Calorie intake during endurance rides

[mikedkelly]

When i started, he would insist 200-300 calories every hour.
After a few years with him, I noticed that my zones increased pretty dramatically and asked 'well if im outputting more power, im burning more calories...should i be eating more?'

short answer 'nope. keep eating 200-300 calories every hour.'

his level of expertise? he's coached a few world tour guys

Makes sense. Since you can only digest around 250 cals per hour, if you are riding at tempo or above you will probably burn well above that, so you may as well just eat the max that you can digest and not worry about it. What I would love though, is to have a data field on my Garmin for carb calories, where it estimates how much of my work is coming from my glycogen stores as opposed to fat. Then knowing that I started with 1200 or so internally and adding what I eat, I can get a rough idea of how close I am getting to bonking.

[byron505]

When i started, he would insist 200-300 calories every hour.
After a few years with him, I noticed that my zones increased pretty dramatically and asked 'well if im outputting more power, im burning more calories...should i be eating more?'

short answer 'nope. keep eating 200-300 calories every hour.'

his level of expertise? he's coached a few world tour guys

Makes sense. Since you can only digest around 250 cals per hour, if you are riding at tempo or above you will probably burn well above that, so you may as well just eat the max that you can digest and not worry about it. What I would love though, is to have a data field on my Garmin for carb calories, where it estimates how much of my work is coming from my glycogen stores as opposed to fat. Then knowing that I started with 1200 or so internally and adding what I eat, I can get a rough idea of how close I am getting to bonking.

oh damn - i like that carb estimation idea...although im pretty sure i just try to keep every ride calorie positive with bakery stops.

[KWalker]

I don't see the point in the carb estimation app yet. It should be pretty intuitive honestly. What are you going to do if your ride is say 2800kj but at .65IF? Eat an avocado on your ride? Good luck metabolizing and digesting that.

Eating on a ride over 90min shouldn't change. It is probably the dumbest place you can cut calories. You are likely to put on or retain more bodyfat skipping calories on the bike and eating them later when you could instead just eat a tad less off the bike.

Cycling is energy limited and you're not going to eat your way out of it. Train all you want, eat all you want, but pros are born with larger glycogen reserves as well as better metabolic efficiency whereas us peasants are going to get taxed by spending hours draining glycogen at tempo or above no matter what we do.

[mikedkelly]

I don't see the point in the carb estimation app yet. It should be pretty intuitive honestly. What are you going to do if your ride is say 2800kj but at .65IF? Eat an avocado on your ride? Good luck metabolizing and digesting that.

My theory is that it would come into play during endurance rides. If I am 4 hrs into a 6 hr ride and ate 250 cals each hour, I have approx 2200 cals available in glycogen (1200 + 250*4). If my Garmin says I've done 2100kj, that can be really bad if my heart rate has been at 85%+ for most of the ride. However, if I kept it at 60-70%, 30-40% of that work was metabolized from fat, so a lot of that reserve is still available. Don't get me wrong, this has nothing to do with weight loss - I leave that behind if I am riding more than 90 min. In that case I fuel for the work at hand. I am wanting to use the data to help me decide on how to pace the ride.

[kulivontot]

Again, all these attempts at quantification is meaningless unless you can calibrate per individual. Even then if you change the food you're eating from one gu brand to another there's no guarantee it'll be metabolized the same. A calorie from one food is not processed as the calorie from another.

[KWalker]

I doesn't come into play during endurance rides. What are you going to do to change your underlying physiology? If you've done 2100 kj you aren't going to alter that with what you take in during the ride. You can temporarily change your respiratory quotient through diet, but that comes with implications as well. Also, substrate usage isn't linear and the apps do not take into account environmental variables such as temperature, humidity, nor your actual pre-exercise glycogen concentrations into account. As glycogen is depleted it is used in different amounts (which apps try to account for), but the delta in accuracy is so high it will be a non-factor in your ride.

Chances are you are nowhere near the level of someone that needs to pace their ride by fuel usage. The people that do, like long course ultra or tri dorks usually get a better idea of that by doing lab tests and monitoring response to intake. For them it's never a matter of needing more fat during a ride either.

[mikedkelly]

What are you going to do to change your underlying physiology?

If I catch it early in the ride, I would ride at a pace that lowers my heart rate.

Chances are you are nowhere near the level of someone that needs to pace their ride by fuel usage.

It's actually because of my inexperience that this would be helpful. When I first started riding, I was trying to work up to 50 miles. On my first attempt, I bonked at 35 miles, not even knowing what bonking was. My LBS told me I had to eat 250 cals from a bar, gel, etc per hour, and drink a bottle of water. So I took my bars and tried again only to bonk again at 35 miles. After a bit of reading, I learned about FatMax.



It then occurred to me that riding at a HR of 80-85% of my max and burning 600 cal/hour, even with eating right, I was draining my energy reserves within a few hours. And at a pace of 15 mph, there was no way I would ever be able to make my goal of completing a century. Once I started riding at a pace of 70-75% max HR, I was able to start riding further. With more weight loss, my burn rates went down to 350-400 Cal/hour and I haven't bonked since.

I have no idea if there could be a way to get any kind of accurate measurement on the bike of how you are metabolizing energy, but if you based it on HR similar as shown above and it was only accurate within 10%, even a red flashing field that said "Hey fool, slow down! At this rate you are going to be toast in 90 min or less" would be helpful to know for a long ride.

