Computing Uphill Calories

Quoted post said:

Originally posted by gntlmn
There must be some kind of rule of thumb for estimating how many extra Calories you burn if you ride uphill rather than on the flats. I found these rules of thumb for estimating energy usage on the flats, but I wonder what the adjustment would be for a hill climb. Like for example, if you know what the rate would be on the flats using these factors here, maybe you can just compute directly the extra calories per foot (or meter) of elevation you climbed, and then just add this on.

MPH: Calories per Mile for a 155 lb (70 kg) average sized man
10: 26
15: 31
20: 38
25: 47
30: 59

This means you burn 26 Calories per mile at 10 mph, but 59 Calories per mile at 30 mph. (1 mph = 1.609 kph)

not sure about the other figures as i've not worked them, but at 59 kcal/mile, and you calculate that out for an hour (59 x 30) = 1770 kcal, then the estimated average power for that would be 492 W, which would be way above current human limits, about 25% too high.

if you want to know your expenditure when climbing you can calculate your potential energy, or your best bet is to go to www.analyticcycling.com and use the calculators there. you'll also be able to better calculate your level ground energy expenditure too. analytic cycling will give you an estimate of your average power, which you should then multiply by 3.6 to get your expenditure per hour.

ric

Not outside human limits. It was calculated that Indurain had to generate just above 500 watts for his 53 km/hr hour record.. However I doubt we will find Indurain 2 here on this board.

The chart undoubtedly calculates for a standard position and standard bike for which air drag is higher than for an elite cyclist using double disc wheels (or deep section front, disc rear), aero frame and an optimized body position, skinsuit and helmet. The chart calculates power required to go at some speed with some drag value and is a rough guide, it has nothing to do with human capabilities.

Analyticcycling is a great site.

[QUOTE]Originally posted by bikeguy
[B]Not outside human limits. It was calculated that Indurain had to generate just above 500 watts for his 53 km/hr hour record.. However I doubt we will find Indurain 2 here on this board.
[/quote]

the figures you quoted were for a 70 kg person, which Indurain wasn't, as he was considerably heavier, and thus, that figure was beyond the limits for someone of that mass.

ric

You didn't specify mass, just that it was outside human limits. :-)

ricstern said:

not sure about the other figures as i've not worked them, but at 59 kcal/mile, and you calculate that out for an hour (59 x 30) = 1770 kcal, then the estimated average power for that would be 492 W, which would be way above current human limits, about 25% too high.

if you want to know your expenditure when climbing you can calculate your potential energy, or your best bet is to go to www.analyticcycling.com and use the calculators there. you'll also be able to better calculate your level ground energy expenditure too. analytic cycling will give you an estimate of your average power, which you should then multiply by 3.6 to get your expenditure per hour.

ric

I knew about that 3.6 factor already after playing with the numbers and doing some reading. But I didn't think to test the outside range for reasonableness.

Aside from considerations of wind resistance and power, which certainly would result in my computing the hill climbing calories after perhaps lengthy calculations and approximations, it seems that there should be a simple rule of thumb for caloric expenditure per kg per meter up a hill, assuming absolutely no wind resistance or rolling resistance. I would like to know what this rule of thumb is because this would be the lower limit of my expenditure, the amount by which my approximations could not fall below. I think if I knew this number, I wouldn't even bother to go into much detail on each ride. It would be interesting to play with the numbers a bit to get a general idea of how much variability there would be under different conditions. Then I could say, "I burned 1000 calories at least, and possibly up to XXXX calories on that climb" just by knowing the elevation gain and the mileage.

My energy conversion table says that one kg-meter=.00234 kcal. So, using Ric's factor of 3.6 for metabolic efficiency, and ignoring friction losses and aero drag, we burn .00843 kcals for every kg-meter climbed.

Take for an example an 80 kg total bike and rider. Every meter climbed would consume .674 kcals. If we are able to climb 900 meters/hour, we would burn 606 kcals.

As a reference, a 900 m/hr vertical rate would be equivalent to riding up an 8% grade at 7 mph, not a bad pace for a club rider. From what I've read, Lance will be climbing at more than double this rate in a few days.

dhk said:

My energy conversion table says that one kg-meter=.00234 kcal. So, using Ric's factor of 3.6 for metabolic efficiency, and ignoring friction losses and aero drag, we burn .00843 kcals for every kg-meter climbed.

