Hi,

Whichever way you can go faster will burn more calories, for a given distance.
Into a headwind go as fast as you can, that may involve a lower gear than you think.
Generally most people on a long haul can put out more power and go faster, spinning.

rgds, sreten.

Why do your answers always make so much darn sense?! :D

Yesterday, I did my fastest/best ride ever. You are 100% correct...I definitely burned more calories than when I was 40 lbs. heavier and putzing along at 12MPH and stopping halfway up every hill!

I wonder how much we are guessing? http://www.health.harvard.edu/newswe...activities.htm There do seem to be people that actually measure these things.

Problem there, Bubba; the participants are not necessarily p[utting out the same amounts of power; nor achieving the same performance.

Naturally, it's going to take less energy for 125lb person to pedal that 125 lbs. up a hill, or to propel himself at 20MPH, than for a 200 lb. person to do the same.

This stuff does get a bit complicated! There are really two questions. First, how much power has to be applied to the cranks to go a particular speed. It depends on the headwind, the slope, the rolling resistance of the tires, the aerodynamic resistance of the person and bike, the weight of the person and bike, the roughness of the road and whatever suspension there might be on the bike or in the way the person rides.

The second question is, given that a particular amount of power is being generated at the cranks, what is the rate that calories of food energy are being burned by the person generating that power? What I hear sreten and chasm54 saying is that the rate of food energy burn is proportional to power generated at the crank. That proportionality doesn't depend on a person's overall fitness nor on their particular fitness for cycling. That surprises me a bit - I have identified several ways that fitness ought to improve efficiency, i.e. change the ratio between food energy burn rate and crank power. But my proposed tweaks to efficiency could well be negligible.

Of course, a fit person will be able to burn calories much faster than an unfit person, because they can generate a lot more power at the cranks. This means they can go faster along whatever route... given that all the other factors like weight, headwind, slope, etc. are constant. If a person loses weight, then the same power will let them climb a hill faster. If they get more fit too, then they'll have more power available and they can climb even faster.

If you lose 40 pounds and see that your time on a hilly route has improved, it doesn't mean you are generating more power at the cranks!

Here is one of my hilly routes. I weigh 180 lb, my bike is 40 lb, and I carry about 20 lb of lock, tools, spares, etc. I only average about 10 mph but I bet my power at the cranks isn't too shabby!

http://i140.photobucket.com/albums/r...ps61cfa9df.jpg

Exactly!

I mean, when we start making these comparisons, the variables can be: weight; fitness; performance level; etc. The answer is different depending on whether we're talking about two people of different weights achieving the same performance; or two people of the same weight achieving the same performance....and so forth, with all the variables in between.

I may have burned less calories on my first real ride, when it took me an hour and 20 minutes to do 11 miles (Hills!) than I do riding an hour and 20 minutes now...but I can ride 20 miles in that same :01:20 now. So one really has to be careful to not mix apples and oranges [I hear it can give you nasty farts!], and to specify the parameters...otherwise two people who are saying the same thing could end up arguing, when in reality, they are both sayiong the same things, only assuming different parameters.

[QUOTE=MetalPedaler;15667623]Problem there, Bubba; the participants are not necessarily p[utting out the same amounts of power; nor achieving the same performance.

Naturally, it's going to take less energy for 125lb person to pedal that 125 lbs. up a hill, or to propel himself at 20MPH, than for a 200 lb. person to do the same.[/QUOTE]

So isn't that saying the heavier person has to expend more energy or power for the same work, climbing or speed?
If we research the whole study it listed calories burned by speed as well. Do you have a study we can read that states differently? :D The Harvard Study is used by a lot of fitness people including LivesStrong. Indicating that a heavier person has to work harder and thus does more work to get the same results as a lighter one. Pro bike racers have demonstrated this using power meters on lightweight climbing specialists and heavier sprinters. That is only one way to measure things I guess. when it is done by people trained to measure such things rather that by seat of the pants dynometers. You said, "Yesterday, I did my fastest/best ride ever. You are 100% correct...I definitely burned more calories than when I was 40 lbs. heavier and putzing along at 12MPH and stopping halfway up every hill!" All I said was how can you prove it? Harvard would say to burn the same calories cycling you have to work harder or longer. Are you saying Harvard medical is wrong? Or is this like your estimated 170 percent of your Maximum oxygen uptake?:D Oh and our saying wouldn't be Bubba, it would be Dude.:rolleyes:

[QUOTE=Mobile 155;15668052]Ah, but that's what I mean about the variables: Comparing my 11 mile first ride and my 20 mile ride which took the same amount of time, we are looking at almost a 100% difference in the distance covered. On the latter ride, more work was done, so naturally, more calories were expended- even I was heavier and weaker on the first ride.

I thought "dude" was for skateboarders? ;)

Hi,

Get things straight : a 125 lb rider versus a 200 lb rider same fitness.

The bigger rider has all the advantages if as fit as the smaller rider.

Basic assumption is weight relates to power output so the bigger
rider has more power and less frontal area / power than the
smaller rider, clearly obvious comparing kids and adults.

