How many calories does cycling actually burn?

Pokerface

Alex_Simmons/RST wrote:

Homer J wrote:

So if a pro rode for an hour say at 150 watts with ave heart rate at 110bpm and i did the same ride but my heart rate would be 140bpm, would that mean i've burnt more cals?? :?

If you both rode at 150 watts, then you would have burned the same amount of energy irrespective of your heart rate, provided you both have the same gross efficiency level (which as I have said before can vary from ~ 19-24% between individuals but pros, on average, are no more efficient than ordinary cyclists).

I understand the formula that you get your results from.

However - is there not much more going on in the body than the straight transfer of energy needed to produce the 150 watts for one hour?

For instance - if one rider is going uphill - and spending more time out of the saddle and therefore using his upper body more - will this not use more energy than the other rider than might be sat comfortably, riding on the flat?

Do metabolic rates come into play at all?

Other factors in riding style/position?

fuzzynavel

Pokerface wrote:

Alex_Simmons/RST wrote:

Homer J wrote:

So if a pro rode for an hour say at 150 watts with ave heart rate at 110bpm and i did the same ride but my heart rate would be 140bpm, would that mean i've burnt more cals?? :?

If you both rode at 150 watts, then you would have burned the same amount of energy irrespective of your heart rate, provided you both have the same gross efficiency level (which as I have said before can vary from ~ 19-24% between individuals but pros, on average, are no more efficient than ordinary cyclists).

I understand the formula that you get your results from.

However - is there not much more going on in the body than the straight transfer of energy needed to produce the 150 watts for one hour?

For instance - if one rider is going uphill - and spending more time out of the saddle and therefore using his upper body more - will this not use more energy than the other rider than might be sat comfortably, riding on the flat?

Do metabolic rates come into play at all?

Other factors in riding style/position?

From what I can tell....150 watts (in Alex's example) is the work through the pedals....obviously if you have a different style or maybe wave your arms around like a loon while riding then there will be slight variations but your power through the pedals will still be 150 watts

Chaz.Harding

If you go out hard, you will burn calories at a higher rate. Not nessecerily more. On the cross-trainer ski-thingy in my gym, I can burn over 1500 calories in ONE HOUR!!!

On the Highclere sportive, I burned over 6200 calories in 7 hours. so around 800 is right for me.

Alex_Simmons/RST

Pokerface wrote:

I understand the formula that you get your results from.

However - is there not much more going on in the body than the straight transfer of energy needed to produce the 150 watts for one hour?

Yes, the energy not used to propel the bike is mostly dissipated as heat. Hence the efficiency level.

Pokerface wrote:

For instance - if one rider is going uphill - and spending more time out of the saddle and therefore using his upper body more - will this not use more energy than the other rider than might be sat comfortably, riding on the flat?

At the same power? No.

Pokerface wrote:

Do metabolic rates come into play at all?

Do you mean base metabolic rate? Of course base metabolic rate needs to be considered but it is about an order of magnitude lower than the energy metabolised when riding hard (and is where we talk about differences in delta and gross efficiency). Base metabolic rate mostly needs to be considered when looking at the overall daily calorie requirement/consumption, less so when considering just the time on a bike.

Pokerface wrote:

Other factors in riding style/position?

Might impact performance, but not efficiency. if you go slower, you take longer, so the total energy demand sort of evens out, though not exactly since there is a curvelinear relationship between speed and power.

e.g. same rider riding same 40km course at i. 300W and ii. 310W (3.3% more power):

i. takes 1 hour exactly = 1,080kJ
ii. takes only 59:16 (1.2% less time) but at 3.3% higher power = 1,102kJ or 2% more energy expended over same distance.

Pokerface

Alex_Simmons/RST wrote:

Pokerface wrote:

For instance - if one rider is going uphill - and spending more time out of the saddle and therefore using his upper body more - will this not use more energy than the other rider than might be sat comfortably, riding on the flat?

At the same power? No.

So you're telling me that a power meter can measures the complete output of every muscle group in the body, all at once. 150 watts generated on the readout takes into account upper and lower body output - and not just what is being put through the pedals? Or what is being put through the pedals IS the sum of total physical effort of all muscle groups?

In short - is 150 watts on the meter an absolute number taking into account all factors?

Alex_Simmons/RST

Well the only reason one gets out of the saddle is to produce power at the crank. All using the upper body does is to provide useful leverage for that task. Unless you are doing something else, like power knitting or some such other exercise while riding that doesn't involve turning the cranks.

But if using upper body enables you to produce more power than when seated, then of course you'll use more energy (since by definition you are producing more power).

Infamous

Alex_Simmons/RST wrote:

Well the only reason one gets out of the saddle is to produce power at the crank. All using the upper body does is to provide useful leverage for that task. Unless you are doing something else, like power knitting or some such other exercise while riding that doesn't involve turning the cranks.

