@Dr_Alex_Harrison thanks for sharing advice on carb intake. Personally, I cannot wait to try these fuelling strategies as I can’t count the amount of years I’ve been grinding through workouts feeling absolutely empty and being totally flat when it comes to intensity, even when naturally that is my strong point.
After dabbling with low carb/paleo 10 years ago my default carb intake has been moved so low that despite trying to increase it over the last years, I fear it’s still way off.
Cheers
With regard to the BCAA study, is it possible that blunting the muscle damage and fatigue by-products might improve your performance in that individual workout/race, but decrease the training effect long term? Similar to how you would not want to load up on antioxidants after every workout.
From the 2015 Rowlands Review, (PDF linked previously, for clarity)
I think you’re right, there. I think most of them are wrong, respectfully, of course.
To be very clear on my specific claim: I think that the optimal ratio for performance enhancement, all things considered, is probably closer to 1:1 than 2:1. I think it’s sufficiently close to 1:1 for me to use principally sucrose in my intra-workout fueling.
If I had to put best-guess on the “best possible ratio,” while considering all factors (including sweetness and real-world consumption desire), I think take a stab at 1.2:1, glucose:fructose, and would use maltodextrin for the slight glucose overage. Real world: I’d just use sucrose and Gatorade because cheap/easy.
Related product anecdote: Maurten claims a ~1.25:1 ratio, if I recall correctly, and I suspect that’s the principal reason it works so well for so many folks. (not hydrogel)
Interesting screenshot from another related thread:
Possible? Maybe! Evidenced? No, I don’t think so. I think the mechanism for any increased performance intra-session by way of BCAA use stems from cognitive enhancement, not muscular.
Flow formulas is ~1.25:1 ratio as well.
I have reviewed the O’Brien supplementary info (and maybe screenshotted/shared it in another TR thread before, for context.)
For that reason, I have proposed various future research here and on slowtwitch, in case other researchers were reading, as well, because you’re right, no one has done a very comprehensive study looking at higher rates of consumption simultaneously with sugar ratio inquiry. And it is quite possible that rate of consumption varies the optimal ratio.
Do you mean risking GI issues? Just clarifying for my understanding.
Certainly my personal experience, along with many of my clients points to >>50g/hr fructose consumption being very tolerable if that’s of any informational value. I have several clients who consume 50-70g fructose, hourly,
without GI issues.
I suspect this will more than saturate glucose absorption and result in GI issues. Do you have any evidence that >80g/hr glucose per hour can be comfortably absorbed?
It is my present understanding that the very high rates of consumption work better when glucose doesn’t exceed much over ~75g/hr.
Do you happen to work for or consult any supplement companies? Asking only because of your PhD in ChemE and it sounds like you might be a good fit and hope that this does not come off as an inflammatory question.
Great point.
I think you’re well-read and well-practiced enough that I’ll ask the following: what gluc:fruc ratio would you recommend / personally do, for someone who is targeting the following consumption rates? Curious to hear your thoughts.
100g/hr
120g/hr
140g/hr
PS. much respect for the work you do. My mother worked in immunology for years.
That makes 2 of us. grabs half-consumed bottle in fridge from wife’s ride last week… tastes… “Yeah that’s probably got 200g carbs” adds water and throws it on bike
I don’t think you will see compelling evidence in the literature for a long time, especially if looking for bike performance improvement.
Reasons:
It’s going to take special researcher to carry out something like that.
While my opinion of approach is slightly different, I don’t blame you one bit for holding yours. I agree: GI issues will FAR outweigh the small performance gains, and are to be avoided at all costs.
Cool. Seems quite reasonable.
Interesting!
Love it.
Interesting. I initially started with the 90g 2:1 split but eventually transitioned to 110g/hr with a 60g/50g dextrose/fructose ratio.
From my understanding the glucose transporter SGLT1 saturates at ~60g/hr and additional fuel should be fructose. I also saw that GLUT5 maxes out oxidation rates at around .8g/min so ~48g/hr?
I am aware that this number could possibly vary between individuals depending on previous exposure to carbohydrate intake. It would be interesting to see a study where they have subjects fuel with high carb intake for long period of time and then retest oxidation rates.
I have been trying to find a sweet spot of receptor saturation while also finding a sustainable concentration/fueling rate for my palate/stomach. Thinking I may try experimenting with higher fueling rates after reviewing this, I only get stomach distress if the concentration is too strong, the actual carbohydrate amount does not seem to be an issue so I am thinking it may be a good idea.
I need to give this a go. From a calorie/hr perspective that is HUGE if you can increase from ~360kcal w/ the 90g carb mix up to 500-640kcal/hr.
Yup! Game-changer for >3-hr rides.
Does anybody have an effective way to package your homemade drink mixes for 4-6 hour races where you’ll be starting with two bottles mixed but relying on plain water hand ups mid race? I like the satchets that SIS beta fuel comes in. They fit in jersey pockets nicely and easy to open and dump into a bottle.
Anybody got any ideas?
@zpt122 , Ziplock bags, snack size.
Soft flasks in the jersey pockets
For 4-6-hr events I’d just do one ultra-concentrate bottle and one fresh water. 4-5-hr rides for sure.
400-500g carbs + 5-6 tsp sodium citrate + 400-600mg caffeine powder in a 1L bottle works fine for me, logistically.
Much longer than 6 is where it starts to get challenging. (>600g carbs in a 1L bottle isn’t fun!)
I can see the benefit of those high carbs drinks for longer but is there any real benefit for something like a 90min high intensity workout?
I hadn’t considered going that route. Holy crap! 500-600 carbs in a bottle. Does the powder dissolve? And how are you tracking how much per hour you drink?
What glucose:fructose ratio would you do for that much in one bottle?
I like this idea as it makes everything much simpler
Clear bottle with Sharpie Marker tick marks. Find a consistent recipe paired with 10% tick marks on the bottle makes it a little easier to track for me.
If you use the suggested bottle that “Doc” @Dr_Alex_Harrison recommends, pour in 3oz of water, sharpie, another 3oz, sharpie, etc. I know it’s a 33oz bottle but you have 2 options…leave 3oz of room at the top of the bottle (especially for shaking up before a drink) and each tick mark will be 10% of your 30oz recipe or fill it all the way up and the 3oz tick marks become roughly 9% of your 33oz recipe.
I used to be convinced not, but it’s cumulative stress on the glycogen stores that needs to be considered. If you’ve a heavy, consistent training load then, yes, I would consider them them necessary.
Slowly chipping away at stores may not negatively influence performance immediately, but it will eventually. Sure, you could gut out one 90 min high intensity session on no fuel, but it could catch up with you.
OTOH if you’ve a couple of days before the next heavy session and providing you’ve a decent diet, then perhaps not. Bit of experimentation needed.
Most of it, yes. Definitely all of it by the first top-up of water at the first water grab.
This is a great question. When I started, I did. Then I realized… the goal is fueling maximization, and the primary limiter of that is gut tolerance. So, when I really want to be serious about my fueling I’m pretty much just drinking the beverage(s) and water at whatever rate yields “barely uncomfortable” or “just shy of discomfort” the whole time.
Just slightly more glucose than 1:1 gluc:fruc. Probably 1.05:1 or 1.1:1 gluc:fruc.
Yes, without a doubt there is a benefit to carb consumption, but probably not >100g/hr for that short of a workout.
(table from my book, which out of respect to coauthors, specifically Dr. Mel Davis, the coauthor that I am NOT married to and sharing a bank account with lol, I probably should have been linking to every time I have shared the table… )I personally would probably target about 60g/hr for a 90min ride… so 90g, total.
