Hey,
based on our previous work from a similar study design, we thought that this much fluid should be sufficient. Keep in mind that the air conditioning in the lab works very well and that we also took care of very good air flow. As far as I remember, body mass loss was present, but was within expected limits (i.e., no real dehydration). If I was to ride outdoors or in the heat, this much fluid definitely wouldn’t have been sufficient.
And we haven’t added sodium, as I don’t really think it has a lot of effect on absorption. Also - we’d be increasing already relatively high osmolality of the drink, so not ideal scenario.
Higher oxidation rates? No clue! I have never even piloted higher rates. Javier Gonzalez tried something like this and oxidation stopped at a similar number. But keep in mind the intensity here was much lower tha in our case.
Did you enjoy the Friday night beer(s)? And if yes what were you drinking?
Thanks, really appreciate the reply and details. I have done plenty of 2 hour rides without fueling, when timed to coincide with a post ride dinner. And done some really strong 4-6 hour morning rides at 60g/hour Roctane bottles plus real food.
It’s that 2-4 hour middle ground of endurance riding on the weekends that I’m experimenting with - the duration requires more attention to fueling plus my usual issues with not wanting to wake up at 5am to eat, and body taking longer to get moving on Saturday morning.
That Elysian sounds good, I’m just so-so on Space Dust. My wife keeps telling me to try uncrustables on rides but they remind me of packing lunches for our girls back during the elementary school years.
Last week just before leaving for a hard 2 hour interval afternoon workout, I ate two bananas and slammed a 60g / 250 calorie 24 ounce bottle (Gu Roctane mix). That seemed to work well. This morning I did essentially the same for 90 minutes, except I started drinking the bottle on the bike.
Exactly! Last week I started in 94 degree heat and slammed pre-ride so I had 52 ounces (24 + 28 oz) on the bike without having to put a third 24 oz bottle in my jersey pocket.
Man there is a lot to digest here and I’m a bit in the weeds. I used to do 1/0.8 malto/fructose but out of simplicity I switched to table sugar at 90g an hour.
Am I missing potential benefits? Should i add malto or fruct to my table sugar?
I was under the impression that table sugar was relatively close(enough) to 1/1 malto/fruct.
And this is where I struggle. I race 3-4 hour events. I’ve worked on building up to 90g/hr on training rides and then ended up having a much lower IF (but higher RPE) in races.
In my last race there was almost an hour where I averaged 154w (peloton was taking a nap) am I still supposed to consume 90g/hr? That’s top of Z1 for me.
one interesting thing to take into consideration is that most people have a basal metabolic rate of about say 2000 calories per day (may be lower or higher). So there is a constant 100 calorie drain without intense exercise. The the general calculation for kJ to calories is about 1:1 or less so even noodling along at 150 watts avg per hour that is another 540 calories/h (source: kJ to Calories Conversion: How many calories do I burn cycling? roughly 3.6x average power)). 90 g of sugar is 360 calories per hour, so you will not replenish all of the loss so (one is likely burning at least 500 or 600 calories/h) I would suggest that it is good idea to keep as many calories coming in as possible regardless of effort. edit, 1:1 kJ/ calories not watts…
Hi @Dr_Alex_Harrison
In a similar vein, I am lost on this thread (as @freshturk highlights) and another larger one on ths forum.
Please point me in the correct direction.
I would like to be consuming 75g(carbs)/hour in a 600ml bidon.
What mass/weight of each maltodextrin, fructose and sodium citrate ingredient do I make for a 1:0.8 solution to use in that bidon?
Is there a minimum/maximum serving of sodium citric to use to be effective or mix to taste?
Would I make a large batch and mix it all together and then measure out x?g of the combined ingredients as a serving for that bidon? What is that serving size in grams?
