My question/point - how do you know? The only way that sugar becomes energy, gets out of the blood into the muscle/organs is insulin. The more sugar you take, the more insulin is required. If not - it sits in your blood stream. How do you know how much insulin you are producing - on the bike?

That's where you're wrong.

https://pubmed.ncbi.nlm.nih.gov/6391198/

Another source, same message

[QUOTE=MinnMan;23332438]That's where you're wrong.

Yup. This was subsequently shown to be due to the Glut1 transporter, which mediates insulin-independent uptake of glucose into various tissues. It's basically why the insulin response to glucose is blunted during, and for a while after, exercise and why you should worry a lot more about Poptarts at breakfast than gels during a ride.

Interesting. Thanks for that. I honestly didn't know...

If it's any comfort to you, that's something that I learned originally.....here. From MoAlpha

More from the interview, this time focusing on fasted training. Please note that this discussion is within the context of professional racing and also applies to folks looking to maximize their performance. As many have pointed out, fasted riding in Z1/2 has worked for many as a way of losing weight.

For a relatively modest outlay, you can test it for yourself in real-time with a blood glucose monitor. Even relatively moderate exercise blunts blood sugar spikes significantly.

One thing to avoid is taking on simple carbs in the hour before starting your workout as that will trigger a spike and subsequent dip in your blood sugar when you least want it. So either eat 3 hours before, so that your blood sugar has returned to fasted level or take on the carbs once you are warmed up during your workout. On a long ride I usually start fuelling after about 30-45 mins on the bike if I need more energy for later in the ride.

I find this to be a challenge because most of my serious endurance rides begin early in the morning. Usually I can only manage an hour between breakfast and getting on the bike. For example, waking at 5:30 AM and eating immediately, getting on the bike at 7. My standard breakfast includes complex carbs and protein.

Thanks. I've got the blood glucose meter and used to test extensively. That is how I know that there is not much better than moderate exercise to control BG's.

My concern was with insulin response. Many people have poor insulin control but never know it, as the docs typically only do front line tests for BG's/AIC - meanwhile their insulin levels can be thru the roof. And that can be a major health concern - a silent one.

I was concerned that heavy sugar intake on the bike, something that I am willing to do for performance when required, may cause high insulin levels. And that doing it often, over long periods may not be a good thing... but now I understand that's not the case.

Me too. At least the protein, fats and complex carbs also blunt the sugar spike by slowing down the sugar release. I do much the same, but I try to eat at least an hour before the start, ideally more. I’ve figured that once you get within an hour then you might as well not bother and wait until after the start.

I think this is the main point of the video, although I can’t remember if he framed it that way.

Not my area and I haven’t read about this for some time, but it might be (surprise!) complicated. Most of the data on exercise are not from people with T2DM. T2DM folks have, IIRC, a different representation of glucose transporters (lower Glut1 expression), which could affect insulin response during exercise—I don’t know. I have also read that some may also have genetic variations affecting the transporter proteins and their function. Even less is known about guys like you who are riding their asses off, or my brother who walks 40 miles a week and goes to the gym religiously, to control the disease. This is a very active area of research, particularly in Europe, so maybe the answers are available, but until they are, I think your cautious approach to fueling is wise.

There is a Continental USA cycling team that is comprised of diabetics that's been riding since circa 2009. I don't know whether they are type I or II, but the website lets you sign up and I assume they'll have pertinent information about both types of diabetes and how to manage it while cycling at both low levels and hard levels.

I think they started out just as Type I, however I think they now also have been demonstrating that Type II diabetics can compete. But that's up to y'all to find out.

https://www.teamnovonordisk.com/

They’re all T1. Pro athletes with T2 are so rare that one has to wonder if what they have is a different disease from the usual thing.

I thought one time they had a cyclist with type II on the roster. Maybe 5 or 6 years ago. There once was some information about it on their website then. But I wasn't going to search and see if any is still there today.

Though I'd agree that Type I info isn't going to help any of the discussion here.

You could certainly be right, but they’re practically nonexistent and there are a bunch of rare and interesting genetic causes of insulin insensitivity that aren’t quite what we’re talking about.

What does that even mean? Pretty much everything is "known to have potential health risks".

Does time play any role in this?

Can somebody burn the same amount of calories per hour in a short (< 2 hours) as in a long (> 4 hours) high-level performance ride? Or, in other words, can somebody maintain the same high-level performance (say, push 400 W, burn roughly 1 500 calories, per hour) in a short or long ride, if nutrition was not the issue?

