>120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise.

Oct 24, 20 14:18

Post #1 of 41 Views: 2885

Would love to hear stories that hit me right in the confirmation bias about how folks have consumed and benefited from far greater than the oft-cited recommendation of 60-90 g/hr of carbs during endurance activities lasting more than 2 hrs.

I'll start.

1. My first century, ~116g/hr riding a 2006 Trek 1200 with a mix of Tiagra and 105 components. 6'1", 215, ~10% fat. (former strength/power athlete). Completion time: blazing 6 hrs & 30 minutes. Estimated average power: 150-170 W. Total carbs consumed: 750g. Total calories: ??? I stopped for cookies... it was a gran fondo. More than 3300kcal for sure, in total. Was ravenous and hypoglycemic afterwards. Ambient conditions: ~60-70 degrees, sun, calm, comfortably low humidity. (Summer in PNW).

2. More recently, random 2-hr experiment on gut tolerance (just over 2hrs): Consumed ~300g carbs. (~1200kcal). ~150g/hr. 250g carbs from sucrose. 50g from Gatorade. Added 1 tsp sodium citrate. Ambient conditions: ~70-75 degrees, sun, moderate humidity. (Early fall in Carolinas). 6'1", 208, 10% fat (now-lighter, former strength/power athlete). Felt well-fueled and only reasonably hungry afterwards. Estimated average power: 200 W.

I don't intend for this to be a discussion on the utility of such approaches, though happy to entertain any discussion.

Just want to see what folks do for higher carbs.

Alright, brag it up. Let's hear your "I ate/drank THIS much" stories. "This athlete did X" also accepted.

Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
-------------------------------------------------------------------------------------------------------------------------------------------------
📱 Check out our app → Saturday: Pro Fuel & Hydration, a performance nutrition coach in your pocket.
Join us on YouTube → Saturday Morning | Ride & Run Faster and our growing Saturday User Hub

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [DrAlexHarrison] [ In reply to ]

Oct 24, 20 14:32

Post #2 of 41 Views: 2866

In a podcast with the MX Endurance guys, I believe Adam Hansen talked about shooting for 120g/hr and doing everything with gels. And he talked about taking a gel halfway thru an IM SWIM to keep the calories going. He was pretty clear that he thought keeping his fueling at this level would definitely be helpful over what he thinks most triathletes are doing, and he said he can do it all day every day basically when cycling.

Interesting ideas for sure. I always thought the idea of 400 calories an hour being the max was counter intuitive, as people are different sizes and shapes. A blanket amount doesn't make much sense.

Looking forward to seeing where this thread goes.

ETA the bold word swim as it's critical haha

DFRU - Detta Family Racing Unit...the kids like it and we all get out and after it...gotta keep the fam involved!

Last edited by: dfru: Dec 30, 20 8:00

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [DrAlexHarrison] [ In reply to ]

Oct 24, 20 17:28

Post #3 of 41 Views: 2813

Sugar is pure energy. The more you can tolerate and digest, the longer you’ll be able to produce high power. Drown yourself in sugar if you never want to bonk

The real trick is dealing with the sugar high effects...

Last edited by: rsjrv99: Oct 24, 20 17:31

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [DrAlexHarrison] [ In reply to ]

Oct 24, 20 18:06

Post #4 of 41 Views: 2778

The interesting thing for me would not be how many / hr, but how many hours.

I can consume some pretty high cals on the bike, and keep taking those for the 5hrs (6 hours in training). But where' I'm coming unstuck is after the bike where I am dropping the intake, but struggling with the post effects.

So for a 70.3 with the same cal intake on the bike and then the run, I'm A OK. On the bike in IM then I'm fine for the 5 hours. So it's neither the cals on the bike or the cals on the run that are 'flawed', it's the combination of cals on the bike for 5 hours followed by attempting the cals on the run after 2 hours. Obviously hard to test this in training.

(and in answer to your question at 6'4" and 85kg then I've been doing 90g/kg/hr on bike and 60 on the run.

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [Duncan74] [ In reply to ]

Oct 24, 20 18:29

Post #5 of 41 Views: 2759

Duncan74 wrote:

The interesting thing for me would not be how many / hr, but how many hours.

I can consume some pretty high cals on the bike, and keep taking those for the 5hrs (6 hours in training). But where' I'm coming unstuck is after the bike where I am dropping the intake, but struggling with the post effects.

So for a 70.3 with the same cal intake on the bike and then the run, I'm A OK. On the bike in IM then I'm fine for the 5 hours. So it's neither the cals on the bike or the cals on the run that are 'flawed', it's the combination of cals on the bike for 5 hours followed by attempting the cals on the run after 2 hours. Obviously hard to test this in training.

(and in answer to your question at 6'4" and 85kg then I've been doing 90g/kg/hr on bike and 60 on the run.

Would be interested to hear what your hourly fluid and sodium intake is. Entering the run dehydrated could explain the gut disturbance.

What's the glucose fructose ratio in your carb sources?

Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
-------------------------------------------------------------------------------------------------------------------------------------------------
📱 Check out our app → Saturday: Pro Fuel & Hydration, a performance nutrition coach in your pocket.
Join us on YouTube → Saturday Morning | Ride & Run Faster and our growing Saturday User Hub

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [DrAlexHarrison] [ In reply to ]

Oct 24, 20 18:36

Post #6 of 41 Views: 2754

Don't believe it's dehydration on the bike - I always go pee in T2. I pretty much nail 700ml of nuun an hour on bike.