Take for an example an 80 kg total bike and rider. Every meter climbed would consume .674 kcals. If we are able to climb 900 meters/hour, we would burn 606 kcals.

As a reference, a 900 m/hr vertical rate would be equivalent to riding up an 8% grade at 7 mph, not a bad pace for a club rider. From what I've read, Lance will be climbing at more than double this rate in a few days.

Your end result sounds reasonable or in the ballpark. I'm not sure about the conversion process, but I'll accept this. And I think you need to include your full weight in this calculation--body, clothes & shoes, bicycle (oh yeah, you mentioned this already). For me, if I climb an 800 meter mountain, it's only going to burn about 550 KCals. That's not much, but at least I won't be convincing myself I'm not eating enough when I should be eating less. 😄

Actually, the steeper the mountain is, the more accurate this rule of thumb is because wind resistance and rolling resistance become a smaller percentage of total work. The climbing becomes the biggest factor.

dhk said:

My energy conversion table says that one kg-meter=.00234 kcal. So, using Ric's factor of 3.6 for metabolic efficiency, and ignoring friction losses and aero drag, we burn .00843 kcals for every kg-meter climbed.

i may be missunderstanding what you've written... but the 3.6 is nothing to do with metabolic efficiency.

to get a ball-park estimate of your energy expenditure, you need to know the "work done", which is equal to power*time. that's power / 1000 and then multiplied by time in secs. there's 3600 secs in an hour, so rather than dividing power by 1000, and then multiplying by 3600, just multiply average power by 3.6 to calculate your approx. energy expenditure.

ric

The devil is in the details 😄 . A joule is the amount of work to lift 102 grams of mass one meter against Earth's gravity. There are 454 grams/lb. Therefore, a 160 lb man will require 160*454/102 = 712 joules of work to gain one meter of elevation. Since a joule = .239 calories, this would be 712/.239 = 150 calories or 0.150 KCalories. An 800 meter hill would require 120 KCals under these assumptions.

Assumptions taken from here http://en.wikipedia.org/wiki/Joule

That's a lousy low end estimate. I figured it would be a good second check on the power estimates, but it doesn't even come close. Maybe the difference is heat loss and mechanical inefficiency (bouncing up and down, etc.). I know it takes a lot more KCals than 120 to power up an 800 meter hill.

The 800 m hill I'm thinking of would probably take about 450 to 750 KCal to climb using power estimates and fudge factors. That's a lot higher than the pure physics approximation above.

It sure seems like a rider should be able to ballpark guess these energy numbers without having to get a power meter, gps, hear rate monitor, etc.

Actually, I'm beginning to wonder whether the actual physics work done (i.e., the measure of energy required to move an inert mass from one elevation to another with no friction) is perhaps that much lower than the biomechanical work done. This would suggest a biomechanical efficiency of something like 25%, which may not be that far off. I think most of the energy goes out in heat loss.

efficiency during cycling is ~ 20 to 25% depending on absolute fitness, and the absolute power that you're riding at (plus other variables, e.g., cadence affects efficiency).

thus, if you've (e.g.) averaged 200 W for 1-hr - you've done 720 kj of work. That's then ~ 172 kcal. However, as cyclists were about 20 - 25% efficient (this can only be calculated in a lab by measuring expired respiratory gases; and is only applicable to the conditions tested). Thus you then need to multiply your kcal (172) by a factor of 4 to 5 to get your ball-park measure of kcal, i.e., 688 to 860 kcal. however, as it's highly unlikely you'll know your actual efficiency, most just recommend swapping the kj for kcal, i.e., just call it 720 kcal. that's about the best ball park figure you can come up with.

ric

ricstern said:

efficiency during cycling is ~ 20 to 25% depending on absolute fitness, and the absolute power that you're riding at (plus other variables, e.g., cadence affects efficiency).

thus, if you've (e.g.) averaged 200 W for 1-hr - you've done 720 kj of work. That's then ~ 172 kcal. However, as cyclists were about 20 - 25% efficient (this can only be calculated in a lab by measuring expired respiratory gases; and is only applicable to the conditions tested). Thus you then need to multiply your kcal (172) by a factor of 4 to 5 to get your ball-park measure of kcal, i.e., 688 to 860 kcal. however, as it's highly unlikely you'll know your actual efficiency, most just recommend swapping the kj for kcal, i.e., just call it 720 kcal. that's about the best ball park figure you can come up with.