But if using upper body enables you to produce more power than when seated, then of course you'll use more energy (since by definition you are producing more power).

Ah, but we are constantly told that standing up to climb is less efficient, is this true then? Or is it more misuse of the word efficient ?

Alex_Simmons/RST

Infamous wrote:

Alex_Simmons/RST wrote:

Well the only reason one gets out of the saddle is to produce power at the crank. All using the upper body does is to provide useful leverage for that task. Unless you are doing something else, like power knitting or some such other exercise while riding that doesn't involve turning the cranks.

But if using upper body enables you to produce more power than when seated, then of course you'll use more energy (since by definition you are producing more power).

Ah, but we are constantly told that standing up to climb is less efficient, is this true then? Or is it more misuse of the word efficient ?

Could be either (wrong use of term or actually less efficient). I've never seen an efficiency analysis of climbing out of saddle. Can't imagine it'd be all that much different though, certainly not enough to change the total calorie count by much.

Infamous

So presumably more to do with pacing than efficiency?

peanut

last winter i used the exercise bikes and spinning bikes in my local gym. 40 mins intense exercise with equivalent perceived effort to hilly cycling 150bpm + gave approx 275-325 calories burnt which is not a lot. Its definitely nowhere near 1000 cals per hour or i would be losing a few pounds every week

Alex_Simmons/RST

Infamous wrote:

So presumably more to do with pacing than efficiency?

Sorry, you've lost me. What's presumably more to with pacing than efficiency?

Infamous

Alex_Simmons/RST wrote:

Infamous wrote:

So presumably more to do with pacing than efficiency?

Sorry, you've lost me. What's presumably more to with pacing than efficiency?

The fact we are told that standing is less efficient.

More about not going too hard rather than being efficient.

Alex_Simmons/RST

Infamous wrote:

Alex_Simmons/RST wrote:

Infamous wrote:

So presumably more to do with pacing than efficiency?

Sorry, you've lost me. What's presumably more to with pacing than efficiency?

The fact we are told that standing is less efficient.

More about not going too hard rather than being efficient.

Ah, OK, yeah that's quite possibly the case. Pacing long climbs is pretty helpful if you want to get up in the shortest time, although some do like to spend substantial time out of saddle, they can still moderate their effort.

simon_says

The calories "burned" _can_ be calculated as follows;

If you ride for an hour producing 3 W/kg and you weigh 75 kg that's 225 W of useful power which for a cadence of 92 rpm (9.63 rad/s) corresponds to _overall_ torque of 23.35 Nm. Power is the dot product of angular velocity (rotational speed) and torque, I've just rearranged for torque which is a vector technically but that's not important.

One Watt is one Joule per second so if you multiply the "useful" power by time you get "useful" energy, so in this case that's 0.81 MJ (Mega-Joules).

Now the process of taking our macronutrients (mainly carbohydrates, fat and protein) into the "molecular units of currency" as far as our bodies are concerned (e.g. adenosine-5-triphosphate ATP from carbohydrates) is a process by which low grade energy (thermodynamic parlance for largely useless energy) is created in high quantities. I've seen this process of dietary chemical energy to kinetic energy and the kinematics of cycling combined with an array of other efficiency depleting (non-isentropic processes) being regarded as a 22% efficient process therefore, to finish the calculation quickly, results in a metabolic/chemical burning of 3.68 MJ of energy (0.81/22%) over that hour. That's the final answer in energy but since the buzz-word is Calories (= 1 kcal) you may divide by the heat capacity of water which you can take as 4180 J/K so 881 kcals is the predicted burn at this power.

Back to the debate about heart rate and power. Is a power reading the only thing that matters for correlating to Calories burned? Well yes, assuming you lock the efficiency at 22% say. However, your heart rate will allow you to determine which zone you are in, e.g. if you're in an anaerobic region your useful power might be higher but your efficiency will plummet and hence your fuel mileage, let's say, is awful. Also your heart rate can provide an indication (and perhaps that's all) of what macronutrient(s) you are metabolizing.

The best bang for your buck is high power at a low calorific rate. I have my own model/ideas for my performance and I could hack up my own software for post-processing logged data quite easily but doing it live with the right kind of hardware would be difficult, need to think about this some more!

Alex_Simmons/RST

simon_says wrote:

The calories "burned" _can_ be calculated as follows;

If you ride for an hour producing 3 W/kg and you weigh 75 kg that's 225 W of useful power which for a cadence of 92 rpm (9.63 rad/s) corresponds to _overall_ torque of 23.35 Nm. Power is the dot product of angular velocity (rotational speed) and torque, I've just rearranged for torque which is a vector technically but that's not important.

One Watt is one Joule per second so if you multiply the "useful" power by time you get "useful" energy, so in this case that's 0.81 MJ (Mega-Joules).

