You still burn the same carbs from muscle stores. No matter 120g/hour or 90g/hour. So no muscle glycogen sparing from going 90 to 120.
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So no point ingesting more than 90g/hr? At least based on this study?
But will burn more carbs from what you are drinking.
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From my quick skim of the start of the paper, I donāt think they were evaluating/comparing performance - ie they were focused on measuring exogenous/endogenous carb usage. (see quote below.)
Itās possible that 120g/hour enables higher performance than 90, but that would take other experiments to confirm. I think some of the older studies at higher than 90 were using the 1:2 ratio, not the 08.:1 used here.
Since it looks like the 3 hour exercise sessions were at a fixed output, the energy used should be the same, so I guess it looks like they used less fat in the 120g/hour case?? Maybe thatās discussed later int he paper. There clearly seems to be more work to be done to have a good understanding of the limits of carb usage, and what rates are optimal for different situations.
Thus, the aim of the present study was to compare exogenous and endogenous CHO oxidation rates after ingesting CHO at the widely recommended rate of 90 g hā1 in 1:2 (Burke et al. 2011) with the rate of 120 g hā1 in 0.8:1 (fructose to glucose-based CHO ratio) as has been more recently advanced (Hearris et al. 2022 and Rowlands et al. 2015).
Mate! Sober up! We need to know. 
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Iām still wading thru it, of note:
The exercise consisted of 180 min of cycling at 95% GET (mean 256 Ā± 16 W, range 235ā295 W).
From my point of view thatās a high power output for 3 hours. Itās what I can do for about an hour at threshold. My best 3-6 hour power is 175-195W. That was fueled around 70-90 grams/hour. Iāll run some calcs later, maybe I could push harder with more fueling, or maybe Iām ftp limited.
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IRBs are only a problem at actual research institutions, right? If a private lab wants to do research without it, and can find people who will agree to āHey, Iāve got this new nutrition regimen which might make you 1% faster or might leave you writhing on the floor in painā (hmm, where could you get gullible people like that, I wonder?), you can do it without an IRB. Though thereās that issue of fundingā¦
I would suspect that based upon that it is DE 10. There is always a range for both the sugars and the DE so that makes sense to me. When I was writing I was tempted by the range I was seeing to say 2-4 g sugars so it is not out of the ordinary.Usually the two sugars present are fructose and maltose. This stuff would be minimally sweet and have very low free sugars.
so in essence you get more carbs burned thus more energy at the lower ratio than the higher ratio, though they still saw utilization of endogenous carbs in both cases and since they suggest no sparing in either case it means the lower ratio is still the better from an energy input point of view.
Youāre right. Bodpods are notoriously unreliable. Throw that data away and forget it ever happened.
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Talking with lead developer tonight about when Iāll be sending out the email to you all. Within the next few days for sure.
The difference, in my experience, is that the folks within the IRBās devalue sport performance as āworth researchingā and so theyāre much less willing to accept possible āharmā to subjects to answer such an āunimportantā question.
Very soon!
Iām so glad you did. I hadnāt seen it. Iāve added this to a list of things to film this weekend. This and 3 other studies from 2022 are making for an exciting year, (itās about time!) in endurance sport nutrition science.
Hereās the summary of each of those three upcoming YT videos:
- Marathoners spare muscle damage w/ 120 vs 90.
- Gels & Chews + water work as well as carb solution + water.
- Solid foods do not, but people (and researchers) want them to.
Soon via youtube.
Liver stores may matter.
Things may change as duration exceeds 3 hrs.
Performance is enhanced and muscle damage is reduced, with higher fueling, when possible.
Table in this video. carbs
Correct.
Yes but to get it peer reviewed and in a journal, youāll still need IRB approval.
Our app will fund itself, I hope. Iāll collaborate with research institutions and users once weāre āthere.ā
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PS. Shout out to @timpodlogar for the awesome work.
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Hot off the presses, it was published that same day. Saw Tim Podligar tweet.
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The tweet from the man, the myth, the legend himself. https://twitter.com/timpodlogar/status/1557681283370713091/photo/1
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@Nate_Pearson & team, good on you.