I would appreciate others who know to comment as well, but I see that most people tag the Doctor in the house.
one question, do you plan to drink 600 ml / hour? if so then it is easy to calculate the carbs side, of the 75g, 42g would be maltodextrin and 33g fructose to give approx 1:0.8 ratio maltodextrin: fructose. If you plan to drink all 600ml/ hr then 75 g of this mixture. Dr Alex does recommend higher than 75g though and is pushing towards 120g carbs per hour if you can tolerate it. On a Slowtwitch thread Dr A suggests 2 tsp sodium citrate (~2000mg sodium) per 1 liter bottle so ratio that to 600 ml so a little more than 1 tsp sodium citrate.
I like to also have some sort of solids with my ‘drink’. I do try a 600ml bidon per hour amongst another bottle with NUUN electrolytes and having plain standard water. I will likely reduce the 600ml/hor carb drink to a lessor amount, only to be able to finish a drink within the prescribed hour to ensure I am getting sufficient fuelling.
Using SIS Isotonic gels which is 25g per gel and the SIS Chews which has 7g per chew with 45g in each ‘bar’.
This allows me to increase or decrease accordingly with my aim to be around 95-110g/hour.
Practically it puts me at a bidon with 3 chews, or a bidon and a gel, and/or a chew, and some other permutation thereof.
Been using Tailwind which has not been effective for me, have turned over to 32gi which has been better but has a practical issue that when making a concentrated mix, a fair amount settles at the bidon base and is not absorbed. The SIS Isotonic gels has been the most palatable gels cross them all, the texture does not lead me to want to throw up. Ideally if they had a higher carb content, I would be golden with nutrition.
He’s agreed to do an interview/podcast style video recording with me. If I have my way, it’ll be like 2-3 hours of talking nutrition shop. I think the main finding we’ll have from our recorded conversation is “who can talk about endurance fueling longer?”
I’ll be sure to touch on this “testing the extremes” subject.
This would be awesome. I’m grappling with just coming to terms with 90g/hr. My fear is by upping my drink mix to 70g/L (+ 1 gel) per hour the hypertonic solution won’t be hydrating enough. I’m already a crazy salty sweater and carrying more than 2 litres isn’t possible.
I have a race coming up with an estimated finish time of 3:35. I can take 2.7 litres with me which leaves me a bottle short. If I stash a bottle on the course I risk losing the group (and losing the race). If I carry on without it I risk dehydration and/or fading in the last hour.
I wrote you an app instead. Alacrity FUEL. Should release within a month. Hoping much sooner. Doing final pre-release bug-smashing now. Reviews from one of the beta testers today:
“It’s ace!” so my ego flew high for about 3 seconds until I found another edge case bug.
You have nothing to worry about.
Here’s why:
Hypertonicity can cause worsened hydration 3 primary ways:
Slowed absorption of fluid from gut to bloodstream.
Diarrhea.
Diuresis.
Only the latter two are actually causing water loss. The first is just causing slowed absorption. Slowed absorption won’t be your problem if carrying a fixed amount of fluid. It’s going to get absorbed.
Usually, during exercise, number 2 (no pun intended) happens at lower intake hypertonicities than number 3.
So, unless your fuel is SO hypertonic that you’re getting diarrhea & intestinal cramping then you’re no where near achieving diuresis. (you won’t at 90g/L or usually even 120g/L. Shoot… that study I just reviewed used 200g/L (that’s 20%), and found very low/few GI issues.)
Hypertonic solution isn’t dehydrating via diuresis unless it’s ridonkulously hypertonic. Ridonkulous = science term for like 5x normal recommended sodium amounts. As far as I know, you can’t get diuresis from concentrating carbs in a beverage. If anything, the opposite. You’ll get diarrhea way earlier if you overdo it during exercise.
FYI: Diruesis water loss from water going from blood (hydration) → kidneys → urine in ureter → bladder → out of body.
That’s what many folks are thinking of when they talk water loss via hypertonicity (sea water effect.)
Just drink all the fluid by 15-30 minutes before race-end and you’ll have absorbed it all, with no issue, even if there is marginally slower absorption due to 90g/hr intakes.
Awesome! Thanks for the in-depth reply. And to confirm. I should finish the 2.7L by the 3 hour mark and push the last 30 min sans fluid? I could in theory still take another gel at 3 hours as well?
