Are your long runs easy or are you mixing in quicker pacing?

I don’t have any issues running 2 hours easy fasted sometimes with coffee prior.

It’s going to be trial and error figuring out what works for you. General rule of thumb has been every 5 miles or 30 mins for something longer than 90 mins.

Personally I'm going to carry two gels for a 2 hour run. I'll take one between 45-60 min and the other around 90 min (if needed. I don't always need it).
This will depend if you are drinking water or something with calories also.

I tend to think differently, and use my long run to practice my race nutrition strategy. I could do fasted / semi fasted, but I don't.

So this applies to my weekly 'long' run which does vary in length. I do a 16km/10km AM/PM day on a tuesday that I don't call a long run, but then the Sunday run is the 'long one'. That can be as short as 18km off season, or in a week following an event, or up to 33km. So anything from 1.5 to 2.5 hours.

Don't over think this. Easting is important for race day, so practice. So for me that's simply a case of some gu-chomps and a gel every half hour.

^ this - opportunity to test and train you race nutrition
also, while I can run 2-3 hours on water only, it will deplete glycogen and hurt my recovery and training for the next few days; so there's really not point in it

There are two sides to long run nutrition.

My feeling is that the majority of them should be with as little food as possible. You should be able to go 2+ hours or 18 miles without any calories if you are eating enough the day before. This also trains your body to use less fuel.

But, you also need to train with gels to get your system used to them. It can be beneficial to overload your body a bit on a long run or two to simulate race gut. Take one every 30 minutes for a 2-2.5 hour run.

FWIW, I did a reasonably hard 3 hour run yesterday on one gel and about 10 oz of water (it was around 50 degrees so not hot). I'll often go 18 without gels and about 50/50 on a 20 miler.

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speedySTATES

Trial and error.

I'd take a few gels or a sleeve of blocks or chews with me. Pop some about 1:10-1:30 into the run see what happens. Personally when I was doing long runs up to ~ 2:40 I'd have a clif bar with my morning tea and head out. Pop some blocks about 1:15 and again at 2h and call it good. Usually that worked now and then I was really thinking I could use a pepsi near the end.

As for practicing your race nutrition on long runs, sure that's fine once in a bit. Just remember race day is a different ballgame. You're starting the run dehydrated which should mean your first thought is to your stomach osmolality. It's an apples to oranges type of thing.

Your stomach is going to typically be much more tolerant of whatever you throw in it on your long run vs race day.

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From everything I read/heard (and I'm not claiming to be an expert), there's very small benefit to "running low" to train for fat burning.
Its really a lot more about the intensity being low so that your body doesn't switch to burning carbs (its a continuum not an on/off, but it becomes steep towards carbs very quickly).

So I would argue that the benefits of training race nutrition and not going into metabolic hole outweigh the fat burning training. But again, just my 2c, not an expert.

We're not robots, so it depends.

I always do my long run less than 2 hours after eating my breakfast (oatmeal, fruit, coffee, kefir), so I'm still digesting a bit.
I'll have a piece of nutrition about 60-75min in like a package of shot blocks, or a Lara bar.

I did a 6 hour trail run last year and did 1-2 pieces of nutrition per hour. Some people can take in a lot more, but I'm relatively light (142lbs) and my stomach can't take it.

I've been doing a few long trail runs over the past few weekends- 2-3 hours, largely in mid Z2 with a couple short pushes up hill (so nothing too intense). Running can be tricky because I find that my body stops metabolizing calories or liquid once I start running at threshold, which leaves me prone to side-stitching (especially on steep downhills). But on the flipside, I have no problems eating a lot of solid food at those lower intensities (I did a self supported 40 mile ultra last year with the same approach).

I much prefer to fuel with real food (e.g. bars, nuts, trail mix, etc.) than gels and drink mix when I have the chance regardless of sport (races I will use the sports nutrition to max performance). On long Z2 runs, I like to combine quicker digesting carbs with slower digesting fat, which I find gives me sustainable energy and helps me continue to burn fat and not carbs. Some of my go to foods are Nature's Bakery fig bars, Belvitas, or clif kids for easier digesting carbs, RX, clif, or larabars for medium digesting fat + carbs, and kind bars or Costco's cashew clusters for slower digesting fats. I try to take a bite of a bar every 10-15 mins and alternate the slower digesting with faster digesting. In total, I'll aim for about 200-250 calories per hour (or ~1 of these bars), which I find keeps me satiated with just a little bit of hunger. It's less of an issue in the winter, but I will try to follow-up each bite of a bar with some water with unflavored electrolyte drink. In cold temps, I drink probably 250ml/hour, but will aim for as much as 3x that in the hot and humid summers we get in the south. Last weekend, I felt like I could've kept running all day, even after 3 hours and 2500ft of elevation gained. Legs had no problem turning around for 2 hours total at 90-92% FTP on the bike the following day.