Bigger wins everywhere except for endurance, you don't see
many sprinters running marathons. AFAIK is actually quite
difficult to build up the bulk of endurance muscles, compared
to twitch, but if you do short sharp hills you too can heavily
muscled legs related to building up the twitch muscle fibres.

rgds, sreten..
.

[QUOTE=MetalPedaler;15668077]Nope, Skate, MTB, Surfing, cycling and terms of astonishment. "Dude, you dropped the hammer on that hill." It can be substituted with Bro and sometimes man. :D

But never with the southern term Bubba. But it is hard to tell how many calories one burns without testing. Otherwise you have to rely on you computer HR monitor and Calorie programs. Most of which give more credit to heavier riders for the same distance of faster riders for the same distance. When programing your Calorie counter for a HR monitor you enter your weight and age. The fitter you get the fewer calories the monitor shows you burned. Same with Cycling computers and programs like Livestrongs diet and exercise, Spark and many others. Here is an example. http://www.healthstatus.com/calculate/cbc

What I meant to say: the "unfit" rider will likely have a higher HR than a "fit" rider. And doesn't a higher HR translate in to greater calorie usage?

For a given person on a given day, a higher heart rate means burning more calories. But comparing two people who are at different fitness level... say they're both at 150 bpm - the fit person would be burning many more calories than the unfit person. Getting fit lets you put out more power, and burn more calories, at any given heart rate.

[QUOTE=Mobile 155;15670085]Hi,

That is because its fundamentally stupid and so are most online calculators.

Not many end up burning less calories as they get fitter, most you burn more.

rgds, sreten.

[QUOTE=sreten;15673108]The funny part is Many medical sites disagree with you and so they use such calculators. And even in your country Harvard is a highly regarded source. And as for you statement "Bigger wins everywhere except for endurance, you don't see
many sprinters running marathons." I have to disagree. It is power to weight. Climbing jerseys hardly ever go to the big guys. Having just finished books on the history of the TDF, Giro d'itaila and Vuelta bigger doesn't win in the high mountains very often except descending. So to most of the cycling world you are in the minority in your opinion that bigger wins everywhere. So like I said I need to see a study supporting your contention that is at least as creditable as Harvard. So I guess we just disagree.:eek:

[QUOTE=Mobile 155;15673161]Hi,

Disagree all you like, but don't imply I'm saying things I'm not. For sprinters in all sports
being bigger helps, (as does a high twitch muscle ratio), as power relates to body weight,
and the higher the body weight the less the drag to power ratio.

Maintainable power output to weight ratio is endurance, (a low twitch muscle ratio helps),
and for serious climbing at relatively low speeds there is little advantage in being big.

Being big is an advantage going downhill, your terminal
velocity freewheeling will be higher than a smaller person.

Endurance is the leveller, and you can't disagree with that,
though you state you do and then contradict yourself.

rgds, sreten.

If you don't know the mathematics a calculator is using,
you have no idea what the numbers it puts out mean.

Welcome to Bike Forums. Sometimes a newbie will ask a question that just explodes with a lot of tangents. You have done exactly that. Whenever I did that three years back, I always felt proud.

I have read a LOT on this subject (I am fat) and I find that 500 calories per hour for "working pretty hard" seems to agree with most of the pundits. So your 1:20 ride probably used about 666 calories. As someone noted above, different monitors and analytic tools give wildly divergent numbers - I consider the number that my Garmin generates is useless. Obviously, as indicated by the responses, there is a lot of variability. As you ride more, you will become more efficient, meaning you burn less calories on the same course at the same speed. But as that happens, you will automatically start riding faster - maybe in two months you will ride your 17.32 mile course in one hour flat, and that would use about 500 calories.

But let me note that some of the people responding are very, very knowledgeable. As you read the answers, note how some people seem to know a little more and respond to challengers with consideration. Those are the people I pay the most attention to.

Congratulations on your riding and good luck with your weight loss. Do everything possible to enjoy your riding - scenic routes, good company (join a cycling club*?), comfortable clothing - so you continue to ride. Quite a number of people say that riding before breakfast burns more calories (I don't know if it's true, but I often do it).


* I joined two clubs the first month I started riding. I learned much faster as a result - what to wear, etiquette, scenic courses, etc. I rode in an organized ride almost every Wednesday (mostly retired riders), Saturday, and Sunday for the first six months.

Here is a perspective from the rowing community:

http://www.atm.ox.ac.uk/rowing/physi...html#section11

This agrees with sreten and chasm54, at least what I hear them saying, i.e. that food calories burned is a simple function of mechanical power out, with no significant difference due to fitness etc.

Of course, how much mechanical power out is required to get your bike to go x mph, that is a whole other question!

First, thanks to you and chasm54 for your replies.

