Training & Nutrition - The myth of 40 cal/mile

So I've been watching and participating in this board a fair amount over the past few months, and I've seen a number of times where people quote that cyclists burn between 35 and 40 calories per mile. I mean, some people almost seem to take that range as gospel. So, I wanted to know where this number came from. Could I find any study or reference to support this claim? If so, what were the suppositions around which the claim was based?

The short answer: I couldn't find any reference that said this range was correct, but I found a number that indicate this range is incorrect, especially for heavier riders.

For example, one place I went was HowStuffWorks.com. They have a link from there to a table that actually comes from the Schools of California Online Resources for Education (SCORE) Mathematics lessons. That table, linked to

Sorry. Hit the wrong frigging button.

Anyway, that study, linked to here (http://score.kings.k12.ca.us/lessons/calories/calorieburn.html), gives calories per minute expended for biking on a flat surface, with no wind resistance. You run through the formula

Cal/Mile = (Cal/Min * Weight * 60) / MPH

For a 150 pound individual going 15 MPH, you get 29.4 Cal/Mi. For that same person going 25, you get 50.04 MPH. For a 200 pound person, you get 39.2 and 66.72 Cal/Mi, respectively.

Remember that this doesn't take into account terrain, bike, or wind conditions. This is riding in ideal conditions.

So, you say, use the calculator like this one (http://www.kreuzotter.de/english/espeed.htm). Well, the calculator has problems too. For one thing, it assumes that you're going up or down a constant slope. For another, it assumes that the wind is coming at the same rate from the same direction throughout your ride. Finally, it assumes that you're only 25% efficient in your calorie burn. None of these assumptions are necessarily true.

Lets assume that I'm a 6 foot, 200 pound rider on a 40 pound MTB doing a 2-mile 5 degree slope, at sea level and 68 degrees Fahrenheit. There is no wind. Erasing the Power field, we assume that going down I can go at 24 MPH. The trip down took 5 min. The calcualtor says that the distance covered was 2 miles, 0.1 so that's not too bad. It says that that trip down consumed 0 calories (a negative power value), so I must have been coasting. The trip back up, on the other hand, at 75 RPM would have taken just over 17 minutes and consumed 203 calories, or 101.5 calories/mile.

If I ride down and back, the effective elevation change is 0. This ride would have been 4 miles, with an average cadence of 75, since the cadence down was 0. The average speed would have been ((2 * 24) + (7 * 17)) / 9 = 18.55 MPH. In this case, I expended 192 calories, or just under 50 Cal/Mi.

So where did the 40 Cal/Mi number come from? Can anyone give me a citation?

BTW, RiderX has a good article on the whole tables vs. calculator vs. HRM debate here (http://riderx.info/blogs/riderx/archive/2007/08/08/figuring-calories-per-mile.aspx). Interesting reading.

there all just estimates when you get down to it. the only way to accurately determine calorie expenditures is in the science lab. as for where the 40 cal/mi came or supporting documentation/studies for it i have none. later.

Yup. Estimate or guesstimate at best. I would hazard a guess that most cyclists would not want to spend the time entering 20 different stats into a long equation to get a more accurate number.

No matter how many parameters you enter into a web calculator, or your GPS feeds back to you, it's all just a guess, a rationalization. And I think the guess is usually an over-estimate, even 40kcal/mile is pretty generous rule of thumb but not crazy. About the only actually useful data you can use to infer calories burned with precision is output from a powermeter. Watts are power and can be back-calculated to calories.

Well I have power meter on my bike, so assuming to do 1Kj of work body uses ~1Cal the range is somewhere between 30-40, depending on intensity of the ride. If you really want to I can go through my power files and give you more numbers, with average speeds (which in real world are kind of useless).
Although when you get down to it, as everyone said it's just a guess. A starting point to narrowing down your caloric needs for the day. Personally I think 40 is a really big over estimation, for most people it falls around 30.