I have found as well that running goes much better when I don't fuel too much before, as I don't like food bouncing around in my stomach (and it makes it easier to eat more while running to lightly fuel before). The last couple weekends, I have eaten a bagel or artisan roll with cottage cheese and berries + a banana, for about 300-400 calories total an hour before I start running. The harder I am going to run, the less and further out I want to eat from the start of the race.

That's not to say what I do is perfect by any means, it's just what works well for me. I know that I tend to gravitate towards real food much more than other people, but to be honest I just don't like gels and drink mix and much prefer to eat RX bars and clif bars (the iced gingerbread clif kid's bar is heavenly btw). I also find that eating more balanced provides me with longer lasting energy and that I naturally eat fewer calories, compared to the science of 60-90g carbs/hour. Now that said, I'm going to experiment with pushing up my carb intake through race nutrition in advance of my 70.3 and long cycling races later this year.

I'm going to chime in and add a +1 for this approach. I'll bring 400 cals of drink mix and 3 gels over the course of a 2-2.5 hr run. Two reasons I do this:
-Prepare my stomach for race day in terms of how quickly I can absorb calories
-not feel absolutely bonked afterwards and the next day. I'm a parent of 2 young kids and I'd like to both be functionally present afterwards and be able to execute another run or bike the next day.

On a long run I just bring enough gels to consume one every 30 minutes +1 in case I feel like crxp.

So for 2 hours I bring 4 but probably consume 3.

When my training runs get up over 2 hours, I carry along some food (gummies, potato chips, shot blocks, whatever). If the run is only going to be a little over a couple hours, I hold off on eating until later (because sometimes I find that don't need to eat). If I know for sure that I'm going to be out 3-4 hours, I'll start taking in calories (smaller doses) earlier and more often, because I know that I will need those calories, and my body won't want to process a bunch later on.

That's a good point I have 3 kids under 6 who are.....active. Its rare (impossible) to get home after a run and get to flop on the sofa.

Lot's of food for thought here, I think based on responses, it's a personal thing. It's interesting I posted a similar thing on a British climbing forum (but also frequented by lots of hillrunners) and I think the feeling there was majoritively don't eat, whereas here I think it's maybe pushing towards eat/gels.

Can anyone point me towards any good reading on this?

Just a point, there's also some consideration of the 'people' bias there. Here, there's a mix, but biased towards the FOP/MOP multisport with a bias for strong cyclists* and with some degree of OCD re training - The russian from Rocky 5 would be laughed off this forum for being so lax with his training regime.

As opposed to a UK fell running forum, where they are still undecided on using rubber soles and not hobnailed boots, hydration is a cup of tea boiled on an open fire back in the hut, and they have a body morphology medically classified as 'gollum'. If they ate a chomp you'd be able to see the lump as it moved through their body for the next 8 hours.

My point being, different things, different people.

Regarding the reading, Angela Bean's Guide to Sports Nutrition is a great first book that doesn't just cover this, it covers pretty much the full range of sports nutrition as you'll need, covers some of the discussions / styles / myths too, so you can understand why people go for them, and why others oppose them.

One other question from me. Why wouldn't you want to eat? As in what's your goal from your training, as based on my approach to balance and sustainability in training then eating sensibly before, during and after is important. And to get to 'race weight' it's not what I do when training, it's little tweaks at other times in the week.





*suspicion, Dan may have the data, but my guess is this based on the forum discussions.

For a slow/steady training run longer than 1.5 hrs I steal some of my kid's welch's fruit snacks. The little snack packs have around 12 fruit gummies in them, I'll usually eat half a package at a time. Two little packets are more than enough for 2 hrs.

Haha! I use the same Welch’s fruit snacks on my long runs!