Now the process of taking our macronutrients (mainly carbohydrates, fat and protein) into the "molecular units of currency" as far as our bodies are concerned (e.g. adenosine-5-triphosphate ATP from carbohydrates) is a process by which low grade energy (thermodynamic parlance for largely useless energy) is created in high quantities. I've seen this process of dietary chemical energy to kinetic energy and the kinematics of cycling combined with an array of other efficiency depleting (non-isentropic processes) being regarded as a 22% efficient process therefore, to finish the calculation quickly, results in a metabolic/chemical burning of 3.68 MJ of energy (0.81/22%) over that hour. That's the final answer in energy but since the buzz-word is Calories (= 1 kcal) you may divide by the heat capacity of water which you can take as 4180 J/K so 881 kcals is the predicted burn at this power.

Back to the debate about heart rate and power. Is a power reading the only thing that matters for correlating to Calories burned? Well yes, assuming you lock the efficiency at 22% say. However, your heart rate will allow you to determine which zone you are in, e.g. if you're in an anaerobic region your useful power might be higher but your efficiency will plummet and hence your fuel mileage, let's say, is awful. Also your heart rate can provide an indication (and perhaps that's all) of what macronutrient(s) you are metabolizing.

The best bang for your buck is high power at a low calorific rate. I have my own model/ideas for my performance and I could hack up my own software for post-processing logged data quite easily but doing it live with the right kind of hardware would be difficult, need to think about this some more!

I don't think I've read so many red herrings in one go before. :shock:

simon_says

Alex_Simmons/RST wrote:

simon_says wrote:

The calories "burned" _can_ be calculated as follows;

If you ride for an hour producing 3 W/kg and you weigh 75 kg that's 225 W of useful power which for a cadence of 92 rpm (9.63 rad/s) corresponds to _overall_ torque of 23.35 Nm. Power is the dot product of angular velocity (rotational speed) and torque, I've just rearranged for torque which is a vector technically but that's not important.

One Watt is one Joule per second so if you multiply the "useful" power by time you get "useful" energy, so in this case that's 0.81 MJ (Mega-Joules).

Now the process of taking our macronutrients (mainly carbohydrates, fat and protein) into the "molecular units of currency" as far as our bodies are concerned (e.g. adenosine-5-triphosphate ATP from carbohydrates) is a process by which low grade energy (thermodynamic parlance for largely useless energy) is created in high quantities. I've seen this process of dietary chemical energy to kinetic energy and the kinematics of cycling combined with an array of other efficiency depleting (non-isentropic processes) being regarded as a 22% efficient process therefore, to finish the calculation quickly, results in a metabolic/chemical burning of 3.68 MJ of energy (0.81/22%) over that hour. That's the final answer in energy but since the buzz-word is Calories (= 1 kcal) you may divide by the heat capacity of water which you can take as 4180 J/K so 881 kcals is the predicted burn at this power.

Back to the debate about heart rate and power. Is a power reading the only thing that matters for correlating to Calories burned? Well yes, assuming you lock the efficiency at 22% say. However, your heart rate will allow you to determine which zone you are in, e.g. if you're in an anaerobic region your useful power might be higher but your efficiency will plummet and hence your fuel mileage, let's say, is awful. Also your heart rate can provide an indication (and perhaps that's all) of what macronutrient(s) you are metabolizing.

The best bang for your buck is high power at a low calorific rate. I have my own model/ideas for my performance and I could hack up my own software for post-processing logged data quite easily but doing it live with the right kind of hardware would be difficult, need to think about this some more!

I don't think I've read so many red herrings in one go before. :shock:

Fair point but I did try and go through it in as much detail as possible and state where all the assumptions come from.

Basically if you lock the mechanical efficiency at 22% the useful power and calories burned can be read as the same thing. This is an artifact of the analytical method, but not what is happening in reality. Measuring the power directly and dynamically adjusting for the mechanical efficiency with respect to heart rate is how I would calculate the calories burned.

Alex_Simmons/RST

No, it really is full of red herrings.

simon_says

Alex_Simmons/RST wrote:

No, it really is full of red herrings.

Are you saying efficiency is fixed and is purely a genetic/natural state? It's not a function of anything? I apologise for the engineering terminology, I'm an aerodynamicist.

My advice to everyone is track your W/bpm particularly if you're looking to improve endurance - practice aerobic conditioning and improve oxygen delivery to your muscles because in the absence of oxygen your metabolic efficiency is depleted.



I've added an image from wikipedia, most of you will have seen something like it, just to demonstrate one representation of the metabolic processes that occur (generically) with respect to heart rate. Something to note is that due to the nature of heart rhythm regulation the initial exercise phase can be very inefficient due to lack of oxygen delivery (anaerobic) but your W/bpm would be very high in this transient phase.

