some more relevant articles or research but here's a couple off the bat:

The Real Facts about HRMs and Calories -- What you need to know before purchasing an HRM (or using one)

Why Fitness Tracker Calorie Counts Are All Over the Map | WIRED


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## lanternrouge (Jun 29, 2015)

c8stom said:


> Let's take a sprint scenario. Let's suppose you apply full power for 10 seconds to accelerate and then stop pedalling completely for a further 10 seconds. How many calories was expended during the 20 seconds and beyond ?
> 
> 1. With a HR, your heart rate is captured during the entire 20 seconds and a calories expenditure calculated based on that. It captures both the acceleration and the at rest phase.
> 
> ...


You are correct that the HR pumping beyond the actual effort requires calories but nowhere near the number of calories required to do the actual work involved in a 10 second sprint, 10 minute climb or 60 min threshold effort. The actual work done in moving your mass from point a to b is what matters. This is what the power meter measures.

From your first example if you do 1000 watts for 10 seconds then rest for 20 seconds you've averaged 500 watts for those 20 seconds.

Either way the amount of energy you actual expended to move your body for those 20 seconds is the same regardless of how you averaged your 500 watts.

The HR overrun from the effort while not meaningless is really lost in the noise.

Beyond those 20 seconds the PM will capture whatever effort you do or don't make. It can't capture your BMR of course but if the intent is to determine how many calories were expended as a direct result of a ride the PM is the most accurate device we have. One can just assume BMR for a given day from on of the various BMR calculators out there.

If my BMR is 1600/day maybe I can assume some small increase on the basis of a 1200 calorie (reported by PM) ride but I don't think that it is significant.

Judging by the articles and research a HRM is going to be especially bad at measuring sprint level effort caloric expenditure.


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## c8stom (May 19, 2015)

lanternrouge said:


> You are correct that the HR pumping beyond the actual effort requires calories but nowhere near the number of calories required to do the actual work involved in a 10 second sprint, 10 minute climb or 60 min threshold effort. The actual work done in moving your mass from point a to b is what matters. This is what the power meter measures.


I don't think we will ever agree so maybe better to take the discussion offline. For the purposes of making a recommendation to the OP, what do you recommend ?

Given HRMs are good and cheap ranging in price from 100 to 250 usd, I would suggest the OP picks one up like a Polar or Garmin. Polar have fitness tests built in which help calibrate the watch. You get a lot for your money.

Power meters ?, ranging close to and well above 1000 USD, I think it's too expensive for the OP given her intended usage. More appropriate for someone who's training seriously to improve performance rather than losing weight in my view.

I could be wrong though..


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## cookieMonster (Feb 23, 2004)

Le Duke said:


> *First and foremost, the weight of your bike has nothing to do with calories burned. So just toss that in the bin right now.*
> 
> It's wattage * time, or HR * time. That's it. If you're riding at 300w, you're riding at 300w. You don't magically burn more calories at 300w on one bike vs. another.
> 
> Or, more specifically ((wattage * time) / (joules/cal)) / efficiency %.


I respectfully disagree. Energy (work) is calculated by multiplying force times distance, measured in joules. Energy (W) is part of the calculation in the power equation. (watts = joules/time). The part where the heavier bike comes in is that it has an effect on the amount of work (J) done. I agree that 300 watts is 300 watts. But certainly it takes more energy (calories) to move a heavier bike from point A to point B than it does to move a lighter one along the same route.

Anyway, this is WAY more in depth than I needed to get. I just wanted a ballpark figure. I realize it would be very difficult to calculate on a lot of trails, but the trails I ride are predominantly all climbing (and mostly at a 9-11% grade) until I reach a summit or a good turnaround point on an out-and-back. I'm pretty much _constantly_ at 65-75% max HR. My HR really doesn't fall below 65% until I stop to prepare for the descent.

Anyway, weight loss is done in the kitchen, not on the trails or at the gym. So far I've been successful; losing 10 pounds in about 7 weeks. I've got 10 to go though.