Where I struggle is then keeping that hydration going in on the run after the 5hrs on the bike. Noting that in training and for 70.3 I'm fine to get the hydration in, just struggle after 5hrs. I will reply later with the details of the intake - I'm a geek so use timers and a strict food plan so just need to grab my wrappers later to get the exact numbers across gels, chomps and bars. (will cheat and fakescan the barcodes into myfitness plan).

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [Duncan74] [ In reply to ]

Oct 24, 20 18:45

Post #7 of 41 Views: 2746

Duncan74 wrote:

Don't believe it's dehydration on the bike - I always go pee in T2. I pretty much nail 700ml of nuun an hour on bike.

Where I struggle is then keeping that hydration going in on the run after the 5hrs on the bike. Noting that in training and for 70.3 I'm fine to get the hydration in, just struggle after 5hrs. I will reply later with the details of the intake - I'm a geek so use timers and a strict food plan so just need to grab my wrappers later to get the exact numbers across gels, chomps and bars. (will cheat and fakescan the barcodes into myfitness plan).

Might be worth trialing 900-1100mL and adding sodium citrate on top of the nuun if your sodium intake is under 1000mg per hour. Has made a difference for a few of my clients but admittedly I've never run after >5hr biking. Longest activities have been 7-10 hrs riding. My longest bricks have been 4hrs tops.

Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
-------------------------------------------------------------------------------------------------------------------------------------------------
📱 Check out our app → Saturday: Pro Fuel & Hydration, a performance nutrition coach in your pocket.
Join us on YouTube → Saturday Morning | Ride & Run Faster and our growing Saturday User Hub

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [DrAlexHarrison] [ In reply to ]

Oct 25, 20 2:44

Post #8 of 41 Views: 2672

Interesting discussion. To me it looks like there is maybe a fairly narrow range here.

I'm guessing Duncan74 means 90g per hour. For him that's about 1g per kg per hour on the bike.

DrAlexHarrison, bigger guy, 100+g per hour, also about 1g per kg per hour over a long ride. Not sure how valid rates for short rides are- for example, someone could ride for 5 minutes, drink a glass of orange juice, and claim 1000g per hour.

Me, smaller, 60g per hour on the bike is about what I can handle , also about 1g per kg per hour. On the run I often struggle to take anything though.

Last edited by: fruit thief: Oct 25, 20 2:55

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [DrAlexHarrison] [ In reply to ]

Oct 25, 20 5:13

Post #9 of 41 Views: 2612

I'm sure it's been posted here many times, but FYI:

Last edited by: HardlyTrying: Oct 25, 20 5:15

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [DrAlexHarrison] [ In reply to ]

Oct 25, 20 5:43

Post #10 of 41 Views: 2591

though I have never been too concerned with intake per hour, I have done something to make a very high carb per ml solution. The big thing is osmality. Osmality is related the number of molecules not weight, so for that reason the osmality of maltodextrin (a large molecule is lower than fructose, glucose and sucrose on an equivalent weight basi..We can get into the intro chemistry class on moles etc but you can load a whole lot more calories per ml by using maltodextrin. The energy release kinetiics are nearly identical to sugar but a bit slower. So that is why most energy drinks based upon maltodextrin also have a mix of glucose and fructose added. The three items are cheap and easy to acquire. So I have played with loading maltodextrin plus a small amount of fructose and glucose (plus a bit of sea salt to get a multi mineral blend) to my energy drink to find the tipping point for my stomach. I use a ratio of glucose to fructose of 2:1 and about 30g glucose per bottle of so. Once you find what your stomach will accept I just flavour with lemon and lime juice and off we go.

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [DrAlexHarrison] [ In reply to ]

Oct 25, 20 12:56

Post #11 of 41 Views: 2504

I have a very intolerant stomach and realized I gravitated towards shorter races over the years because I hate the upset stomach/bonk at the two extremes. My only two attempts at multisport races longer than five hours both ended up as dnf's. My best half-IM ever, I guess my muscles were just topped off because I went about 4.5 hours on 40 ounces of water and maybe 200-300 calories.
A couple of years ago I tried my first gravel event--72 miles with 7,000 feet of climbing--and ended up on the side of the trail both bonking and with still with a stomach that seized up after partaking of mid-race hor d'oerves. A very nice rider stayed with me until I could ride back to the start, but I threw up and then could not stomach any food for hours. Since then I have determined I can take in about 100 calories before the start of a long gravel ride and then about 50-100 calories an hour for two to three hours. After that, if I try to consume more my stomach just shuts down. I either finish and perform well or bonk and dnf. My only race this year (Cedar City Fire Road 100K) was a dnf.
My marathoning was the same. First race, undertrained and clueless was still my best because for whatever reason, my muscles were just full that day. I ran pretty fast on just a bit of water. Subsequent attempts with double the mileage and lots more experience never came close to that first effort and several ended on the side of the road bonked, or walking with severe stomach cramps.
If people can really consume that much it must make long events a lot more palatable (pun intended) :)

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [rsjrv99] [ In reply to ]

Oct 25, 20 14:45

Post #12 of 41 Views: 2425

rsjrv99 wrote:

The real trick is dealing with the sugar high effects...

The real trick is dealing with the impaired digestive capability of the digestive tract during high intensity exercise. Eat too much and you end up with bad digestive issues. Bloat, gas, etc.