ric

Hmmm. That's very interesting. I wonder if that's one of the reasons why a rider like Miguel Indurain in his day, given that his resting metabolism was so low, was able to generate a much higher wattage than most riders. Perhaps his heat loss was lower, his efficiency higher. Maybe his physical work/heat loss ratio was higher than most riders.

his power to mass ratio was similar/same as any other very elite male pro. in fact his power to mass was lower than e.g., chris boardman, who if memory serves me correctly was only about 23 % efficient (i.e., the same efficiency as most racers)

ric

ricstern said:

his power to mass ratio was similar/same as any other very elite male pro. in fact his power to mass was lower than e.g., chris boardman, who if memory serves me correctly was only about 23 % efficient (i.e., the same efficiency as most racers)

ric

Perhaps Indurain's efficiency was in this same range, but that doesn't seem to follow logically from the facts you present. In other words, his efficiency wrt heat loss might have been higher or lower than Boardman or other riders. It is not connected to power to body mass ratio in the sense that if you have an unusual efficiency, it would be evident as a higher or lower power to body mass ratio. After all, you can be way more efficient than all other riders and yet have a way lower power to body mass ratio. All that would mean would be that you don't have to burn much off per calorie consumed per mile at a given pace. It doesn't mean that your power to body mass is greater. The higher your output wattage, certainly the higher will be your heat loss (for the same rider). But this says nothing about the oxygen consumed until you measure it by other means.

I remember watching Miguel climbing on many occasions looking like he wasn't even breaking a sweat and breathing only through his nose. Even a small increase in efficiency will result in a tremendous advantage given the very high ratio of heat loss v. actual work done. For example, a 24% efficiency v. a 23% efficiency in the Tour de France would be a huge difference, especially in the mountains where overheating may be a factor. I wouldn't expect a 50% efficiency, but maybe a little bit higher than other riders given Mig's very slow resting metabolism.

gntlmn said:

Perhaps Indurain's efficiency was in this same range, but that doesn't seem to follow logically from the facts you present.

i never actually mentioned anything to do with Indurain's efficiency, it was you who drew the conclusion that high power and high efficiency were somehow connected in your previous message.

i merely stated that while he had a high absolute power, his power to mass ratio was in fact lower than Boardman's power to mass ratio and that Boardmans efficiency was decidedly average (and then mentioned that i was trying to recall if that latter fact was correct).

Quoted post said:

Even a small increase in efficiency will result in a tremendous advantage given the very high ratio of heat loss v. actual work done. For example, a 24% efficiency v. a 23% efficiency in the Tour de France would be a huge difference, especially in the mountains where overheating may be a factor. I wouldn't expect a 50% efficiency, but maybe a little bit higher than other riders given Mig's very slow resting metabolism.

efficiency is quite similar between trained and elite riders and even untrained sedentary subjects. this is because, the legs are constrained by the pedals and you can only pretty much move them up and down (compared to e.g., running where your legs could wobble all over the show).

Efficiency is related to amount of type I fibres.

ric

ricstern said:

i never actually mentioned anything to do with Indurain's efficiency, it was you who drew the conclusion that high power and high efficiency were somehow connected in your previous message.

i merely stated that while he had a high absolute power, his power to mass ratio was in fact lower than Boardman's power to mass ratio and that Boardmans efficiency was decidedly average (and then mentioned that i was trying to recall if that latter fact was correct).

efficiency is quite similar between trained and elite riders and even untrained sedentary subjects. this is because, the legs are constrained by the pedals and you can only pretty much move them up and down (compared to e.g., running where your legs could wobble all over the show).

Efficiency is related to amount of type I fibres.

ric

You could also make the comment that lactate production and anaerobic threshold are quite similar among elite cyclists. You would confirm this by taking your data among many, many elite riders. At the end of the day, you would be convinced. And then you would measure Lance Armstrong's and discover that it is much lower. That's his big advantage. Perhaps efficiency is Indurain's. It wouldn't have to be much better to be an advantage.

How your legs move affects loss due to motion. But what about internal differences affecting metabolism? For example, some individuals have low thyroid production and thus lower metabolism. I don't think that would be an advantage in cycling, but it illustrates one example where this might be a difference not explained by muscle fibers. Might there be some internal difference in Indurain not related to his motion or muscle fibers which would cause a greater efficiency per speed for him relative to other riders? His brother used to ride, as you know, and he did not have Mig's metabolism. I wonder if this was entirely explained by muscle fiber differences or if there was something else. Endorphin production, for example, dramatically increases O2 uptake. Might he have had a greater endorphin production than other athletes?

who cares about lactate production and how high or low it is? I don't see anyone with McArdles beating an elite rider or even a recreational one.