Typically nothing for 2 hours, maybe water if it's really hot (90F+). If I'm getting ready for a race then I'll practice/test my race day nutrition plan a couple times. Everyone is different though and I've been running long distances for a while so my body is probably more adapt to the training than someone new to the sport.

On my last long run, which was 18.5 miles and 2.5 hours, I burned 1,800 calories. I started right after a breakfast that consisted of a bagel and a yogurt, then I ate a Gu every 40-45 minutes, which is about 400 calories total. I got another 300 or so from Gatorade. I can handle Gatorade and Gu together so long as I'm going slow. In a race, I'll take Gu with water. I got another 300 calories from an Infinit Recovery mix immediately after I finished. I did not replace all the burned calories, but got a decent chunk of them back during and right after the run.

My aim in any long run is to keep myself fueled so that I stay strong the whole run and hasten my recovery. I'm probably doing another workout the next day, so replenishing is important. I generally don't think about fueling while running until my runs approach two hours.

For me it depends on the intensity of your long runs. I can run for 2hrs at low intensity on a fasted state and no calories. But if I increase my intensity I start to bonk. I eat a gel and problem solved.

To get my stomach to used to gels I use them on my long brick runs which I do close to threshold. I treat long brick sessions as race simulation, including what I eat for breakfast and during exercise.

For this of you who want to eat something different than the typical breakfast or gel try Nooty, an almond butter with protein plus simple and complex carbs http://www.verynooty.com

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http://www.verynooty.com

Everyone is different so it’s good to test out what your body prefers ... some can feel sick with food in the stomach and others can eat a pizza and whopper while running. Some ppl don’t like gels (like me), others live off it.

My strategy for 2+ hr runs is to carbo load the night before (esp for runs longer than 3+) and will also carry small snack bars .. protein, granola or snickers (my body is fine running and eating these). I also have a small bowl of yoghurt and muesli and can run pretty much half an hour after eating ... other times my body is fine with cookies, muffins etc.

Do you run with a vest? That makes it easier to carry food .. I tuck a banana in there, brownies, the fridge haha

If I do a long run on an empty stomach I bonk ... so have got to have my food intake and supply well organised.

(With the amount of food I eat, luckily my parents ... bless their hearts ... didn’t give me the fast twitch genes but gave me very good metabolism, so in no way would I encourage you to follow me if you are gaining 10 pounds doing so)

Actual science says: Way more carbs and sodium than virtually everyone here is mentioning.

Can totally get by on less for sure.

If you want to perform well, more is better.



Agree! But I think we can start higher than ~30g carbs per hour for optimal performance for 99.9% of athletes.

Hope the below helps a bit:

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Just an example:

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Interesting study. Points to 1:1 glucose:fructose ratio being pretty close to optimal. I suspect more will soon as well.

Fructose-Glucose Composite Carbohydrates and Endurance Performance: Critical Review and Future Perspectives

From that article:



Another interesting one:
Review: Glucose Plus Fructose Ingestion for Post-Exercise Recovery - Greater than the Sum of Its Parts?
From that article:


And another one pointing to utility of very high mixed sugar carbo oxidation rates as exercise exceeds 2 hrs:
Fructose and Sucrose Intake Increases Exogenous Carboydrate Oxidation During Exercise

From that article:

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https://www.semanticscholar.org/paper/Sports-Drink-Intake-Pattern-Affects-Exogenous-Mears-Boxer/42ffc8642ff5af57f2d047f363356fdcbb9efa9f
Key point to OP: Fueling every 5 or every 20 minutes appears okay while running, at least while only targeting only 100g carbs per hour and 1L of fluid per hour.

My comments here may be helpful too.

This forum is awesome and I feel like I'm finally with my people! Except... globally...please all start consuming more during training. You all might be faster. You'll almost certainly never have to feel like you "want a pepsi" during training.

If you are hungry or craving something specific during racing or training, you are WAY behind your intra-workout fueling and as far as your performance is concerned, it is an emergency.

Here is why it's an emergency:
Imagine being in a haunted house and having just been scared so much you jumped and your skin tingled. I doubt your next thought was, “I’m hungry.” Hunger was the last thing on your mind because the body has advanced cellular and hormone signaling that is designed to strongly inhibit hunger during times of “fight or flight.”
The strongest of which is epinephrine.

Epinephrine is also released during exercise because it is responsible for many of the cellular cascades resulting in energy availability.