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [trail] [ In reply to ]

Oct 26, 20 0:52

Post #13 of 41 Views: 2285

A general rule is guidance, however, its a pretty complicated balance

If you race at a high intensity you impair the digestive system's ability to absorb carbs. On a long distance ultra event, I tend to take more real food and more than 90g/hr. If I race an HIM where I am close to threshold most of the time I only take gels and liquids and limit to 100g/hr

On a long distance race, you cannot rely purely on Carbs.... even if you drown yourself in suger, you will still run low as you are using more energy than your body can absorb. If I am racing an Ultra event, I am using around 700Cals per hour, I may be able to absorb 400Cals (at a push), so still have a deficit of 300Cals per hour, which comes from burining fat. During a short event like a HIM I am burining up to 1000Cals per hour, but can absorb 300Cals (due to higher intensity) so I am at a deficit of 700Cals per hour. Therefore I need some level of fat adaptation.

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [fruit thief] [ In reply to ]

Oct 26, 20 18:29

Post #14 of 41 Views: 2132

It's actually a benefit to be 60kg! Carb g/hr tolerance is not related to body mass.
There are a couple of later steps where higher muscle mass might have an influence, but the biggest bottlenecks are much earlier in the GI tract and so size-independent (and trainable).

But to address the OP, I have not had a client able to manage over 100g, and getting up to 90 for a full IM is challenge enough typically. But to be fair, I have also not had a client (including myself) able/willing to commit to the nutritional training a nice high CHO rate requires.

http://www.extramilenutrition.com

Last edited by: greenjp: Oct 26, 20 18:30

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [DrAlexHarrison] [ In reply to ]

Oct 27, 20 2:38

Post #15 of 41 Views: 2070

In an LD-Ironman:
4 powerbar-gels/h.
1 powerbar-gel has 28g carb, lets say 25 because you can't empty the package totally clean => 100 g/h.

During the bike as well as during the run. That's about 36 gels (actually 32 because the first hour on the bike I'm on bars instead of gels).
That's about 0.9 kg carbs on that day. Which is again about 4000 kcal.

Edit: actually it's more, I forgot the intake of carbs by electrolytes like Gatorade. I never calculated this, because I drink electrolyte according to thirst. When it is hot more, when it is cold less.
So I take more than 100 g/h of carbs.

I weigh 85 kg.

Last edited by: longtrousers: Oct 27, 20 3:05

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [mattsurf] [ In reply to ]

Oct 27, 20 3:33

Post #16 of 41 Views: 2048

mattsurf wrote:

Therefore I need some level of fat adaptation.

Everybody has some fat adaption. There was a study* that made a minor splash about 5 years ago where they tested some highly trained athletes, maybe elites, who trained and raced very high carb and found that they burned a surprising amount of fat while running. My memory of that study is quite fuzzy, but I think it's true that you can train to burn more fat, but you still burn some % fat even if not intentionally fat adapted.

*not the FASTER study, which was about the same time.

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [HardlyTrying] [ In reply to ]

Oct 27, 20 3:55

Post #17 of 41 Views: 2035

HardlyTrying wrote:

mattsurf wrote:

Therefore I need some level of fat adaptation.

Everybody has some fat adaption. There was a study* that made a minor splash about 5 years ago where they tested some highly trained athletes, maybe elites, who trained and raced very high carb and found that they burned a surprising amount of fat while running. My memory of that study is quite fuzzy, but I think it's true that you can train to burn more fat, but you still burn some % fat even if not intentionally fat adapted.

*not the FASTER study, which was about the same time.

You are completey correct, everyone burns a combination of Carbs and Fat. I can't remember the exat stats, but even when fueled well on carbs, the body is still getting something like 30% of its energy from Fat while exercising. You can train the body to use a higher percentage of fat, which is the objective of some low carb diets, however, I am not a fan of these at all. Another way is to do lots of long distance training and training fasted so that your body gets accustomed to exercise where supply of carbs is low. This works for me.

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [mattsurf] [ In reply to ]

Oct 27, 20 4:21

Post #18 of 41 Views: 2029

mattsurf wrote:

HardlyTrying wrote:

mattsurf wrote:

Therefore I need some level of fat adaptation.

Everybody has some fat adaption. There was a study* that made a minor splash about 5 years ago where they tested some highly trained athletes, maybe elites, who trained and raced very high carb and found that they burned a surprising amount of fat while running. My memory of that study is quite fuzzy, but I think it's true that you can train to burn more fat, but you still burn some % fat even if not intentionally fat adapted.

*not the FASTER study, which was about the same time.

You are completey correct, everyone burns a combination of Carbs and Fat. I can't remember the exat stats, but even when fueled well on carbs, the body is still getting something like 30% of its energy from Fat while exercising.

If I look at the statistics of tests which I have done, the 30% you mention can only be an average. In fact, as I understand it, at intensities higher than a certain treshold the fat-burning is 0 %.

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [DrAlexHarrison] [ In reply to ]

Oct 27, 20 4:33

Post #19 of 41 Views: 2018

I’ve consumed 500kcal/hr before, so 1.6g/kg/hr of carbohydrate. Takes training and also good pacing.

Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [Duncan74] [ In reply to ]

Oct 27, 20 4:35

Post #20 of 41 Views: 2016

Duncan74 wrote:

Don't believe it's dehydration on the bike - I always go pee in T2. I pretty much nail 700ml of nuun an hour on bike.