According to my HRM, which is course just an estimate of my metabolism based on my age, weight, height, and heart rate, usually gets around 1000 calories per 25 miles, which is 40 cal per mile. Its more if its a lot of climbing, or a fast pace (e.g. racing)

This is from the February7, 2001 edition of "The Heart Zones e-Newsletter (http://www.heartzones.com/newsletter/archive/newsletter020701.htm):


4. How accurate is the calorie counter, a feature in some of the new heart rate monitors?

Measuring calories burned when exercising can be accurate if you have access to sophisticated testing equipment. Otherwise, all caloric expenditure information that you read off of a heart monitor or an exercise machine like a treadmill or indoor bike, are estimates of calories spent and usually not very accurate. Polar, the Finnish company that manufacturers excellent heart rate monitors decided to test their monitors against the best laboratory equipment made. There goal was to determine the accuracy of using a Polar heart monitor and therefore, the value of looking at caloric expenditure using their monitor. In research that they sponsored, they took their Polar SmartEdge for a road test against a Cosmed (K4, Italy) that accurately measures energy costs when exercising. “In two thirds of the subjects, the difference between the values of the two pieces of apparatus was less than 15% during cycling and walking, which was considered satisfactory”. Their assessment that an error of less than 15% is satisfactory is probably the most accurate of all – it’s satisfactory.

Just a little more information.

And, by the way, you can now get a bike powermeter from iBike (http://www.ibikesports.com/products.html) for $400 - $500, depending on your preference for cadence. A much better price than they used to be.

I can understand how your calories per mile can vary with terrain conditions and with wind resistance however what i wonder is the following: assuming wind resistance is zero, the terrain is completely flat that whether your ride at 25 mph or 15 mph, you should burn the same amount of calories having gone the same amount of distance.

My reasoning comes from excerpts i've read stating the running 3 miles and walking 3 miles burns the same amount of calories. I've always found this hard to believe because the exertion and level of difficulty seems alot higher running those 3 miles versus walking---basically, despite being for a shorter amount of time, it seems like alot more work.

http://www.weightlossresource.com/tools/exercise/calculator1_2.cfm

I can understand how your calories per mile can vary with terrain conditions and with wind resistance however what i wonder is the following: assuming wind resistance is zero, the terrain is completely flat that whether your ride at 25 mph or 15 mph, you should burn the same amount of calories having gone the same amount of distance.

My reasoning comes from excerpts i've read stating the running 3 miles and walking 3 miles burns the same amount of calories. I've always found this hard to believe because the exertion and level of difficulty seems alot higher running those 3 miles versus walking---basically, despite being for a shorter amount of time, it seems like alot more work.Unless you're running and cycling on the moon, air-resistance is ALWAYS a factor and MUST be incorporated into your models. Running and walking doesn't have much of a difference in terms of air-resistance. However, with cycling, going from 15mph to 25mph increases wind-resistance by 2.7x and requires 4.6x more power to overcome that increase in drag. This dramatic increase in power requirements is why you get lower gas mileage at higher speeds on cars.

Check out this site: http://www.kreuzotter.de/english/espeed.htm

Using the default settings with road-bike, with hands in the drops, zero-elevation and medium-wide tyres, we get:

15mph = 91w = 21 Calories/mile
20mph = 185w = 32 Calories/mile
25mph = 333w = 46 Calories/mile

I would say that the typical estimates of 40 cal/mile is too high, most people are not in that kind of shape, especially the ones who are wondering about cal/mile. So I'd say 20-30 cal/mile is a more accurate assessment.

Also "typical" folks ride in a narrow range of average speeds, around 14-18mph. Looking at the power-needed graph:
http://damonrinard.com/aero/grafik2.gif

You can see that the slope of the "total" curve from 10-20mph is faily linear, so most people assume that power-needed goes up linearly with speed. However, if you examine a wider speed-range, say 15-40mph, you'll easily see that power-requirements and energy-burnt goes up exponentially with speed due to non-linear increases in wind-resistance.

I can understand how your calories per mile can vary with terrain conditions and with wind resistance however what i wonder is the following: assuming wind resistance is zero, the terrain is completely flat that whether your ride at 25 mph or 15 mph, you should burn the same amount of calories having gone the same amount of distance.

My reasoning comes from excerpts i've read stating the running 3 miles and walking 3 miles burns the same amount of calories. I've always found this hard to believe because the exertion and level of difficulty seems alot higher running those 3 miles versus walking---basically, despite being for a shorter amount of time, it seems like alot more work.

No, because air resistance increases exponentially with speed. The aerodynamic difference between walking and running is MUCH lower than the difference between biking at 15mph vs. 25mph.

My reasoning comes from excerpts i've read stating the running 3 miles and walking 3 miles burns the same amount of calories. I've always found this hard to believe because the exertion and level of difficulty seems alot higher running those 3 miles versus walking---basically, despite being for a shorter amount of time, it seems like alot more work.