[KWalker]

You don't understand basic physiology do you? The amount of glycogen you can store is often genetically limited and can be temporarily supercompensated through depletion/loading protocols. The rate at which you deplete it again depends on genetics and diet. Ergo, you trying to train at some magical percentage might use less glycogen at that moment, but it's not going to provide adaptations of any sort. Nor will it necessarily increase anything you are citing above. Your burn rates went down and you haven't bonked, which makes sense since you use less total energy, but the effect of the ride has also changed.

This is really forest for the trees shit for amateurs.

Plus, what *f##k* dipshit rides based on some magical fat burning rate? If you suck too much to do the length and difficulty rides you want to do, this is the worst way to try and do them. You should instead train to be better at not sucking for said rides. It would take a total Fred to not understand that they can't just go hard tempo all ride and somehow ride long distances.

[kulivontot]

Well that's a separate issue. 80% HR is basically threshold which you would not expect to be able to ride indefinitely without a large training volume, independent of on-bike nutrition.
If your goal is weight loss, get off the bike and do some resistance training, it's been shown to be more effective time and time again.
There is value to be gained in studying endurance nutrition, I just caution heavily against trying to overly quantify when it has been proven that there are significant variances across the board.

[mikedkelly]

Well that's a separate issue. 80% HR is basically threshold which you would not expect to be able to ride indefinitely without a large training volume, independent of on-bike nutrition.
If your goal is weight loss, get off the bike and do some resistance training, it's been shown to be more effective time and time again.
There is value to be gained in studying endurance nutrition, I just caution heavily against trying to overly quantify when it has been proven that there are significant variances across the board.

Thanks for the balanced response. My intent is to have a stimulating conversation about mathematically modeling energy burn during a ride and looking for ideas. I work with 6000-factor data models during my day job, so variables come with the territory. I realize that you can not measure or know everything, but the key is that not all of the variables are dependent, and many that are only contribute a small amount of statistical significance to the outcome, so we can either eliminate them or compensate for them in a simpler way. My interest in this is not about weight loss, it's about knowing whether I can predict within a useful amount of accuracy (10% or so) whether one can finish a long or hard ride. I think this would be useful for beginners who have no concept of FTP, tempo, or zones, but are wanting to understand the keys to effective cycling (e.g. Fred). But I have also read about TDF racers and their crews who pay very close attention to nutrition, power, etc and are able to tell on a given ride whether the rider will be able to attack on the final climb, or whether they will bonk half way up. One doesn't necessarily have to understand the details of physiology to create predictive models. Many complex things in nature can be modeled through simple approximations within an acceptable margin of error. It's just a matter of finding correlations between simple patterns and complex ones. So is carb loading, genetics and diet significant? Well if it contributes less than +or- 200 calories to your 2000 kj ride, then in this case no. If it is significant, then instead of trying to get a perfect causal equation, perhaps it can be modeled by correlating something simpler that we can measure on the bike, like heart rate (otherwise known as the dipsh*t magical fat burning rate). Anyways, just hoping for a friendly conversation.

[mikedkelly]

You don't understand basic physiology do you? ... This is really forest for the trees shit for amateurs.

Chill dude - this is a discussion, not a debate. -1 for ad hominem fallacy

[kulivontot]

@mikedkelly,
Fair, the models have some uses and are indeed quite fascinating to me, but I find the practical applications as an amateur athlete to be fairly limited. I think that you can indeed start to generate model based on your own experience, calibrations, and data, but I don't think it is reasonable to take models based on some study with limited participation by populations that don't necessarily represent your personal physiology as is as gospel. You can probably use it as a starting point, and definitely utilize the trends presented, but I think for any individual there will be significant variances that will require lots of data and tweaking. For most of us this anecdotally adjusted over time as training experience, as you figure out what does or does not work for you.
My caution from the start is to try to dissuade amateurs from taking a reductionist approach sports science in terms of assuming the calorie values printed on your Garmin are an exact measurement. Human physiology is very complex and although you can get better and better approximations with newer models and updated technology, it is still a guess based on a standard distribution of limited human trials. One size does not fit all. That said, it is perfectly reasonable to use these models, recommendations, and training techniques combined with experimentation with your own performance to tweak what works for you.

[mikedkelly]

@kulivontot
Well said. It is very likely that the pro teams are using models built from a cohort of one as overfitting is actually intentional in their case. And as you said, I have also found that Garmin numbers are all over the board when you go from GPS to Heart Rate to Power as the input- way more than the 5-10% that they advertise. I use it more to measure consistency from ride to ride than for the actual output value.

[KWalker]

You don't understand basic physiology do you? ... This is really forest for the trees shit for amateurs.

Chill dude - this is a discussion, not a debate. -1 for ad hominem fallacy

Not worked up, but honestly cycling and training for cycling have become WAY too complicated on the interwebs. People literally will read this shit and think it matters. It's confusing at best and doesn't really add information or value. Unless your respiratory quotient is literally piss poor from a sugar-dominant diet, then this is a really convoluted way to not fix a problem that really isn't one to begin with. Quite simply you either need to increase your actual MLSS power/FTP/CP whatever term you want to use, most likely some neuromuscular components, and simple long-term basic aerobic fitness. Using this app to ride in a magical zone won't do it for ya.