Unless somebody looks like Vingegaard or other pros, who are at around 5% body-fat, is it necessary to match the calorie deficit entirely with sugar to achieve high-level performance?

Theoretically - yes. If you stay under threshold levels of power, or in Zone 3+/-, and you could mentally stand the suffering & have decent fitness - you could sustain the higher level of effort for 2-3-4-5+ hours. Eventually you will run out of the capacity to fuel the effort. The body typically can burn more than it can process. All of it is trainable to a point, like Vingo and being able to consume and process 100+ grams per hour. Where most of us would end up with some intestinal distress trying to do that without training the body to accept that level of sugar.

And no, the effort is not fueled entirely with sugar. Below threshold levels are a mix of carbs and fat. Zone 2 and below can be entirely fueled by fat energy. And one can train the body to become more efficient at burning fat, allowing you to ride even harder for longer periods. Even Vingo at 5% body fat has 100's of thousands of stored calories from fat. And he trains in ways that help him access that energy.

Adam Yates during the last stage of the Vuelta was probably in Zone 3 for 90%+ of the 4-5 hour duration. Possibly with some time at threshold, and some bursts above threshold. He was burning both fat and sugar in Z3 and is well trained to do that. And he slightly bonked out at the end. He was unable to keep up with nutrition and hydration.

At some point the wheels fall off.

The point is that you wouldn’t be able to even if you tried. Not by a long way.

Incidentally, Vingegaard's low body fat doesn't mean he needs to consume any more calories on a ride than anyone else. However, it probably worried his providers during that putative 12-day ICU stay.

well, no myths here... of course you need carbs
when I ride (train or have a longer ride) I eat 90-100g of carbs (maltodextrin/fructose mix) per 1 hour (once i tried a bit more - I mess up my intake and had a mild headache for 15 mins- hyperglycemia?)
which means HALF A KILO of sugar for just 5-6h ride.

you can't even digest the same amount of carbs that you burn... you are always at the deficit. (If you ride a bit more intense >Z2)
simple math, riding 1h @200W = 720kJ (and this is only Z2 ride for me, for Pogi or Vingegaard it could be Z1 )
efficiency on a bike is 20-25%, let's say 25%, so your body needs 720kJ*4 = 2880kJ to produce 200W for 1h,
in calories: 2880kJ = 688kcal

during longer rides it's almost impossible to "eat too much", as all surplus of calories (if it somehow happens) will be used for recovery after.

and you can digest around 100-120g of carbohydrates per hour, which gives only 400-480kcal
(unless you're on keto diet and eat fat which has 1g=8kcal)


when you ride slower, Z1-Z2, your body can take a lot of energy from fat.

I'm not sure what to make of this as a whole, so lets break it down.

Seems reasonable to me that they can. Do you think otherwise.

I can't. But others can that are at the same level as many pro cyclist. I didn't check your math on the watts to Calories (capital C). I assume it's correct.

Do you know that he is at 5% body fat? Is that important here? So taking his published weight of 58kg or 127.9lbs, he has 6.4 lbs of body fat worth 22,400 Calories. Certainly Jonas is one of the skinny ones. So what. I don't think you'll find that the Tdf is always won by person that has the lowest body fat composition. I believe that many or most of the pro cyclist are higher than 5% body fat. 5% is pretty elite, even for a world tour level cyclist. But that is just IMO.

Well if you read what I've said many times before in many threads including this thread, and have read what others that actually are somewhat of a authority on the subject and what even studies have suggested, one can't really consume enough sugar while on the bike to match their Calorie deficit while cycling at a hard effort.

In my case, I'd get too queasy in the stomach from that much sugar in my stomach while working that hard. And many others do too. I might be behind the times, but even pro cyclists only consume about 120 grams of carbohydrates per hour. Or about 480 Calories per hour. Well short of your 1500 Calories per hour for a person working at your sustained pace stated previously.

I only have about half that much that I consume during a ride. And that is still well below the Calorie expenditure given for that ride by my Garmin or the kilojoules reported by my PM.

​​​​​​​So where do you wish to go with all of this?

Since the way you worded your question can't happen IMO, It might be you really meant to word your question like this.......

​​​​Is it necessary to achieve high-level performance when we ride our bikes?

And the answer to that is no.