When you run or walk, you essentially are lifting one leg off the ground using your hanstring and quads and then pushing off with your foot/toes and also using your calves. You are burning calories from this effort. When you run, you are just doing it faster but you do it to cover the same distance so the calories walking a mile are in the same ballpark as running a mile.

I should add not only a wind resistance of zero but air resistance of zero. Basically, put yourself on an indoor bicycle and ride for 50 miles----once at 25mph and once at 15mph. I understand the basic concepts that the energy expenditure should be the same but it sure seems that there should be some difference in calorie expenditure.

I need some lab results to prove it :)

I should add not only a wind resistance of zero but air resistance of zero. Basically, put yourself on an indoor bicycle and ride for 50 miles----once at 25mph and once at 15mph. I understand the basic concepts that the energy expenditure should be the same but it sure seems that there should be some difference in calorie expenditure.

I need some lab results to prove it :)Well, on a stationary trainer, there's still wind/air-resistance from the wheels & spokes spinning through the air at different speeds. Sure it won't be as dramatic as out on the road, but there will still be a slight difference. Also look at that graph above and you'll see that drivetrain-drag and rolling-resistance does go up linearly with increased speed.

So on a stationary trainer, the calorie expenditures may be 1.25x higher in going from 15 -> 25mph, while out on the open road, it will be 2.00x higher. It also depends upon the trainer, mag/fluid trainers have a fairly linear increase in resistance with speed, while a wind/fan trainer will have an exponential increase.


Also there are different ways to measure "efficiency". There's oxygen-to-power and there's calories-to-power efficiency. Increased fitness through training will allow you to produce more power for the same oxygen processed. However, someone please point out a human that can generate more or less than 38 ATPs per glucose molecule... ;)

That dreaded air/wind resistance gets us no matter where we go eh? Indoor or outdoor. Now i wonder if caloric expenditure for different heart rates go up linearly as well. At my age maybe pushing 150 bpm at 15mph vs. 175 bpm at 25mph will the hearts caloric requirements be the same over the same distance?

Running also involves moving your body up and down much more so than walking. Thus, the "rule of thumb" for walking is around 90 calories per mile, while it's up around 120 calories per mile for running (plus or minus, depending on body weight and how much climbing is involved).

I should add not only a wind resistance of zero but air resistance of zero. Basically, put yourself on an indoor bicycle and ride for 50 miles----once at 25mph and once at 15mph. I understand the basic concepts that the energy expenditure should be the same but it sure seems that there should be some difference in calorie expenditure.

The energy difference would be small, but the time difference would be huge. So the cal/mile would be pretty close but the cal/min would be very different. And the fat/carb ratio burned would be different too.

Take it for what it's worth. 254 rides of data on a power meter. The trendline crosses at somewhere around 250 watts. But the plots start hitting 40 cal/mile consistently at 223-226 watts and hang out very close to that up to around 255ish. 220-250 watts is low, particular for someone overweight trying to shed pounds. The light weight folks would consider that mid/high, but that isn't the typical target audience for a 40 cal/mile estimate.

Anyway, like I said, take it for what it's worth.

VW

Nice plot NomadVW. You keep the best records... and I thought my training log was the most detailed/complicated around. :) Good Stuff.

Cut/paste from Cyclingpeaks, then make a handy pivotchart. Works every time. :)

Cut/paste from Cyclingpeaks, then make a handy pivotchart. Works every time. :)

Though.. I will add that my "personal training log" is a bit different than Cyclingpeaks. Cyclingpeaks is great, but it's not nearly as customizable as I'd like. I use this spreadsheet:

http://www.cycleiwakuni.com/download.php?file=Tsb-planner-07.xls

there all just estimates when you get down to it. the only way to accurately determine calorie expenditures is in the science lab. as for where the 40 cal/mi came or supporting documentation/studies for it i have none. later.

and a high estimate at that, for many riders.

VW nomad's numbers prolly come the closest for a good estimate, and that being for a very fit 160 lb-ish rider (if I remember reasonably correctly).

people think that just because they 'weigh' more, they expend more - often false.