Now, I think I get what you're saying here: that two different riders at very different levels of fitness would burn different a different amount of calories, with the fitter rider burning more. I suppose that would be due to the more fit rider riding at a greater speed than the less fit rider. I suppose this because I presume that the fit rider would have lower HR than the unfit rider if both were traveling at the same speed. If that's what you're saying, then I think it agrees with what my question was suggesting. So, wont an unfit rider will use more calories than a fit rider at 15 mph because (s)he will have a greater HR? If both riders are at 150 bpm, wouldn't the fitter rider likely be traveling at a greater speed than the unfit rider? I don't doubt I'm missing something here; I'm not (nor have) making (made) a claim. I'm just honestly trying to gain some understanding here.

Thanks

[QUOTE=sreten;15673300]Was the medical study in there somewhere and I missed it? :lol: The Harvard Study said there is a difference in energy expended because of power to weight. It takes less energy to move less weight up a hill than it does more weight. Cycling and Racing have proven this for years. Colin Chapman was famous for saying as a engineer, "Adding power makes you faster on the straights. Subtracting weight makes you faster everywhere".

The Mayo Clinic Posted this about calories and weight.
Your body size and composition. "The bodies of people who are larger or have more muscle burn more calories, even at rest."

That is from an engineering and Medical point of view.

Hi,

If they are the same size and weight, going at the same speed, they will burn the same calories.

The unfit rider will have a higher HR, and will have to make more effort to keep up.

If both riders are at the same HR, then the fit rider will be going faster and burning
calories at a higher rate than the unfit rider. Over a given distance, the faster you
do the distance, the more calories it takes. Power output determines speed.

Apprarently Bradley Wiggins going like the clappers over 10 miles averaged 476
watts power output, that is probably about 4 times * the calories I'd use riding
10 miles. At 25% efficiency BW would also be generating 1.5kW of internal
body heat, he'd collapse in a torrent of sweat on a stationary trainer.

rgds, sreten.

* Very rough number. I don't know my power output over 10 miles,
a lot less but it will also take me longer to do it, so the total calories
used difference is somewhat less than the power output difference.

I don't believe this is true. A fit rider has a body that is more efficient than an out of shape at producing the same "power" (remember that the human body is quite inefficient at making power - I've seen numbers around 25%).

That being said, I don't know how big an effect being in shape makes quantitatively.

I believe this is true. Woudln't "more effort" translate into more calories? This statement seems to disagree with your sentence just before.

This is true because of the aerodynamic drag, which goes like speed squared. If all of the resistive forces were linear with speed, it would be the case that the total power output to go a given distance would be equal regardless of speed.

[QUOTE=Mobile 155;15674670]Hi,

That doesn't disagree with anything of what I'm saying.

rgds, sreten.

Hi,

How hard you are trying makes no difference to the calories burned.

There is no mechanism to become more efficient at burning calories.
The chemistry and conversion in a muscle fibre doesn't change.

Plenty of mechanisms to become more effective at burning calories.

Two riders of the same size and weight, one within their limits being
unfit, and the other in cruise mode because they can consistently put
out say double the power, will use the same amount of calories.

Over a decent distance the unfit rider will also run of juice well before
the fit rider, as being fit they have more "gas in the tank", but still
up to that point the calories used will be near identical.

This is assuming things are equal - riding style etc and the unfit
rider is not over exerting himself. If the unfit rider has to get out
of the saddle on hills, or use bursts of "twitch" muscle energy,
he will ending burning somewhat more calories, but not much
if at all over a friendly course. A difficult course would of course
be difficult for an unfit rider to ride smoothly and efficiently.

Still in practice its seems intuitive the fit rider would use less
energy, and he most certainly would "feel" like he has, but
the numbers would not reflect how tired each rider is or
tried after the fact, the numbers would be very similar.

rgds, sreten.

This stuff is confusing. Seems to me that this kind of confusion is why scientists use mathematics to talk about it. It's just too complicated for ordinary language.

Suppose P is power, F is fitness, H is heart rate, and B is rate of calorie burning. I think what sreten is saying, and which seems to agree with the general scientific consensus, is that

B = a * P

The thing is that H is not a simple function of P. Probably we could write

P = H * F

So a fitter person is putting out more power at a given heart rate. The power a person produces goes up as their heart rate goes up.

Putting the two equations together,

B = a * H * F

From this equation, you can see that the calorie burn rate most certainly does depend on fitness and effort. The point though is that however fitness and effort affect calorie burn rate, they affect power output in just the same way. The proportionality between power and burn rate is unaffected.

I still wonder about that strict proportionality & the effect of anaerobic work and inefficient pedaling movement but that is all in the noise anyway. No question about the basic relationships. Bradley Wiggins at 200 Watts has a heart rate that is far slower than me at 200 Watts.

That's almost certainly not true. First, not all energy is going into movement. If somebody feels like they are working harder, they are probably using more calories with non-propulsion muscles (such as heart and lungs) which would mean they're burning more calories.


That isn't obvious to me either. From some random post on the internet:

I'm not claiming this is right (at all), but it is consistent with my understanding: that the human body does become more efficient for a given activity when practiced. I wasn't able to find a convincing answer one way or the other Googling around (and this is not my field of expertise at all).