Where I struggle is then keeping that hydration going in on the run after the 5hrs on the bike. Noting that in training and for 70.3 I'm fine to get the hydration in, just struggle after 5hrs. I will reply later with the details of the intake - I'm a geek so use timers and a strict food plan so just need to grab my wrappers later to get the exact numbers across gels, chomps and bars. (will cheat and fakescan the barcodes into myfitness plan).

You’re dehydrated

Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [trail] [ In reply to ]

Oct 27, 20 4:37

Post #21 of 41 Views: 2012

trail wrote:

rsjrv99 wrote:

The real trick is dealing with the sugar high effects...

The real trick is dealing with the impaired digestive capability of the digestive tract during high intensity exercise. Eat too much and you end up with bad digestive issues. Bloat, gas, etc.

An army marches on its stomach... lose your stomach in an IM and you’re done...

Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [HardlyTrying] [ In reply to ]

Oct 27, 20 4:39

Post #22 of 41 Views: 2007

HardlyTrying wrote:

mattsurf wrote:

Therefore I need some level of fat adaptation.

Everybody has some fat adaption. There was a study* that made a minor splash about 5 years ago where they tested some highly trained athletes, maybe elites, who trained and raced very high carb and found that they burned a surprising amount of fat while running. My memory of that study is quite fuzzy, but I think it's true that you can train to burn more fat, but you still burn some % fat even if not intentionally fat adapted.

*not the FASTER study, which was about the same time.

They’re elite because they burn fat, they don’t burn fat because they’re elite. It’s why they’re elite.

Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [longtrousers] [ In reply to ]

Oct 27, 20 4:40

Post #23 of 41 Views: 2005

longtrousers wrote:

mattsurf wrote:

HardlyTrying wrote:

mattsurf wrote:

Therefore I need some level of fat adaptation.

Everybody has some fat adaption. There was a study* that made a minor splash about 5 years ago where they tested some highly trained athletes, maybe elites, who trained and raced very high carb and found that they burned a surprising amount of fat while running. My memory of that study is quite fuzzy, but I think it's true that you can train to burn more fat, but you still burn some % fat even if not intentionally fat adapted.

*not the FASTER study, which was about the same time.

You are completey correct, everyone burns a combination of Carbs and Fat. I can't remember the exat stats, but even when fueled well on carbs, the body is still getting something like 30% of its energy from Fat while exercising.

If I look at the statistics of tests which I have done, the 30% you mention can only be an average. In fact, as I understand it, at intensities higher than a certain treshold the fat-burning is 0 %.

You’re never not burning fat

Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [ericMPro] [ In reply to ]

Oct 27, 20 5:13

Post #24 of 41 Views: 1998

For an AG athlete, I think I am pretty good at nutrition, I certainly know what works for me. However, after 2.5-3 hours I always hit a slight low, I need to back off just a fraction, after 30 minutes or so I am back to 100% and will then stay that way for many hours. I guess that this is the point where my body starts to use fat more effectively. I have done enough events to know that this is completely normal for me, and that there is no need to panic of change anything.

So a question for Eric, would this be typical for elite athletes, or are they sufficiently trained and adapted that there is no noticeable transition?

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [mattsurf] [ In reply to ]

Oct 27, 20 8:16

Post #25 of 41 Views: 1963

mattsurf wrote:

For an AG athlete, I think I am pretty good at nutrition, I certainly know what works for me. However, after 2.5-3 hours I always hit a slight low, I need to back off just a fraction, after 30 minutes or so I am back to 100% and will then stay that way for many hours. I guess that this is the point where my body starts to use fat more effectively. I have done enough events to know that this is completely normal for me, and that there is no need to panic of change anything.

So a question for Eric, would this be typical for elite athletes, or are they sufficiently trained and adapted that there is no noticeable transition?

Elite athletes are elite, extreme outliers. They're not just better versions of you.

That said, we're all the same kind of different... even elite athletes experience seemingly similar ups and downs.

Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [fruit thief] [ In reply to ]

Oct 27, 20 8:58

Post #26 of 41 Views: 1701

fruit thief wrote:

Interesting discussion. To me it looks like there is maybe a fairly narrow range here.

I'm guessing Duncan74 means 90g per hour. For him that's about 1g per kg per hour on the bike.

DrAlexHarrison, bigger guy, 100+g per hour, also about 1g per kg per hour over a long ride. Not sure how valid rates for short rides are- for example, someone could ride for 5 minutes, drink a glass of orange juice, and claim 1000g per hour.

Me, smaller, 60g per hour on the bike is about what I can handle , also about 1g per kg per hour. On the run I often struggle to take anything though.

Gut tolerances are surprisingly unrelated to body mass. My wife routinely intakes 120g carbs per hour for 2-4-hour efforts on the bike if sufficiently hydrated. She's 5'9", 63kg. I have a couple clients in the 55kg range that regularly do >100g/hr.

Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
-------------------------------------------------------------------------------------------------------------------------------------------------
📱 Check out our app → Saturday: Pro Fuel & Hydration, a performance nutrition coach in your pocket.
Join us on YouTube → Saturday Morning | Ride & Run Faster and our growing Saturday User Hub

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [ericMPro] [ In reply to ]

Oct 27, 20 9:00

Post #27 of 41 Views: 1699

ericMPro wrote:

I’ve consumed 500kcal/hr before, so 1.6g/kg/hr of carbohydrate. Takes training and also good pacing.