40 Kcals per flat to gently rollin miles might be a 'solid' but not 'bury the hammer' kinda ride for VW nomad.
others may not even be able to approach this.

lets face it, the 40 Kcals/mile rationale is often just an excuse for another piece of pie ;)

Sorry to disagree, but the plot doesn't apply to most riders. Look at the legend. It says that it applies only to a typical RACING bicycle. How many of us ride that kind of bike? It also neglects to mention the weight of the rider.

Most of us don't ride racing bikes. Road bikes will have a higher curve. ATBs even higher than that. Add more still if you're carrying a lot of extra weight like panniers with your clothes and lunch, etc. What is the weight of the rider for that curve? I'd be willing to bet that I weigh a bit more than that rider did. All these contribute to a higher power requirement to reach the same MPH, so my Cal/Mi would be higher.

All that curve proves is that for a specific rider on a specific bike there is a specific curve. It is a sample of one. You can hardly draw a statistical generalization from that.

Take it for what it's worth. 254 rides of data on a power meter. The trendline crosses at somewhere around 250 watts. But the plots start hitting 40 cal/mile consistently at 223-226 watts and hang out very close to that up to around 255ish. 220-250 watts is low, particular for someone overweight trying to shed pounds. The light weight folks would consider that mid/high, but that isn't the typical target audience for a 40 cal/mile estimate.

Anyway, like I said, take it for what it's worth.

VW

Are those watts average for the ride?

It says that it applies only to a typical RACING bicycle. How many of us ride that kind of bike?

Raise your hand if you ride a "racing" bicycle. Doesn't matter if you actually race it. Raises hand... looks around...

Are those watts average for the ride?

Watts normalized, based on IF for the ride.

All the plot proves is that somewhere around a 230-250 watt "effort" (regardless of weight of the rider, bike, pannier, ANYTHING), you're going to be burning ABOUT 40 cal/mi.

It doesn't matter who you are, what bike you ride or what you put on the bike. 230-250 watts normalized (effective effort) is going to do that.

I'm 167 lbs and a pretty fit racer, but a 220 lb unfit cyclist may or may not be expending that same type of energy during their ride, In fact, my 167 lb and 240 watts is roughly 3.2 w/kg. A similar effort for a 220 lb rider will be 310 watts and slightly over 1000 cal/hr. BUT, that 220 lbs on flat/windless roads will only get about 1 kph faster for the 70 watt increase. Assuming wind/slope, they'll probably be going slower - significantly so for the same w/kg.

Anyway, again the plot was absolutely an n=1 example.

The graph is watts vs. velocity, so those things do matter. An individual pushing a heavy weight to speed N will use more watts than a person pushing a lighter weight to that same speed. I will stipulate that an individual pushing 230 - 250 watts is going to burn the same amount of calories regardless of everything else, but I will not concede that all individuals, regardless of their weight and the weight they're pushing, will go the same speed. Since the discussion is Calories/Mile rather than Calories/Watt, my argument holds. Your next to last paragraph supports my argument.

I still do not see any support for the general statement that an individual will consume an average of 35-40 Cal/Mile. You need more data and/or qualification than that. You may make the statement that an individual in reasonable shape on a flat course doing an average of N MPH on a road bike will consume that amount, or you may present a formula, like the power calculator, that can make a general estimate, but to state 35-40 as a "rule," as I've seen done in this forum is, in my opinion, wrong.

Anyway, like I said, take it for what it's worth.


So I was looking at your chart again, and more interesting than the best fit line, is the outliers. What the heck is that data point at 80 cal/mile ?!?

Raise your hand if you ride a "racing" bicycle. Doesn't matter if you actually race it. Raises hand... looks around...

And sees maybe half the people in the room raise their hands. Please don't assume that everyone rides the same type of bike you do, or that they ride under the same conditions or in the same manner you do. Many people, like me, ride ATBs year-round as commuter bikes. I know that my power output varies from day-to-day as road and weather conditions vary. I also know that the number of people I see riding fancy racing style bikes drops drastically when its raining, cold, windy, or any other extreme.

And sees maybe half the people in the room raise their hands. Please don't assume that everyone rides the same type of bike you do, or that they ride under the same conditions or in the same manner you do. Many people, like me, ride ATBs year-round as commuter bikes. I know that my power output varies from day-to-day as road and weather conditions vary. I also know that the number of people I see riding fancy racing style bikes drops drastically when its raining, cold, windy, or any other extreme.

Hey, I wasn't assuming, I was asking. I don't know what mix of people hang out in the t&n forum, but from most of the chatter I've seen over the years I've been hanging out here, most of the people that post are on road bikes. Many of those are "racing bikes", even though I think that most people don't actually race.