If you sense hunger during prolonged exercise, it is because your hunger signals are so overwhelmingly strong that they have overpowered the extraordinarily strong hunger-inhibiting effect of epinephrine.

This only happens when you are lightyears behind on intra-workout fueling.

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Thanks for that, it's a truly super answer and one I appreciate you taking the time to post.

One of the responses I've read a lot is "it depend on my pace....if it's easy I'll go 2-3without fuelling, but pushing harder maybe a bit of food".

Is there any difference in the amount of fuel to take on board dependent on exertion? Or is it more a case of just load up because it takes a long time to get into the body?

I think the takeway from this for me is to fuel my runs for better activity and recovery.

My pleasure.


Short answer: Not necessarily, sometimes yes, but not as much of a difference between nutrition for hard vs. easy efforts as in the oft-cited all-or-nothing approach.

Longer Answer: If the run effort is easy, you can get away with not fueling better. Your HR and RPE will still be higher, per pace.

If the run is harder always fuel maximally for maximum performance.

You're just more likely to personally notice the consequences of not fueling adequately which is where this recommendation comes from.

Increased RPE is a lot more noticeable when moving from an 8 to a 9 RPE as compared to moving from a 4 to a 5 RPE.

The only good reasons not to fuel longer easy activities:

1. Efficiency. ie. your time is more valuable than your performance long-term.
2. Need for fat loss and you've already stripped out kcal from the rest of your day, so the easiest way to pull daily kcal lower is to short intra-workout fuel by 25-50%. Double-edge sword alert! Hypoglycemia is strongly hunger-promoting and strong hunger doesn't bode well for daily kcal deficit adherence!

The only good reasons not to fuel longer not-easy activities:

1. Efficiency. ie. time more valuable than performance.

Biggest negatives of not fueling easy long runs:

1. Lost opportunity to train gut to intake higher carb amounts in racing, which would otherwise be performance-enhancing.
2. Easy runs are no longer as easy on your body as they were supposed to be.
3. Decreased ability to utilize either endogenous or exogenous carbs in future. (ie. you get what you train for, carb burning, or fat burning in absence of carbs. Can't have both, and carb burning for performance wins.)
4. Muscle loss.

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Again many thanks, fascinating response, its great to have someone with passion and expertise talk about this.

If there is this science backing up constant fuelling, why aren't more people doing it? Is this new thinking or are people just stuck 20years ago with their sportscience? Somebody on another forum told me to read Noakes Lore of Running which is 35years old, is it just a case of it takes along time to filter into popular consciousness?

Agreed. Folks are just running calculated tradeoffs too. It takes some input of personal time and energy to fuel well. If you've got a spouse who wants to spend time with you or a job/business that is pulling at you, and you CAN run your long run with just a bit more fatigue without carbs... well, I do that all the time! Not optimal at all, but optimal for life happiness and financial well-being given the time-cost for sure. ;)

The performance improvement and RPE and HR reduction is quantifiable, even within-session. Just small effect within session. Almost certainly would be quantifiable in a more meaningful performance way if studied long-term. Feasibility of long-term study for something like this is.... challenging, to say the least, from a poor researcher's perspective.

NIH doesn't give grants to optimize the pointy end of endurance performance. They give grants to research prevent diabetes... which just exercising more is fine for! Sport nutrition research grants' dollar figures are <<1% of common NIH grants. I'll be impressed with the resolve of any researcher who chooses to study the even medium-term training adaptation effects of higher carb fueling.




You're very welcome. I'd love to spur some change.

There have been other areas where a certain piece of info becomes "common sense" before it's actually been well-tested. Low-rest hypertrophy training was touted as the gold standard in muscle building for a long time because of a (meaninglessly transient) bump in testosterone after performing such a lifting strategy. The testosterone bump does indeed exist. Just not sufficiently to merit low rest intervals in the weight room all the time for maximizing muscle growth. When weighing all thing tradeoffs it becomes infinitely clear that longer rest between weight room sets is better for strength and muscularity, long-term. But that took almost 15 years of a few sport scientists like me shouting from the rooftops to overcome because the low-rest recommendation had made it to the textbook level... primarily because the leader of the low-rest movement had written a book on it, and was also head of the NSCA at the time, the publisher of the main strength and conditioning textbook used in all college courses on the topic.