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## cookieMonster (Feb 23, 2004)

c8stom said:


> What I would warn you against is what a lot of people on diets do is count the calories they've expended on their devices then believe they can eat more based on the overstated numbers therefore cancelling out their hard work. The best way is to set a healthy daily target calorie intake and stick to it. Whether you have devices or not, it will work


You're absolutely right. I've approached this from the standpoint that I want to achieve some weight loss whether I exercise or not. And the more calories I burn riding my bike or some other form of work is just a bonus. I've been taking in an average of 2300 calories a day, but in addition to mountain biking, I am a landscaper all day -- which is hard work. I've been using a Fitbit to track what I eat and roughly how many calories I burn during the day just from walking. I don't know why it's taken me so long to figure out that you REALLY have to watch what you eat in order to lose weight, even if you work/workout like a madman. What I've really worked hard to cut out are desserts and excessive carbs in the form of breads and grains. Smaller, but more high-protein portions have really helped me with this. So far, what I've been doing is working great -- I've lost 10 pounds in about 7-8 weeks. But having 10 to go (and I may opt to lose even more after that), I just want to do everything I can.


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## asookazian (Mar 3, 2015)

Does the Apple Watch or any other smart watch help calculate calories burned?


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## asookazian (Mar 3, 2015)

cookieMonster said:


> I don't know why it's taken me so long to figure out that you REALLY have to watch what you eat in order to lose weight, even if you work/workout like a madman. What I've really worked hard to cut out are desserts and excessive carbs in the form of breads and grains. Smaller, but more high-protein portions have really helped me with this. So far, what I've been doing is working great -- I've lost 10 pounds in about 7-8 weeks. But having 10 to go (and I may opt to lose even more after that), I just want to do everything I can.


I'm 6' tall and dropped from 195 to 170 in 2-4 months last year by exercising about 2 hrs/day, dieting and using amphetamine temporarily. I'm now at 185+ and eating too much ice cream, breads, beer, other desserts. All useless stuff. But I exercise multiple times per week as well.

check out: The Fruitarian | The Fruitarian

ultra-runner only eats fruits supposedly. that may help but hard as hell to maintain and boring diet. not sure how healthy that is either. scott jurek is another vegan ultra-runner (skinny).


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## asookazian (Mar 3, 2015)

Oh and of course, you REALLY have to watch what you eat the older you get. Not so much in your teens/20's if you're active.


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## asookazian (Mar 3, 2015)

Apple watch calorie counter is off apparently:

https://discussions.apple.com/thread/7018370?start=30&tstart=0


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## lanternrouge (Jun 29, 2015)

c8stom said:


> I don't think we will ever agree so maybe better to take the discussion offline. For the purposes of making a recommendation to the OP, what do you recommend ?
> 
> Given HRMs are good and cheap ranging in price from 100 to 250 usd, I would suggest the OP picks one up like a Polar or Garmin. Polar have fitness tests built in which help calibrate the watch. You get a lot for your money.
> 
> ...


Well, for purposes of the OP a HRM is the best/cheapest thing. PMs are definitely too expensive to justify for purely calorie counting reasons. However I still think they are more accurate


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## c8stom (May 19, 2015)

lanternrouge said:


> Well, for purposes of the OP a HRM is the best/cheapest thing. PMs are definitely too expensive to justify for purely calorie counting reasons. However I still think they are more accurate


Perhaps start a new thread "HRM vs PM for calorie counting". See you in the ring ! :madmax: hee hee


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## c8stom (May 19, 2015)

asookazian said:


> Apple watch calorie counter is off apparently:
> 
> https://discussions.apple.com/thread/7018370?start=30&tstart=0


Not surprising really. A few friends also use the Fitbit and JawBone and have so far been equally unimpressed. They are fun and feature packed but not accurate for heavy workouts / exercise.

it would be far better to stick to companies which have a long history in fitness metrics


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## cookieMonster (Feb 23, 2004)

borabora said:


> For me strava (with HRM) and separately some basic calorie counting have given me results that are roughly equivalent to 75% of total climbing in feet. In other words, a 2000' climb equals roughly a 1500 calorie expenditure including all the other riding associated with the ride. I am a bit lighter with a lighter bike but these are just estimates. An average ride with 2000' climbing for me would be 20 miles in maybe 2.5 hours.
> 
> If you are trying to lose weight then keep in mind that with regular exercise you also speed up your metabolism which ends up burning some more calories 24/7. The bad news is that as your conditioning increases your calorie burn rate goes down.