The graph is watts vs. velocity, so those things do matter.

Um... no it's not. It's watts vs calories/mile. Speed is not considered anywhere in that chart. It's not even in any of the underlying data.



You need more data and/or qualification than that. You may make the statement that an individual in reasonable shape on a flat course doing an average of N MPH on a road bike will consume that amount

I haven't made that statement, nor can you or anyone. I will make the statement that ANY rider in ANY shape on ANY bike will consume X amount of calories based on output of power. If you ride at less power one day, you probably go slower and cover less distance.

Find me a calorie calculator that does a better job coming close to calorie count than 40 cal/mile and I'll gladly recommend that to folks instead. You probably won't find one - and it certainly won't be any HRM on the market.

Maybe some others will post data from their power information, but the folks I've talked to before have said it's been roughly the same for them.

Calorie consumption is different for everyone. Depends on your weight, height, muscle mass, fitness level. Really fit people will not burn many calories at all due to low heart rate. Usually fit people will have a lower BMR due to them not eating enough for the amount of cardio they do. This results in the body conserving energy. That’s why a lot of top cyclist who are doing 800km/week can hold their weight without eating more then your average person.

The body is an amazing thing and can adapt in so many ways. And your metabolism is something that can shift up or down easily to match your calorie consumption. I've learn't this through personal experience in bodybuilding, being cert 4 qualified and doing much research.

Most of us don't ride racing bikes. Road bikes will have a higher curve. ATBs even higher than that. Add more still if you're carrying a lot of extra weight like panniers with your clothes and lunch, etc.

I had assumed that racing bikes would take the most energy to shove along due to gearing, roadbikes could be geared easier, ATBs the easiest.

I realize my mistake. I was looking at the in-line graph on page 1, not the attached GIF that you'd added to one of your posts. Mae culpa.

However, there is still a problem with your graph. The units on the X axis are not in miles, but in power units. That means that the graph is Cal/Power Unit, not Cal/Mile. We've already agreed that it takes a different amount of effort, depending on a number of independent variables, for any given individual to generate a given unit of power, so extrapolating your graph to Cal/Mi is only valid for you or someone like you under the same conditions you experienced when you created the graph.

Hey, I wasn't assuming, I was asking. I don't know what mix of people hang out in the t&n forum, but from most of the chatter I've seen over the years I've been hanging out here, most of the people that post are on road bikes. Many of those are "racing bikes", even though I think that most people don't actually race.

My apologies then. I hang more in the commuters and winter cycling areas where roadies are not as strongly represented. My personal bike is an hybrid and I use it year-round, covering both roads and dirt on my daily commute.

I had assumed that racing bikes would take the most energy to shove along due to gearing, roadbikes could be geared easier, ATBs the easiest.

As a general rule, ATBs are slower for the same amount of power provided than road bikes. They weigh more, have smaller, wider tires, etc.

I realize my mistake. I was looking at the in-line graph on page 1, not the attached GIF that you'd added to one of your posts. Mae culpa.

However, there is still a problem with your graph. The units on the X axis are not in miles, but in power units. That means that the graph is Cal/Power Unit, not Cal/Mile. We've already agreed that it takes a different amount of effort, depending on a number of independent variables, for any given individual to generate a given unit of power, so extrapolating your graph to Cal/Mi is only valid for you or someone like you under the same conditions you experienced when you created the graph.

You made another mistake, reread nomadvws post.

Calorie consumption is different for everyone. Depends on your weight, height, muscle mass, fitness level. Really fit people will not burn many calories at all due to low heart rate. Usually fit people will have a lower BMR due to them not eating enough for the amount of cardio they do. This results in the body conserving energy. That’s why a lot of top cyclist who are doing 800km/week can hold their weight without eating more then your average person.

The body is an amazing thing and can adapt in so many ways. And your metabolism is something that can shift up or down easily to match your calorie consumption. I've learn't this through personal experience in bodybuilding, being cert 4 qualified and doing much research.

BMR has nothing to do with this; we are talking about calories burned during exercise above normal maintenance values. Metabolic efficiency does not differ much between individuals and very fit people tend to go faster which decreases not increases efficiency.

