How many calories needed per hour?

I am not really sure on how many calories and the like but my coach always claims 7g carbs per KG lean body mass per ride the day before then 30g carb per hour of riding. If you look at most sports drinks they are 30-40g carbs per serve anyway so 1 sports drink as well as water while riding should give you pleanty of fuel for riding.

70g Carbohydrates per hour on the bike...up to 300 Calories.

i found this little website that gives you an idea of what you might burn

http://www.coolnurse.com/calories_burned.htm

jeff828 said:

Does anyone know how many calories are needed per hour to maintain your energy level & not bonk or fatigue? This is for a 4-5hr ride of mostly L3 with L4 & L5 thrown in a bit. I burn about 2000-2500 calories in that time period & usually take in about 500-700 calories, is this enough? I ask this because last weekends 4-1/2hr ride my legs started feeling tired & could feel the burn so I downed 2 gels & 2 fig bars, well about 45min later, legs came back to life, had strength & wasnt tired, what gives? 😕 If I would have consummed that extra amount of calories earlier would I have not had that intial fatigue? That would have been bad in a long race or century, stupid mistake if thats all it would take to prevent it.

There's no way not to run a deficit over the course of a ride of significant length; your gut can only absorb 60-70g of cho / hour; while the caloric burn rate depends on your FT, there's no way a healthy male would be burning less than ~600kcal / hour in level 3. Experiment some, and see how much you can tolerate. FWIW, my feeding protocol for long rides is something like:

1. First 500-900kJ, just water.
2. At this point, I start taking around 110-125 kcals (1/2 of a cliff bar or powerbar, a good-sized slice of bread, etc.) for every 250-300kcals I burn.

For me, this is good enough to get me through 4-6 hours ridden hard (high l2 AP and perhaps low l3 np).

sv650s said:

I am not really sure on how many calories and the like but my coach always claims 7g carbs per KG lean body mass per ride the day before then 30g carb per hour of riding. If you look at most sports drinks they are 30-40g carbs per serve anyway so 1 sports drink as well as water while riding should give you plenty of fuel for riding.

Thanks for your advise.
30g per hour is definitely not enough, unless you are riding maybe L1. I rode Saturday & drank 5 bottles of sport drink.

But to ride 4-5hrs just on 1 bottle per hour of sports drink at a med-hard tempo you will definitly run out of fuel, thats why everybody is taking gels, bananas, any kind of solid food with them.

I think spunout & kmavm got it right, I read somewhere recently that the maximum absorbsion is about 70g per hour.

How many calories would this have roughly?

70g x 4 Cal/g = 280 Cal. A sports drink and a bar every hour.

jeff828 said:

Does anyone know how many calories are needed per hour to maintain your energy level & not bonk or fatigue? This is for a 4-5hr ride of mostly L3 with L4 & L5 thrown in a bit. I burn about 2000-2500 calories in that time period & usually take in about 500-700 calories, is this enough? ....

Are you sure about how much you burn? 2 000 - 2 500 seems a bit low for that intensity & duration. According to my Polar 725 (well, it's an estimate, but anyway) I burn like 700-800 an hour at that intensity (I'm ~65 kg).

Doublebiker said:

Are you sure about how much you burn? 2 000 - 2 500 seems a bit low for that intensity & duration. According to my Polar 725 (well, it's an estimate, but anyway) I burn like 700-800 an hour at that intensity (I'm ~65 kg).

Im just going by what the power tap says, never really payed attention to it until recently. Its says Energy: 2143Kj, is this calories burned or am I mistaken?

KJ output is the work performed. As the human body is 25% efficient (rest lost as heat) and 4 KJ uses 1 K-calorie we cancel out the loss and can approximate that the KJ performed is equal to Calories burned.

jeff828 said:

Im just going by what the power tap says, never really payed attention to it until recently. Its says Energy: 2143Kj, is this calories burned or am I mistaken?

It's not calories but after doing the conversion and accounting for efficiency it's pretty darned close.

Calories burned and their source depend on threshold power so one person pushing 250 watts for an hour may not need to eat much of anything and burn mostly fat, while another may be working almost entirely on glucose and need to replenish nearly every calorie burned to keep up the pace.

mises said:

It's not calories but after doing the conversion and accounting for efficiency it's pretty darned close.

Calories burned and their source depend on threshold power so one person pushing 250 watts for an hour may not need to eat much of anything and burn mostly fat, while another may be working almost entirely on glucose and need to replenish nearly every calorie burned to keep up the pace.

Very good point! 🙂

jeff828 said:

Im just going by what the power tap says, never really payed attention to it until recently. Its says Energy: 2143Kj, is this calories burned or am I mistaken?

2143kJ over, say, 4.5hours gives an average power of about 132W. Is that what you pushed?

mises said:

Calories burned and their source depend on threshold power so one person pushing 250 watts for an hour may not need to eat much of anything and burn mostly fat, while another may be working almost entirely on glucose and need to replenish nearly every calorie burned to keep up the pace.

Well, I'd sure hope nobody tells me that I have to eat in order to do a wimpy 1-hour ride at 250W... 😄

Seriously, at 250W for an hour, you'll probably burn around 800-900kcal total. Most people have about twice that amount of glycogen stored in their muscles under normal conditions (i.e., not starved), readily available for immediate consumption, so any normal healthy adult can do such a ride without "needing" to replenish anything at all.
Plus, we haven't taken into account that you always burn some of your fat while exercising. The rate depends on a lot of things, but burning 200kcal of fat per hour would not be unusual.

