I mean, what is the alternative? I am very conscious of the negative effect of my sugar/malto mix drinks on my dental hygiene, I (almost) always take a swish of regular water of a sip of mix-drink. What more can we do in that regard?
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I can’t answer any of that directly but insulin sensitivity is far higher during exercise so logically that wouldn’t really be a concern anyway
I cannot answer that for you, personally I realize I am not a pro so I limit sugar intake to only 3h+ faster rides
Only if you were burning 100% carbs at tempo effort which sounds unlikely. See below approx 60g from fat or 450 calories available from your body’s fat stores. Plus much higher fat utilisation has been seen in ultra endurance athletes, nearer 120g an hour.
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We already know there are negative effects of long term low carb / keto diet, including several types heart issues like fibrosis and arrythmia, lowered metabolic rate, negative hormonal profile, insulin insensitivity, just to name a few. We also know the body can store a LOT of glycogen, multiple hundreds of grams, and uses glycogen for fuel at a high rate when training. I believe there are more issues with not enough carbohydrate for the trained endurance athlete than eating too many, and more issues (like cancer, metabolic disease, obesity, NAFLD, diabetes, sleep disorders, anxiety) caused by poor nutrition in general (IE low carb / keto, intermittent fasting, chronic low calorie intake or restriction, standard american diet consisting of highly processed industrial food-like substances, low intake of quality foods) than simply fueling with easily digestible sources of carbs while training.
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Like what?
Most of these “long term impacts of high CHO fueling” scary headlines never offer anything other than a suggestion that it might be detrimental to your health, and they’re usually selling some alternative. Selling being the operative word.
Your body is literally designed to create ATP using exogenous sugar and stored glycogen. It’s not as efficient as some other means (oxidative phosphorylation - guess what, still needs glucose!), but by providing the glucose your body needs exogenously you’re supporting a naturally occurring function.
If you’re OVERDOING IT, like 100g of carbs for a 1-hr ride followed by a massive 500cal recovery drink… then yeah, probably a concern in terms of diabetic response. Which is why you should be intelligently making decisions based on fueling needs instead of one-size-fits-every-workout decision making.
Fuel the work.
Also, brush your teeth and don’t forget to drink plain old water while riding too.
There is some context you need to put with that graph, as it is not representative of a typical endurance athlete. Generally over LT2 fat utilization is very low, and in this graph even well above 4mmol lactate it shows nearly 50% fat utilization. Not even world tour cyclists are doing this, and I don’t even know how possible this is without severe carbohydrate restriction, and I don’t believe this is state most people should strive to reach, nor is it optimal for most high level athletes.
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From those who participate in Ironman tris or ultra distance and fairly typical measurements from those who are top 10.
Yes without severe carbohydrate restriction
I think you’ve gone in a few educational levels low here - but that’s cool I gave no reason not to. I’m not looking to solve all of my problems with a crash diet, go keto or otherwise. I happily eat a varied, high quality, high protein, omnivorous diet on a 14/10 and fuel the work that needs fuelling.
I just can’t help but worry that the body’s response to exogenous inputs might, as it is in every other pathophysiology I have studied, be more complex than just the tca cycle or the production of electron carriers.
I agree with @lee82 that the majority of the impact we see in studies relates to the pathological impacts of excess adipose deposition (including tissue hypoxia, metabolic dysfunction, insulin resistance etc). Metabolically active adipose tissue is pro-inflammatory, and nobody needs more cytokines.
But what about neurological pruning? HPA / Cortisol dysfunction leading to epigenetic damage not explained by adipose deposition? Changes to the dopaminergic system? Increases in intestinal bacterial overgrowth leading to increased tnf-a? Macrophage sensitisation?
These are a small part of the many things that are coming out of research into the harmful impact of excess glucose in the body. These studies are almost always done in the presence of excess adiposity and a lack of athletic fitness and training - I just suppose I’m not quite so quick to jump to “Well, GLUT-4 Transporters are on so that excess glucose is going to be magically isolated in my working muscles and nowhere else” (because as I said - that hasn’t been the impression I get about any other intervention in the human body).
I’m not magically going to throw out all of my beta fuel, I just wondered if there was any research going on about this (aka looking at biomarkers in specifically athletic populations) - but so far all I’ve found is that one above (which as you say, appears to be selling something).
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According to ISM, this would not be a likely scenario. I’d be curious if you can actually find someones personal data that shows someone utilizing 50% fat (or more) well above 4-5 mmol.
The graph doesn’t show 50% fat utilisation at VT2. Suggest you look at it again.
1g fat / min and 2g carb / min. Thats 9 cal from fat, 8 cal from carb. Thats 53% energy production from fat at LT2.
True in terms of contribution. This from one of coach Mark Pearce’s iron man athletes, a year apart. It can be trained and pretty well.
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Those two graphs do not show high percentage of fat oxidation rates above LT2. Even at the far end of the 2019 graph, 250w, which isn’t LT2, the athlete shows 75% energy production from CHO.
And yes that is my point, the first graph you posted shows equal or greater than 50% Fat Oxidation at or above LT2, which I do not believe is possible under normal conditions. I’m not saying it won’t change with training, Im just saying at above LT2, this result would be highly unlikely, if not undesirable.
Says who, what’s the guys LT2 and no it isn’t the previous graph?
Interesting comparison, but did the athlete get faster between these tests? I would like to see the power axis normalised for FTP. And the vertical axis is wrong: it needs a time-based unit: watts (joules per second), or kcal per second or minute, or hour, or whatever is defined as the test duration for that sample.
Half iron man time improved by 10 minutes
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The graph doesn’t show LT1 or LT2 or lacate levels. It’s just pretty easy to assume that if someone is still oxidizing a high amount of fat for fuel, that they are not above LT2.
You are jumping to a whole load of conclusions based on a bunch of assumptions. You seem to think burning 1g/min at LT2 isn’t possible, you’d be wrong.
Substantial!