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Did I misread the fluid amounts? I recall something like 600mL per hour but may have sped past that.
Going and rechecking now.
I also inquired of @timpodlogar on twitter if theyād included any sodium. Seems important but perhaps Iām overestimating the importance of such an inclusion for carb absorption. Iāll need to recheck this in the literature to be absolutely certain that sodium enhances carb absorption at the very least through better hydration maintenance during heavy sweating, as is common in a lab.
Sorry its Friday and Iām feeling a little lazy, will you or @Dr_Alex_Harrison help me a bit on the math and my logic chain? Lets use this recent Two Hour Tuesday with some guesses on carbs from Xert/INSCYD:
- 2:03:06 duration
- 184W avg power, 188W normalized
- Xert: about 200g carbs
- INSCYD: about 170g carbs
Because Iād like to use that as a baseline for thinking thru longer 3 and 4 hour endurance workouts. And yeah, endurance workouts use less carbs than races and longer sweet spot / threshold workout sessions.
Ok so Xert and INSCYD ballparks are in the same field, lets use 200g to make it simple.
Which then leads me to consider what was on-board before starting. What about muscle/liver glycogen stores, assuming they are topped off pre-ride? Iām 90+kg with relatively good 8+ hour/week aerobic fitness for my age, and eat a high carb diet. Something like this:
- roughly 700g muscles
- roughly 100g in the liver
right?
But for muscles thatās whole body stores.
Cycling uses less active muscles, and I donāt know how to estimate the amount of muscle in my legs. So Iām gonna ballpark it at 400g based on some random reading of INSCYD.
So if my leg muscles have 400g, and I burn 200g from muscle stores during the 2 hours, thatās half still in my muscles. Thatās the no fueling during ride scenario (ignoring glycogen from liver), right?
Going to back to the study now, I donāt know my gas exchange threshold or respiratory compensation point. So I want to roughly translate that to % IF so I can possibly use it. In the study, 3 hour power was at 95% GET. Lets be sloppy and use 328W average RCP as roughly FTP (its not), and exercise was performed at average of 256W. So thatās roughly a 78% IF, really really rough the exercise was 3 hours at low tempo. Right?
Well 256W for an hour would be a good day for me, a really good day would be 270W for an hour. Three hours? Thatās more like 175-200W and 65-75% IF. This year Iāve had some strong 2 and 3 hour endurance training efforts around 75%. So roughly similar intensity as the study, not the same absolute energetic requirements but assuming some linearity I might be able to use some ratios for a rough broadside approximation for myself.
So again, going out on a limb, lets assume at 75% my ratios of exo/endo carb oxidation would be vaguely similar to those in the study:
Again those cyclists have higher vo2max and absolute power, burning a bit more absolute, but since they were lower tempo and I was at zone2/tempo border humor me that the ratios might be considered a ceiling for my effort.
So from the study graph I posted above, lets ballpark my endogenous carb oxidation rate at 2g/min, or 120g/hour. So for 2 hours that would be 240g. Clearly that starts to empty the tank - the 400g stored in muscles at start. And it gets dicey at 3 hours for sure.
Going with these admittedly pseudo random ballpark numbers, whatās to gain increasing from 60g/hour Roctane (not sure of ratio) to 120g/hour carbs at 4:5 fructose-to-glucose (0.8:1) ratio?
Also, one thing I did not see considered in the article is recovery (replenishing stores). Just being captain obvious, and seems like a much harder thing to quantify.
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no worries - Iām heading out on the bike for 2 hours and about to chug a couple of carb bottles, just not the TGIF carbs your guzzling lol
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Okay thatās what I thought. Here was my question to @timpodlogar about that:
I look forward to his response. Heās probably asleep right now, given that heās in Europe somewhere.
I know for sure Iād have mild GI distress at that consumption rate, probably by about 1h-40min into the session, with that little fluid intake. If allowed fluid + sodium, Iād suspect it could be totally attenuated.
FWIW: My age, height, weight, and power numbers are within range of the subjects of that, though on the upper end of weight range, and middling for power. 