The approximation is very good and the outliers you may imagine or artificially create is almost certainly due to bad science. For example the OP uses a hill climb example where the sampling period is very short. This demonstrates a lack of understanding of what is considered statistically significant. In general you get an N^0.5 improvement in signal to noise when increasing the number of samples or sampling duration. So if you sampled only say 0.1mile then of course you will get meaningless data.

BMR has nothing to do with this; we are talking about calories burned during exercise above normal maintenance values. Metabolic efficiency does not differ much between individuals and very fit people tend to go faster which decreases not increases efficiency.

The approximation is very good and the outliers you may imagine or artificially create is almost certainly due to bad science. For example the OP uses a hill climb example where the sampling period is very short. This demonstrates a lack of understanding of what is considered statistically significant. In general you get an N^0.5 improvement in signal to noise when increasing the number of samples or sampling duration. So if you sampled only say 0.1mile then of course you will get meaningless data.

actually it does.

The body becomes more efficient as you get fitter this is shown in BMR and also working metabolic consumption. Please i dont go and read study after study. Unlike some, i know this from personal experience. This is widely known in the bodybuilding community. Sure a fitter person goes faster but this does not mean less efficient. The body will adapt to nearly everything, and like i said before, the body will adapt to extreme cardio by slowing BMR and becoming very efficient is calorie consumption. We use these principles to gain and lose weight in bodybuilding.

So going off watts, will be off. Theres no true way to measure calorie expenditure.

actually it does.

The body becomes more efficient as you get fitter this is shown in BMR and also working metabolic consumption. Please i dont go and read study after study. Unlike some, i know this from personal experience. This is widely known in the bodybuilding community. Sure a fitter person goes faster but this does not mean less efficient. The body will adapt to nearly everything, and like i said before, the body will adapt to extreme cardio by slowing BMR and becoming very efficient is calorie consumption. We use these principles to gain and lose weight in bodybuilding.

So going off watts, will be off. Theres no true way to measure calorie expenditure.Yes there IS a way to measure, and measure very accurately calorie expenditure. And that's in an isolation chamber.

Efficiency doesn't relate to turning food-calories into watts, that's fixed at 38-ATP per glucose and every human on Earth is exactly the same for that. The efficiency changes is with oxygen-consumption. The more fit you are, the more oxygen you can extract from the air and more of that oxygen is actually used by the muscles to form more ATP.

Also muscle-efficiency, that is, force-per-oxygen-consumed goes down with increasing leg-forces as well. The closer and closer you get to LT and going anaerobic, the less and less power-increase you get for each additional oxygen-consumed.

Additionally, on the bike, higher-speeds ARE more inefficient. Riding at 25mph consumes about TWICE as many calories/mile as at 15mph. Aside from the increased air drag, I'm sure pedaling form goes out the window as you're mashing bigger gears in squares rather than spinning easy circles. A larger percentage of your muscle-forces will go into directions that don't push you down the road, such as trying to stretch the crank at the bottom of the stroke, or into wobbling your knee and upper-body around.

Yes there IS a way to measure, and measure very accurately calorie expenditure. And that's in an isolation chamber.

Efficiency doesn't relate to turning food-calories into watts, that's fixed at 38-ATP per glucose and every human on Earth is exactly the same for that. The efficiency changes is with oxygen-consumption. The more fit you are, the more oxygen you can extract from the air and more of that oxygen is actually used by the muscles to form more ATP.

Also muscle-efficiency, that is, force-per-oxygen-consumed goes down with increasing leg-forces as well. The closer and closer you get to LT and going anaerobic, the less and less power-increase you get for each additional oxygen-consumed.

Additionally, on the bike, higher-speeds ARE more inefficient. Riding at 25mph consumes about TWICE as many calories/mile as at 15mph. Aside from the increased air drag, I'm sure pedaling form goes out the window as you're mashing bigger gears in squares rather than spinning easy circles. A larger percentage of your muscle-forces will go into directions that don't push you down the road, such as trying to stretch the crank at the bottom of the stroke, or into wobbling your knee and upper-body around.

Isolation tank – never heard of it. I would be very surprised if it did anything truly accurate. Anything to do with the human body and measurements will never be truly accurate (our body is very complex and there are things we still don’t understand – hence no one truly knows what DOMS is from)

You’re missing the point.

The point of this thread was the 40cal/mile. Does everyone burn 40cal per mile? Absolutely not. Calorie expenditure is going to be different for everyone.