Good pacing is a great point.

Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
-------------------------------------------------------------------------------------------------------------------------------------------------
📱 Check out our app → Saturday: Pro Fuel & Hydration, a performance nutrition coach in your pocket.
Join us on YouTube → Saturday Morning | Ride & Run Faster and our growing Saturday User Hub

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [ericMPro] [ In reply to ]

Oct 27, 20 11:31

Post #28 of 41 Views: 1679

ericMPro wrote:

You’re dehydrated

OK, I'm always keen to learn, but in order to do that, I'll probably need a bit more around how/why you think that and how we can confirm your hypothesis. I have been dehydrated in races, and on rides and with clear symptoms of that. So I'd be a bit surprised if this was dehydration as to me then these things came up when I'd drunk a lot more, was in cooler conditions and also without the same symptoms. Also, and I appreciate this isn't the clearest indication, weight at the end of the race wasn't substantially lower than pre-race, and was heavier than in many training ride / runs, albeit noting that my training runs tend to max out at 33km (2 1/2 hr).

If it is dehydration can you be specific where - on the bike or in the run. Ie is the issue I'm starting the run dehydrated, or is it that the bike is fine, but I'm dehydrating over that first couple of hours on the run which is why I'm not having issues in 70.3 as whilst I am runnign a fluid deficit I'm not running long enough for it to become an issue.

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [Duncan74] [ In reply to ]

Oct 27, 20 12:10

Post #29 of 41 Views: 1668

Duncan74 wrote:

ericMPro wrote:

You’re dehydrated

OK, I'm always keen to learn, but in order to do that, I'll probably need a bit more around how/why you think that and how we can confirm your hypothesis. I have been dehydrated in races, and on rides and with clear symptoms of that. So I'd be a bit surprised if this was dehydration as to me then these things came up when I'd drunk a lot more, was in cooler conditions and also without the same symptoms. Also, and I appreciate this isn't the clearest indication, weight at the end of the race wasn't substantially lower than pre-race, and was heavier than in many training ride / runs, albeit noting that my training runs tend to max out at 33km (2 1/2 hr).

If it is dehydration can you be specific where - on the bike or in the run. Ie is the issue I'm starting the run dehydrated, or is it that the bike is fine, but I'm dehydrating over that first couple of hours on the run which is why I'm not having issues in 70.3 as whilst I am running a fluid deficit I'm not running long enough for it to become an issue.

you need to reconsider what your definition of "hydrated" is...

Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [Duncan74] [ In reply to ]

Oct 27, 20 14:48

Post #30 of 41 Views: 1633

have you done a sweat test, or even weighed yourself after those big IM training rides? you said weight wasn't a problem but are you talking about your weight on race day, or weight loss?

Also, when you are taking your ambient weather data into account, are you looking at relative humidity or dew point?

the world's still turning? >>>>>>> the world's still turning

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [Callin'] [ In reply to ]

Oct 27, 20 15:21

Post #31 of 41 Views: 1625

Callin' wrote:

have you done a sweat test, or even weighed yourself after those big IM training rides? you said weight wasn't a problem but are you talking about your weight on race day, or weight loss?

Also, when you are taking your ambient weather data into account, are you looking at relative humidity or dew point?

Sweat test - no
Weighed pre / post workouts and races. Yes, pre/ post every session, AM and PM every day for the purpose of being aware of hydration state.
And weight to inform weight loss. IMNZ they weigh you at registration and on the finish line. Before you are allowed into the finishers tent they weigh you on the exact same scale you used at registration to calculate weight loss and they direct you to either recovery tent or medical.
In training if I finish at home I weigh before and fluid in/out, if I'm finishing away then I take into account the volume/weight of fluid in my understanding of fluid loss.
Mostly temp, and RH, but for me in the locations I train/race then wind speed and sun intensity are big factors.

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [Duncan74] [ In reply to ]

Oct 27, 20 16:36

Post #32 of 41 Views: 1613

Duncan74 wrote:

ericMPro wrote:

You’re dehydrated

OK, I'm always keen to learn, but in order to do that, I'll probably need a bit more around how/why you think that and how we can confirm your hypothesis. I have been dehydrated in races, and on rides and with clear symptoms of that. So I'd be a bit surprised if this was dehydration as to me then these things came up when I'd drunk a lot more, was in cooler conditions and also without the same symptoms. Also, and I appreciate this isn't the clearest indication, weight at the end of the race wasn't substantially lower than pre-race, and was heavier than in many training ride / runs, albeit noting that my training runs tend to max out at 33km (2 1/2 hr).

If it is dehydration can you be specific where - on the bike or in the run. Ie is the issue I'm starting the run dehydrated, or is it that the bike is fine, but I'm dehydrating over that first couple of hours on the run which is why I'm not having issues in 70.3 as whilst I am runnign a fluid deficit I'm not running long enough for it to become an issue.

Gut sensitivity tends to be higher during running.

Gut sensitivity tends to be higher during higher intensity activity.

Gut sensitivity tends to be higher when dehydrated, even mildly. (~1% body weight loss, and dramatically beyond ≥2% body weight lost).