The main difference between riders is the power that they produce at their body mass, and shape/size.

the difference between Miguel and Prudencia (sp?) will have been their absolute and relative power outputs.

how do you know and how would you measure either of their "metabolism's"?

ric

ricstern said:

who cares about lactate production and how high or low it is? I don't see anyone with McArdles beating an elite rider or even a recreational one.

The main difference between riders is the power that they produce at their body mass, and shape/size.

the difference between Miguel and Prudencia (sp?) will have been their absolute and relative power outputs.

how do you know and how would you measure either of their "metabolism's"?

ric

If you find some way to decrease your appetite (hypnosis, behavior modification, etc), this may not make any measurable difference on your immediate cycling performance. But if, by these changes, you lose 2 kg slowly in one year and then ride again in the Tour de France, the difference might be a whole lot more apparent than it would if you measured it in one day.

Reduced lactate production might not make much difference in your performance today, but in one year, all other things remaining equal (and the diminished lactate NOT the result of a debilitating abnormality, like the enzyme abnormalities of McArdles), you would expect to have a dramatically better level of conditioning. Your muscles would have more easily recovered from rides at anaerobic threshold, where the gains come if you can keep yourself from breaking down.

What I'm saying is that what may be measurable only minutely now may be a big factor in the long run.

How do you measure metabolism? Well, Prudencio is the one that made the comment that Mig's metabolism was simply way out there, not like his own. I don't know how he knew that. Perhaps it was partly because of his very low heart rate which I doubt Prudencio shared. I don't know how you would measure metabolism short of hooking up carbon dioxide measuring instruments to the rider somehow.

I bet when a rider has an out of body experience (endorphin rush) preceeding a huge increase in O2 uptake, something is happening on the cellular level which can be measured by an increase in power output, but I'm not sure if this is actually making the rider more efficient. I'd like to know this answer. I wonder if endorphin levels can be measured. I know the concentration would be very low because ounce per ounce (or ml per ml) they are 1000 times as powerful as morphine.

Indurain and Lemond on many occasions I have heard say that they required a long warm up period. I think it takes a long time to generate endorphins. I wonder about this when I hear a rider making such comments.

That Indurain's metabolism was the same as all other elite riders may be true. I'd like to see the numbers.

gntlmn said:

Reduced lactate production might not make much difference in your performance today, but in one year, all other things remaining equal (and the diminished lactate NOT the result of a debilitating abnormality, like the enzyme abnormalities of McArdles), you would expect to have a dramatically better level of conditioning. Your muscles would have more easily recovered from rides at anaerobic threshold, where the gains come if you can keep yourself from breaking down.

i think you've missed my point. it doesn't matter what your lactate is, all that's important is the power that you can produce for the duration of time the race/event/test/whatever is held over.

lactate, like HR is a dependent variable. it's power that's measured and is the independent variable.

Quoted post said:

How do you measure metabolism? Well, Prudencio is the one that made the comment that Mig's metabolism was simply way out there, not like his own. I don't know how he knew that. Perhaps it was partly because of his very low heart rate which I doubt Prudencio shared. I don't know how you would measure metabolism short of hooking up carbon dioxide measuring instruments to the rider somehow.

assuming you've never spoken with either Indurain about such a subject, and knowing how badly a) that languages are translated by magazines, b) the translator may not have known the exact technical names of a specific test, and c) the Indurains may not have known exactly what was being tested i'm thinking we may not know exactly what was tested or what they were *actually* referring to. my feeling is that, something such as VO2max or LT, or TT power was measured and the exact definition has got lost in the translation.

ric

ricstern said:

i think you've missed my point. it doesn't matter what your lactate is, all that's important is the power that you can produce for the duration of time the race/event/test/whatever is held over.

lactate, like HR is a dependent variable. it's power that's measured and is the independent variable.

ric

But isn't lactate the waste product that produced in greater quantities will result in longer recovery time? Doesn't producing a lower quantity of lactate per unit of power output result in a diminished cost of recovery? In other words, if you work your butt off to the max, but don't produce much lactate, won't it be easier to come back tomorrow and do the same or better? Power will improve if you continue to push yourself harder and harder, given you are not at the limits of your genetic capability and you don't poison yourself with lactate in the process.