What I’m saying is that cyclist will tend to have a low BMR due to all the cycling you do. The body slows down it metabolism (I don’t care how, but it can do this without getting fitter and does it for survival). Cyclist will have a lower BMR due not eating enough for the amount of calorie expenditure – this is how the body will react. People who are fit (cyclist) will tend to burn less calories then a sedentary person doing the same work, eg cycling at 20km/hr for 1 hr.
If the fitter person were cycling at an equivalent intensity eg both at 170bpm I would say the calorie expenditure would be similar if they were of similar weight and similar muscle mass similar height and similar age. I try not to go too deep in my learnings, I prefer to go with what works practically for myself.

The best way to determine how many calories your burning is to look at your diet and determine how many calories your taking in without losing or gaining weight.

So I've been watching and participating in this board a fair amount over the past few months, and I've seen a number of times where people quote that cyclists burn between 35 and 40 calories per mile. I mean, some people almost seem to take that range as gospel. So, I wanted to know where this number came from. Could I find any study or reference to support this claim? If so, what were the suppositions around which the claim was based?



You might want to read this, which I wrote a week or so ago...

http://riderx.info/blogs/riderx/archive/2007/08/08/figuring-calories-per-mile.aspx

Polar will overestimate if the heart rate is not high either. Put on a polar watch for a whole 24hrs and you end up burning a ****load of calories.

Isolation tank – never heard of it. I would be very surprised if it did anything truly accurate. Anything to do with the human body and measurements will never be truly accurate .

The first law of thermodynamics and the science of calorimetry are on solid footing.

You might want to read this, which I wrote a week or so ago...

http://riderx.info/blogs/riderx/archive/2007/08/08/figuring-calories-per-mile.aspx

Uh...I did. I linked to it in the last line of the OP.

Isolation tank – never heard of it. I would be very surprised if it did anything truly accurate. Anything to do with the human body and measurements will never be truly accurate (our body is very complex and there are things we still don’t understand – hence no one truly knows what DOMS is from)

You’re missing the point.

The point of this thread was the 40cal/mile. Does everyone burn 40cal per mile? Absolutely not. Calorie expenditure is going to be different for everyone.

What I’m saying is that cyclist will tend to have a low BMR due to all the cycling you do. The body slows down it metabolism (I don’t care how, but it can do this without getting fitter and does it for survival). Cyclist will have a lower BMR due not eating enough for the amount of calorie expenditure – this is how the body will react. People who are fit (cyclist) will tend to burn less calories then a sedentary person doing the same work, eg cycling at 20km/hr for 1 hr.
If the fitter person were cycling at an equivalent intensity eg both at 170bpm I would say the calorie expenditure would be similar if they were of similar weight and similar muscle mass similar height and similar age. I try not to go too deep in my learnings, I prefer to go with what works practically for myself.

The best way to determine how many calories your burning is to look at your diet and determine how many calories your taking in without losing or gaining weight.

No offense, but you sound pretty ignorant about basic science and physiology. Many of your statements have little to no basis in reality (e.g., "Cyclist will have a lower BMR due not eating enough for the amount of calorie expenditure").

Try reading this Wikipedia article on BMR:
http://en.wikipedia.org/wiki/Basal_metabolic_rate

I do, however, agree with your last sentence. For most people, determining an exact number is less important than finding a way of eating and exercising that results in an appropriate body weight.

The point of this thread was the 40cal/mile. Does everyone burn 40cal per mile? Absolutely not. Calorie expenditure is going to be different for everyone.

The point is not that every cyclist burns exactly 40 cal/mile. Obviously there is variation. I think what we are all saying, is that it is a good rule of thumb.

Yeah.. we could say "hey, you should burn around 40 cal/mile"

Or I could tell everyone "No way to know without a power meter." I certainly cannot tell people to use ANY of the online calculators which I have found to all grossly overestimate calorie expenditure.

Personally, I take my weight every morning after taking the morning piss. Then I plug it into my Excel spreadsheet. I count every calorie I eat, and only "count" calories I put out based on cycling.

The spreadsheet does the following math:
1. Take the last 12 days of "intake" calories, subtract the last 12 days of "output calories" on the bike as determined with a 1:1 kJoule to kCal ratio from the powermeter.

Example: I consumed roughly 51k calories in the last 12 days, and "burned" roughly 22357 calories - resulting in a Net Calorie Consumption of 29039 calories.