If sodium isn't matching fluid consumption at close to 1000mg/L (some folks benefit from 1200-1800mg/L), it could be leading to clinically irrelevant, but performance-relevant hyponatremia, meaning your blood volume is dropping JUST like if you were dehydrated. In hyponatremia blood volume drops as water moves into cells and out of blood, to ensure blood sodium concentration (among other concentrations) is maintained for life. One symptom of your body not getting enough sodium with the fluid intake is peeing. Drink a bunch of water absent sodium and you'll pee when you'd rather hold the fluid for performance reasons (cardiac output).

I looked up the Nuun sodium amounts. Looks like 600mg per liter. Looks like you're getting 420mg sodium from Nuun per 700mL of fluid intake. I'd say double your sodium intake. Maybe triple it.

Sodium Citrate is my go-to. No affiliation. Just cheap.

Switching gears, it could entirely be due to the sugar composition of your beverages. If pushing greater than 60g carbs per hour, it's probably ideal for glucose:fructose ratio to be closer to 1:1, rather than 2:1.

Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
-------------------------------------------------------------------------------------------------------------------------------------------------
📱 Check out our app → Saturday: Pro Fuel & Hydration, a performance nutrition coach in your pocket.
Join us on YouTube → Saturday Morning | Ride & Run Faster and our growing Saturday User Hub

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [ericMPro] [ In reply to ]

Nov 14, 20 14:13

Post #33 of 41 Views: 1525

These are two graphs from a performance diagnostics (spirometry): the left from a beginner, the right from a trained person.
The yellow curve is indicative for fat burning, the blue for carbohydrate burning.
At such a performance diagnostic, you push harder in time, e.g. in 3 minutes intervals.

As you see, at a certain intensity you do not burn any fat anymore, but only carbohydrates.

So I would not subscribe your assumption that "you're never not burning fat". Unless me, or the people who make them, do not interpret those graphs the proper way.

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [longtrousers] [ In reply to ]

Nov 14, 20 14:25

Post #34 of 41 Views: 1517

longtrousers wrote:

These are two graphs from a performance diagnostics (spirometry): the left from a beginner, the right from a trained person.
The yellow curve is indicative for fat burning, the blue for carbohydrate burning.

Any chance you can zoom in on each graph and repost for a clearer picture and discussion?

Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
-------------------------------------------------------------------------------------------------------------------------------------------------
📱 Check out our app → Saturday: Pro Fuel & Hydration, a performance nutrition coach in your pocket.
Join us on YouTube → Saturday Morning | Ride & Run Faster and our growing Saturday User Hub

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [DrAlexHarrison] [ In reply to ]

Nov 14, 20 14:56

Post #35 of 41 Views: 1501

DrAlexHarrison wrote:

longtrousers wrote:

These are two graphs from a performance diagnostics (spirometry): the left from a beginner, the right from a trained person.
The yellow curve is indicative for fat burning, the blue for carbohydrate burning.

Any chance you can zoom in on each graph and repost for a clearer picture and discussion?

I posted these graphs just to show my understanding that any spirometry shows that fat burning goes to null at a certain intensity. So it is not important for that to know the exact values in those graphs. These graphs show the different gasses you exhale which should be indicative to fat burning and carbohydrate burning. I'm far from being an expert and maybe eircMPro is right that you indeed always burn at least some fat, it only surprised me because I had an other understanding.

Last edited by: longtrousers: Nov 14, 20 14:59

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [longtrousers] [ In reply to ]

Nov 14, 20 16:44

Post #36 of 41 Views: 1471

longtrousers wrote:

DrAlexHarrison wrote:

longtrousers wrote:

These are two graphs from a performance diagnostics (spirometry): the left from a beginner, the right from a trained person.
The yellow curve is indicative for fat burning, the blue for carbohydrate burning.

Any chance you can zoom in on each graph and repost for a clearer picture and discussion?

I posted these graphs just to show my understanding that any spirometry shows that fat burning goes to null at a certain intensity. So it is not important for that to know the exact values in those graphs. These graphs show the different gasses you exhale which should be indicative to fat burning and carbohydrate burning. I'm far from being an expert and maybe eircMPro is right that you indeed always burn at least some fat, it only surprised me because I had an other understanding.

You are burning fat from the time you are born until the time you die and every nanosecond in between.

Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [ericMPro] [ In reply to ]

Nov 15, 20 1:15

Post #37 of 41 Views: 1412

ericMPro wrote:

longtrousers wrote:

DrAlexHarrison wrote:

longtrousers wrote:

These are two graphs from a performance diagnostics (spirometry): the left from a beginner, the right from a trained person.
The yellow curve is indicative for fat burning, the blue for carbohydrate burning.

Any chance you can zoom in on each graph and repost for a clearer picture and discussion?

I posted these graphs just to show my understanding that any spirometry shows that fat burning goes to null at a certain intensity. So it is not important for that to know the exact values in those graphs. These graphs show the different gasses you exhale which should be indicative to fat burning and carbohydrate burning. I'm far from being an expert and maybe eircMPro is right that you indeed always burn at least some fat, it only surprised me because I had an other understanding.

You are burning fat from the time you are born until the time you die and every nanosecond in between.

Here is another illustration of what I mean:

https://iconoclasses.com/...-maximal-effort-rer/

At the moment the respiratory quotient (RQ) = 1, there is no fat burning anymore, I quote from the beginning of that article:
"
A ratio of 0.7 is indicative of mixed fat use, whereas a ratio of 1.0 indicates the exclusive use of carbohydrates. Thus, during low- intensity, steady-state exercise, the respiratory quotient and the RER are typically between 0.80 and 0.88, when fatty acids are the primary fuel. As the intensity of the exercise increases and carbohydrates become the dominant or primary fuel, the respiratory quotient and the RER increase to between 0.9 and 1.0."