Alex_Simmons/RST

simon_says wrote:

Are you saying efficiency is fixed and is purely a genetic/natural state?

No.

simon_says wrote:

It's not a function of anything?

No.

simon_says wrote:

My advice to everyone is track your W/bpm particularly if you're looking to improve endurance - practice aerobic conditioning and improve oxygen delivery to your muscles because in the absence of oxygen your metabolic efficiency is depleted.

My advice would be to focus on improving sustainable power and to toss your HR strap*. It's how much power you can sustain that's important, not what your W/bpm is.

Since we can only sustain an anaerobic effort for a very short time, any concern about anaerobic metabolism significantly lowering our overall efficiency on a ride of any reasonable duration is a red herring. It's an aerobic sport, damn it! - A. Coggan

* unless of course you only have a HR monitor and no power meter, then HR is one guide to intensity that can be reasonably helpful in training.

Alex_Simmons/RST

simon_says wrote:

I've added an image from wikipedia, most of you will have seen something like it, just to demonstrate one representation of the metabolic processes that occur (generically) with respect to heart rate.

Metabolic processes and (more interstingly) the adaptations that occur are better expressed in terms of percentages of our aerobic power, either power at lactate threshold, TT (Functional Threshold) power or Maximal Aerobic Power. Here's an item from my blog on that:

http://alex-cycle.blogspot.com/2008/01/ ... ining.html

simon_says

Thanks for pointing me towards your blog, it'll make interesting reading but watching TdF this minute. You're absolutely right to say that power is extremely important and of course there's no point aiming for the ultimate W/bpm and only pulling a wimpish Wattage.

It's a predominantly aerobic sport for professionals but we are all governed by the same physical laws and whilst professionals may not have to concern themselves with expensive metabolic processes those on the path may not have this luxury of ignorance.

I certainly recommend to those "on the path" to invest in a heart rate monitor, better than nothing, and do the usual stuff; have a look at your averages for consistent effort, check your rest heart rate every now and then etc.

You're obviously passionate about the sport and I have respect, don't want to get too locked into an argument.

Alex_Simmons/RST

simon_says wrote:

It's a predominantly aerobic sport for professionals but we are all governed by the same physical laws ...

It's an aerobic sport for all of us, not just professionals.

simon_says wrote:

... and whilst professionals may not have to concern themselves with expensive metabolic processes ...

What's an "expensive metabolic process"?

simon_says wrote:

... those on the path may not have this luxury of ignorance.

Being ignorant doesn't change the facts about our physiology. It is still an aerobic sport no matter what our level of knowledge of the underlying physiological processes.

However I agree that being ignorant of the facts can make for poor training decisions. This applies equally to professionals as much to the rest of us mere mortal bike riders.

simon_says wrote:

You're obviously passionate about the sport and I have respect, don't want to get too locked into an argument.

Yes I am passionate about the sport but in keeping with your theme, my passion is not relevant either to the topics under discussion (cycling efficiency, metabolic processes, power, heart rates, calculation of energy expenditure when riding a bicycle etc etc).

"My passion" is just another red herring, and perhaps a veiled ad hominem.

Since you have used wiki to look up stuff, here's a wiki definition of a red herring and ad hominem:
http://en.wikipedia.org/wiki/Red_herring_(idiom)
http://en.wikipedia.org/wiki/Ad_hominem

simon_says

Alex_Simmons/RST wrote:

simon_says wrote:

It's a predominantly aerobic sport for professionals but we are all governed by the same physical laws ...

It's an aerobic sport for all of us, not just professionals.

simon_says wrote:

... and whilst professionals may not have to concern themselves with expensive metabolic processes ...

What's an "expensive metabolic process"?

simon_says wrote:

... those on the path may not have this luxury of ignorance.

Being ignorant doesn't change the facts about our physiology. It is still an aerobic sport no matter what our level of knowledge of the underlying physiological processes.

However I agree that being ignorant of the facts can make for poor training decisions. This applies equally to professionals as much to the rest of us mere mortal bike riders.

simon_says wrote:

You're obviously passionate about the sport and I have respect, don't want to get too locked into an argument.

Yes I am passionate about the sport but in keeping with your theme, my passion is not relevant either to the topics under discussion (cycling efficiency, metabolic processes, power, heart rates, calculation of energy expenditure when riding a bicycle etc etc).

"My passion" is just another red herring, and perhaps a veiled ad hominem.

Since you have used wiki to look up stuff, here's a wiki definition of a red herring and ad hominem:
http://en.wikipedia.org/wiki/Red_herring_(idiom)
http://en.wikipedia.org/wiki/Ad_hominem

I've had enough dude, you know what I mean. You admitted the presence of anaerobic metabolism and therefore my ambition in this mild argument has been achieved. End of.