2. Take the difference in weight between today and 12 days ago and determined the weight/gain or lost.
Currently ~ -1.7 lbs (I gained 1.7 lbs)

3. Multiple that amount in step 2 by 3500 (for lbs). (3500 cal/lb) = 5950 cal

4. Subtract that from the amount from step 1 - since those 5950 calories are "theoretically" the calories I didn't burn that caused the "weight gain."

5. Divide the resulting amount of 29039 - 5950 = 23089 by 12 to get "calories per day burned not cycling." That says I burn around 1924 cal/day not cycling.

Since I could drink a liter of water before bed and be "heavy" the next day and skew my results, I take the average of the last 12 days of this data. This indicates I burn roughly 2500 calories per day not cycling. With a measured RMR of 2052, that number is essentially "right on."

Or.. you could go get an account at fitday.com and let them do the math. You still don't know the "output" unless you're running a power meter, but I'd be willing to bet it's awfully close to 40 cal/mile for almost anyone. If I reverse all my math using 2500 cal/day burned not cycling, and calculate calories burned cycling based on distances, I get 38.6.

No offense, but you sound pretty ignorant about basic science and physiology. Many of your statements have little to no basis in reality (e.g., "Cyclist will have a lower BMR due not eating enough for the amount of calorie expenditure").

Try reading this Wikipedia article on BMR:
http://en.wikipedia.org/wiki/Basal_metabolic_rate

I do, however, agree with your last sentence. For most people, determining an exact number is less important than finding a way of eating and exercising that results in an appropriate body weight.

My statement may have generalised "Cyclist will have a lower BMR due not eating enough for the amount of calorie expenditure" but it is true. A lot of cyclist, and yes I am part of a cycling club (I suck though :D cause I don’t do enough cycling) and I know and work with a number of cyclist. A cyclist overall weekly calorie expenditure would by high, but their BMR or RMR would be low. Simply due to the body trying to control its weight. Your doesn’t want to lose or gain weight and is always trying to stabilise itself, that’s why people struggle to lose weight and plateau and this goes for gaining weight too.

A few statements from this article which support my argument I’ll point out:

“There are several companies testing the public for the respiratory quotient that identifies heart rates attributed to substrate utilization to assist with weight loss. It is theorized that if a person can more accurately know what amount of energy from carbohydrates, fats and proteins is needed to survive, then a person can select consumption patterns to more efficiently match what is required by the body for daily activities. Thus the emphasis shifts from caloric restriction, which slows the BMR or RMR and causes frustration of weight management goals, to substrate utilization, which focuses on what the body needs to stay healthy”

I don’t think there was anything in there that actually was against me. Though I’d like to point out a couple of things in that article that I thought was interesting:

“What brings interest to the study of basal metabolism or resting metabolism are the paradoxes. For example, there are formulas for prediction which have many contradictory outcomes. If muscle is the principle determinant of resting metabolism, why does metabolic rate go up when we gain weight, including fat, and become weaker physically due to loss of muscle mass from caloric restriction?”

With no scientific background, my personal opinion (and personal experience) is that our metabolism is always changing to stablise our weight. If we don’t eat enough then the body will slow our metabolism down to match the amount of energy coming in. If we eat too much (as we do when trying to gain muscle and unfortunately fat as well.. you got to eat a lot) the body will raise our metabolism to again stabilise our weight. Like I said before the body doesn’t really want to lose and gain weight consistently, if at all (I couldn’t be sure for abese people as they tend to lose weight quickly and consistently) .

“Why do we assume that 2,000 kilocalories daily is the standard amount of energy needed for a woman to survive, and 2,500 for a man, when the basal metabolic rates are so different in all the studies that are performed on this topic each year?”

Well I for one don’t assume that. As I’ve stated before it will be different for everyone. People eat different amounts of food and have different amounts of calorie expenditure. You can use it as a rough starting point and then change to suit for you notice weight gain or loss. In the bodybuilding community we carb cycling and have refeed days to keep metabolic rate under control.

Anyways that’s my ramble. I’m not here to argue with anyone, but this is just my opinion that’s based on real world experience. I really don’t like people telling me how it is from a study they pulled from google, from a writer and scientist I’ve never heard of and possibly has no training experience at all. I use to read all the studies when I first started out, but eventually found that there were too many contradictions and that it was best to do your own experimental work and find out for yourself. Don’t get me wrong some studies have their place.

cheers...