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [longtrousers] [ In reply to ]

Nov 15, 20 10:32

Post #38 of 41 Views: 1344

longtrousers wrote:

ericMPro wrote:

longtrousers wrote:

DrAlexHarrison wrote:

longtrousers wrote:

These are two graphs from a performance diagnostics (spirometry): the left from a beginner, the right from a trained person.
The yellow curve is indicative for fat burning, the blue for carbohydrate burning.

Any chance you can zoom in on each graph and repost for a clearer picture and discussion?

I posted these graphs just to show my understanding that any spirometry shows that fat burning goes to null at a certain intensity. So it is not important for that to know the exact values in those graphs. These graphs show the different gasses you exhale which should be indicative to fat burning and carbohydrate burning. I'm far from being an expert and maybe eircMPro is right that you indeed always burn at least some fat, it only surprised me because I had an other understanding.

You are burning fat from the time you are born until the time you die and every nanosecond in between.

Here is another illustration of what I mean:

https://iconoclasses.com/...-maximal-effort-rer/

At the moment the respiratory quotient (RQ) = 1, there is no fat burning anymore, I quote from the beginning of that article:
"
A ratio of 0.7 is indicative of mixed fat use, whereas a ratio of 1.0 indicates the exclusive use of carbohydrates. Thus, during low- intensity, steady-state exercise, the respiratory quotient and the RER are typically between 0.80 and 0.88, when fatty acids are the primary fuel. As the intensity of the exercise increases and carbohydrates become the dominant or primary fuel, the respiratory quotient and the RER increase to between 0.9 and 1.0."

RQ's in excess of 1.0 are possible during higher intensity exercise. 1.1 and 1.15 are commonly observed during VO2max ramp tests, and occasionally as high as 1.20. This onset of acid production and the resultant increased expiration of CO2 occurs before RQ=1.0, meaning that fat oxidation is still likely at RQ=1.0.

Tissue level acid (hydrogen ions) production increases as RQ approaches 1.0, and this increased acidity causes a shift in the bicarb buffering system, resulting more CO2 being breathed off, relative to actual carb use, before RQ=1.0 in a ramp test.

Therefore, RQ=1.0 likely indicates largely carb use, acid balance via respiratory system, and some lower-level fat use.

The "RQ=1.0 = exclusive carb use" is commonly taught in undergrad ex phys, and undergrad exercise physiology textbooks often contradict themselves (as is pictured here in Powers and Howley) in their pursuit of simplicity for the newer undergrad learners. I suspect that the "RQ=1.0 = exclusively carbs" argument is an oversimplification used to teach the concept of substrate utilization to undergraduate students in exercise physiology courses.

Completely shutting off the cellular machinery for fat burning in all tissues seems implausible and improbable. Reduced, yes, at highest intensities, and to the greatest extent in lesser-trained folks. (The bar graph image is a completely untrained subject with LT ≅ 60% of VO2max).

Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
-------------------------------------------------------------------------------------------------------------------------------------------------
📱 Check out our app → Saturday: Pro Fuel & Hydration, a performance nutrition coach in your pocket.
Join us on YouTube → Saturday Morning | Ride & Run Faster and our growing Saturday User Hub

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [longtrousers] [ In reply to ]

Nov 15, 20 10:36

Post #39 of 41 Views: 1339

With thanks to Powers and Howley, Exercise Physiology, Theory and Application to Fitness and Performance, 8th ed.

Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
-------------------------------------------------------------------------------------------------------------------------------------------------
📱 Check out our app → Saturday: Pro Fuel & Hydration, a performance nutrition coach in your pocket.
Join us on YouTube → Saturday Morning | Ride & Run Faster and our growing Saturday User Hub

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [DrAlexHarrison] [ In reply to ]

Nov 16, 20 3:20

Post #40 of 41 Views: 1273

DrAlexHarrison wrote:

longtrousers wrote:

ericMPro wrote:

longtrousers wrote:

DrAlexHarrison wrote:

longtrousers wrote:

These are two graphs from a performance diagnostics (spirometry): the left from a beginner, the right from a trained person.
The yellow curve is indicative for fat burning, the blue for carbohydrate burning.

Any chance you can zoom in on each graph and repost for a clearer picture and discussion?

I posted these graphs just to show my understanding that any spirometry shows that fat burning goes to null at a certain intensity. So it is not important for that to know the exact values in those graphs. These graphs show the different gasses you exhale which should be indicative to fat burning and carbohydrate burning. I'm far from being an expert and maybe eircMPro is right that you indeed always burn at least some fat, it only surprised me because I had an other understanding.

You are burning fat from the time you are born until the time you die and every nanosecond in between.

Here is another illustration of what I mean:

https://iconoclasses.com/...-maximal-effort-rer/

At the moment the respiratory quotient (RQ) = 1, there is no fat burning anymore, I quote from the beginning of that article:
"
A ratio of 0.7 is indicative of mixed fat use, whereas a ratio of 1.0 indicates the exclusive use of carbohydrates. Thus, during low- intensity, steady-state exercise, the respiratory quotient and the RER are typically between 0.80 and 0.88, when fatty acids are the primary fuel. As the intensity of the exercise increases and carbohydrates become the dominant or primary fuel, the respiratory quotient and the RER increase to between 0.9 and 1.0."