Spunout said:

As the human body is 25% efficient (rest lost as heat)

Just to nit-pick, a large part of the missing 75% or so is used to support other systems in your body. You know, stuff like breathing apparatus, cardiovascular system (heart muscle, mostly), even the brain, hopefully :p . Also, depending on how efficient a cyclist you are, you will waste some energy in muscles that do not contribute to power at the wheel (rocking your torso back and forth, moving your arms, etc.). Depending on outside conditions, the amount of energy lost as heat can be relatively small.

Dietmar said:

Just to nit-pick, a large part of the missing 75% or so is used to support other systems in your body. You know, stuff like breathing apparatus, cardiovascular system (heart muscle, mostly), even the brain, hopefully :p . Also, depending on how efficient a cyclist you are, you will waste some energy in muscles that do not contribute to power at the wheel (rocking your torso back and forth, moving your arms, etc.). Depending on outside conditions, the amount of energy lost as heat can be relatively small.

I don't believe this is correct.

Your power measuring device is only capturing the energy required to turn the cranks. Muscle itself is only about 25% efficient in converting chemical energy to mechanical energy, with most of the rest lost as heat. Hence the typical conversion of Kj to Kcal.

Those other factors you mention would contribute to additional calories burned but I can't see how your power measuring device would capture any of them.

Finally I don't believe your last statement is correct either. I don't believe external conditions affect the efficieny of muscle to such a large extent that the "amount of energy lost as heat" would be small. The whole system may not have to take action to prevent hyperthermia when it's cold out but that's not because the muscle has become more efficient and is giving off less heat.

"Just to nit-pick, a large part of the missing 75% or so is used to support other systems in your body."

I don't believe that is correct. Muscle is only about 25% efficient in converting the chemical energy to mechanical work is where 75% is loss, mostly as heat. So you can figure it takes 4 times as many calories than your power-measuring device says it does to turn the cranks.

"You know, stuff like breathing apparatus, cardiovascular system (heart muscle, mostly), even the brain, hopefully :p . Also, depending on how efficient a cyclist you are, you will waste some energy in muscles that do not contribute to power at the wheel (rocking your torso back and forth, moving your arms, etc.)."

Sure, but these additional calories wouldn't be captured in your power-measuring devices numbers nor do they have anything to do with the 75% of the chemical energy that is loss when you figure out the calories required to produce that measured power.

"Depending on outside conditions, the amount of energy lost as heat can be relatively small."

Again, I don't believe this to be the case. The efficiency of muscle may be affected by temperature but I hardly think the 75% that is typically "wasted" would be so reduced to the point that it would be relatively small. What outside conditions exactly are you referring to?

Dietmar said:

Well, I'd sure hope nobody tells me that I have to eat in order to do a wimpy 1-hour ride at 250W... 😄

Seriously, at 250W for an hour, you'll probably burn around 800-900kcal total. Most people have about twice that amount of glycogen stored in their muscles under normal conditions (i.e., not starved), readily available for immediate consumption, so any normal healthy adult can do such a ride without "needing" to replenish anything at all.
Plus, we haven't taken into account that you always burn some of your fat while exercising. The rate depends on a lot of things, but burning 200kcal of fat per hour would not be unusual.

You have about 2000cal stored, so your right, doing a 1hr ride at 250watts (900kcal) does not require you to eat, but if you went out 2-3hrs with the club ride you have to take in account all those surges, 500,800,1100watts, pounding your buddies on the hills, sprinting, attacking, etc, that sure is draining that glycogen quite faster, even if you only avreraged 150watts, wouldnt you agree.

"2143kJ over, say, 4.5hours gives an average power of about 132W. Is that what you pushed?"
Sounds pretty close, this was just a steady tempo day, is this too low do you think?

Check out these TDF averages from stage 2, and these guys were racing
http://www.srmdataserver.de/tele/science/telemetry/races.php

Christian Vandevelde ave191watts for 5:47min
Beat Zberg ave199watts for 5:53
Filippo Pozzato ave179watts for 6:03

Check out the rest of the races

Dietmar said:

2143kJ over, say, 4.5hours gives an average power of about 132W. Is that what you pushed?

Just checked, ave 140watts

2 weeks before rode tempo at front all day for 4hrs (70mi) 2216kj, 158watts ave

jeff828 said:

You have about 2000cal stored, so your right, doing a 1hr ride at 250watts (900kcal) does not require you to eat, but if you went out 2-3hrs with the club ride you have to take in account all those surges, 500,800,1100watts, pounding your buddies on the hills, sprinting, attacking, etc, that sure is draining that glycogen quite faster, even if you only avreraged 150watts, wouldnt you agree.

"2143kJ over, say, 4.5hours gives an average power of about 132W. Is that what you pushed?"
Sounds pretty close, this was just a steady tempo day, is this too low do you think?

Check out these TDF averages from stage 2, and these guys were racing
http://www.srmdataserver.de/tele/science/telemetry/races.php

Christian Vandevelde ave191watts for 5:47min
Beat Zberg ave199watts for 5:53
Filippo Pozzato ave179watts for 6:03

Check out the rest of the races

Looks like they were taking it easy. my 2 solo rides this week..

3hour 13min ride avg209w NP 226w 2416KJ
4hour 20min ride avg 198w NP215w 3079kj