Thank you for that. Today I did a ride and used that 75% of the vertical feet climbed formula (except I was real conservative and used 60% instead. Today's ride, as well as most of the rides I do are what I would call "grueling." It was a 2200' climb in 4.6 miles. It took me exactly 1:30 to reach the summit. At 60% of the vertical feet climbed, it came out at 1320 calories. Judging by how exhausting the ride was, this seems very reasonable; I probably burned more than that. Most of the rides I do are constant uphill with no breaks until I get to the top. I don't have an HRM, but I would guess that my HR rarely fell below 65% on this ride and most of what I do. There were a few stretches where I was close to redlining, but the steepness gave way just before that point. This is not friendly rolling XC-type terrain. I actually wish we had some trails like that! But your formula seems like a good way to get a solid estimate, considering the type of trails I ride.


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## Cleared2land (Aug 31, 2012)

I have monitored my caloric burn rates on both Garmin Connect and Strava and the two incorporate slightly different algorithms. From the best that I have been able to determine is that none of the used algorithms use elevation or climb gradients, bike weight or your size. Your overall total weight is in the equation. The predominate factor in addition to weight is your heart rate. If your heart rate is not included in the equation, then the output or caloric burn is just an estimated linear guess.

Additionally, I have noted that in my personal case, Strava places a predominate emphasis on the duration more than does Garmin Connect. That meaning that for me, Strava indicates a greater calorie burn for the same ride than Garmin Connect does.

*Calories Burned = [ (age in years x 0.2017) + (weight in lbs. x 0.0904)+ (heart rate x 0.6309) - 55.0969] x duration in minutes / 4.184*

This is clearly subjective from several perspectives, but I have found it closely emulates my performance. Tweak as necessary to find what works best for your objectives.


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## element1 (Aug 6, 2009)

I wonder...on this same note...has anyone figured what they burn downhilling all day? Wore a HR monitor while downhilling for a day? I also DH on the weekends, wondered if its exercise and/or counting towards my regular workouts on the bike. We ride pretty hard, I have a DH specific bike etc. It's not just a coast. Live out in CO, have a ton of good lift access terrain. Not seem much in internet searches on this. Thanks!!


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## asookazian (Mar 3, 2015)

element1 said:


> I wonder...on this same note...has anyone figured what they burn downhilling all day? Wore a HR monitor while downhilling for a day? I also DH on the weekends, wondered if its exercise and/or counting towards my regular workouts on the bike. We ride pretty hard, I have a DH specific bike etc. It's not just a coast. Live out in CO, have a ton of good lift access terrain. Not seem much in internet searches on this. Thanks!!


From my limited experience on SoCal fire roads, DH burns far fewer calories compared to uphill or running. Unless you're pedaling downhill or turning frequently with jumps, etc. (which I typically don't do).

In fact, DH requires great skill and experience to do fast and with great accuracy and no crashing. But I don't consider it a real cardio or resistance workout compared to other sports.


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## element1 (Aug 6, 2009)

asookazian said:


> From my limited experience on SoCal fire roads, DH burns far fewer calories compared to uphill or running. Unless you're pedaling downhill or turning frequently with jumps, etc. (which I typically don't do).
> 
> In fact, DH requires great skill and experience to do fast and with great accuracy and no crashing. But I don't consider it a real cardio or resistance workout compared to other sports.


I have to say though I feel out of breath (adrenaline perhaps) and my entire body is tense, muscles start to cramp, hurt, my gluts are always sore so maybe its more of a strength workout. Or similar to the energy expenditures with dirt biking I wonder.


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