RQ's in excess of 1.0 are possible during higher intensity exercise. 1.1 and 1.15 are commonly observed during VO2max ramp tests, and occasionally as high as 1.20. This onset of acid production and the resultant increased expiration of CO2 occurs before RQ=1.0, meaning that fat oxidation is still likely at RQ=1.0.

Tissue level acid (hydrogen ions) production increases as RQ approaches 1.0, and this increased acidity causes a shift in the bicarb buffering system, resulting more CO2 being breathed off, relative to actual carb use, before RQ=1.0 in a ramp test.

Therefore, RQ=1.0 likely indicates largely carb use, acid balance via respiratory system, and some lower-level fat use.

The "RQ=1.0 = exclusive carb use" is commonly taught in undergrad ex phys, and undergrad exercise physiology textbooks often contradict themselves (as is pictured here in Powers and Howley) in their pursuit of simplicity for the newer undergrad learners. I suspect that the "RQ=1.0 = exclusively carbs" argument is an oversimplification used to teach the concept of substrate utilization to undergraduate students in exercise physiology courses.

Completely shutting off the cellular machinery for fat burning in all tissues seems implausible and improbable. Reduced, yes, at highest intensities, and to the greatest extent in lesser-trained folks. (The bar graph image is a completely untrained subject with LT ≅ 60% of VO2max).

Thank you for the extensive explanations.

Maybe we can agree on the following then:

"Fat use divided by carbohydrate use decreases with increased intensity but never goes to null because there always remains a certain minimum amount of fat use".

Re: >120 g/hr carbohydrate realistic? Discussion on MAX carb consumption rates during exercise. [longtrousers] [ In reply to ]

Nov 16, 20 8:49

Post #41 of 41 Views: 1219

longtrousers wrote:

DrAlexHarrison wrote:

longtrousers wrote:

ericMPro wrote:

longtrousers wrote:

DrAlexHarrison wrote:

longtrousers wrote:

These are two graphs from a performance diagnostics (spirometry): the left from a beginner, the right from a trained person.
The yellow curve is indicative for fat burning, the blue for carbohydrate burning.

Any chance you can zoom in on each graph and repost for a clearer picture and discussion?

I posted these graphs just to show my understanding that any spirometry shows that fat burning goes to null at a certain intensity. So it is not important for that to know the exact values in those graphs. These graphs show the different gasses you exhale which should be indicative to fat burning and carbohydrate burning. I'm far from being an expert and maybe eircMPro is right that you indeed always burn at least some fat, it only surprised me because I had an other understanding.

You are burning fat from the time you are born until the time you die and every nanosecond in between.

Here is another illustration of what I mean:

https://iconoclasses.com/...-maximal-effort-rer/

At the moment the respiratory quotient (RQ) = 1, there is no fat burning anymore, I quote from the beginning of that article:
"
A ratio of 0.7 is indicative of mixed fat use, whereas a ratio of 1.0 indicates the exclusive use of carbohydrates. Thus, during low- intensity, steady-state exercise, the respiratory quotient and the RER are typically between 0.80 and 0.88, when fatty acids are the primary fuel. As the intensity of the exercise increases and carbohydrates become the dominant or primary fuel, the respiratory quotient and the RER increase to between 0.9 and 1.0."

RQ's in excess of 1.0 are possible during higher intensity exercise. 1.1 and 1.15 are commonly observed during VO2max ramp tests, and occasionally as high as 1.20. This onset of acid production and the resultant increased expiration of CO2 occurs before RQ=1.0, meaning that fat oxidation is still likely at RQ=1.0.

Tissue level acid (hydrogen ions) production increases as RQ approaches 1.0, and this increased acidity causes a shift in the bicarb buffering system, resulting more CO2 being breathed off, relative to actual carb use, before RQ=1.0 in a ramp test.

Therefore, RQ=1.0 likely indicates largely carb use, acid balance via respiratory system, and some lower-level fat use.

The "RQ=1.0 = exclusive carb use" is commonly taught in undergrad ex phys, and undergrad exercise physiology textbooks often contradict themselves (as is pictured here in Powers and Howley) in their pursuit of simplicity for the newer undergrad learners. I suspect that the "RQ=1.0 = exclusively carbs" argument is an oversimplification used to teach the concept of substrate utilization to undergraduate students in exercise physiology courses.

Completely shutting off the cellular machinery for fat burning in all tissues seems implausible and improbable. Reduced, yes, at highest intensities, and to the greatest extent in lesser-trained folks. (The bar graph image is a completely untrained subject with LT ≅ 60% of VO2max).

Thank you for the extensive explanations.

Maybe we can agree on the following then:

"Fat use divided by carbohydrate use decreases with increased intensity but never goes to null because there always remains a certain minimum amount of fat use".

Agreed!

Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
-------------------------------------------------------------------------------------------------------------------------------------------------
📱 Check out our app → Saturday: Pro Fuel & Hydration, a performance nutrition coach in your pocket.
Join us on YouTube → Saturday Morning | Ride & Run Faster and our growing Saturday User Hub

Our Partners

transition-DOT-area-AT-slowtwitch-DOT-com

Advertise with us

©1999-2024 Slowtwitch, Inc., and Slowtwitch.com
Reproduction of material from any Slowtwitch.com page
without written permission is strictly prohibited.