The current sticking points in exercise fueling nutrition dogma vs. science and press, as I see it:

1. A few leading researchers who first discovered that 90g carbs of multiple sugar sources was better than 60g/hr, got their work into every nutrition journal's position stand, subsequently into all the textbooks, and then amplified by every nutrition certifying agency and supplement company who seized the opportunity to sell more sugar when "90" became the new "60." Now 60 & 90g/hr are cited, rote, with no further thought.
   
   
2. Primary reasons researchers don't question the 90g/hr:


1. There was a single study that found that 30g/hr of fructose was the limit for fructose absorption during exercise. Turns out, fructose by itself is not absorbed well. When it's consumed with a glucose source, fructose absorption can far exceed 30g/hr, and I suspect may approach 80-90g/hr in a very well-trained gut.
2. 60g/hr glucose, in isolation also appears to be a bit of a hard limit before GI distress results. I think this may bump up closer to 70-75g/hr in well-trained guts, of regular exercisers, when consumed with fructose
3. The above two facts are probably recent to within the last 10 years or so, and most of my colleagues who I would consider experts in general sport nutrition, but not endurance nutrition, are surprised to learn of it when I point it out to them.
4. Most sport science researchers are young. They are within 10 yrs of having graduated with MS or PhD. Folks gravitate towards more complex and more clinical questions as they age as researchers. 60 & 90g/hr is the dogma taught in virtually all undergraduate and masters nutrition, dietetics, and exercise science programs, even some leading sport science programs. I don't blame them. Endurance nutrition is a bit of a niche and unless you've experienced suffering during long
5. Most studies only examine 1.0-2.5-hour exercise tests with maybe 3 hours being as long as any research has time to study. The difference between 90 and 130 grams of carbs per hour is likely amplified only beyond about 3 hours. It's very hard to carry out studies that involve 4-hr time or 5-hr time trials. No one has time or interest in killing themselves for 4 hrs multiple times for science because it interrupts their training process. Even fewer (none) researchers want to carry that out because of the time-cost involved!
   
   
3. Primary reasons lay-people and athletes don't question the 90g/hr:


1. Most folks can't even figure out how to do 90g/hr because they're messing up osmolality and hydration needs. Gotta have hydration, and with fluid you gotta have sodium. Miss out on sodium and you're going to get sweet aversion and performance-relevant hyponatremia and avoid the 90g/hr. Miss out on fluid and you're going to get gut cramps or worse downstream GI effects, from even 90g/hr. Lots of folks report "a gel doesn't sit well with me" because they don't drink water with it. Most folks could take 3 gels at a time with 16-20oz water on an empty stomach in the middle of a hard session and fair okay. They fail to do the water with it. When there are so many hurdles that are lost on the average person, it's easy to believe that 90 is the top when there appears to be mountainous social proof that corroborates.
2. The fat adaptation movement which I hope has been quashed has intensified any subconscious thought that maybe less carbs is better and so I don't always need to train with them because there may be a benefit. There is not. See my other recent posts for more there.
3. Most folks don't train more than 2-3-hr sessions where you CAN get by on less. If you're routinely doing 4-6-hr sessions or racing 4+ hrs, there will be noticeable difference in performance. This makes basically ultra-runners, P/1/2 cyclists, and 70.3 & 140.6 triathletes the only folks who are ever likely to investigate enough personally, to notice a difference.

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Here's my very niche n=1 story:
After doing tri for 11+ years and LD for 9 of them I was diagnosed with (late onset) Type I Diabetes last fall.

Since then I am wearing a continuous glucose monitoring device and have been able to monitor my current blood glucose level at all times. Obviously this has been very interesting, especially during workouts (I have a data-field on my garmin for that).
Knowing what I know, It is of no surprise to me that this very technology is beginning to get traction in performance application in elite athletes (e.g. jumbo-Visma).

Clearly my primary focus is managing my diabetes and still being able to do tri competitively.
Also my metabolic system is no longer fully comparable to that of somebody with a functioning pancreas.

That being said, I made a couple of observations:

• I usually have a sharp drop in blood sugar in the first ~30 minutes of exercise (probably diabetes related and not relevant to y'all)
• For Z1/2 endurance workouts like the long run, it then stabilizes usually just below the "normal" level of 100 mg/dL (5.6 mmol/L) without any fueling
• Then however it ever so slowly and steadily starts declining so that within an hour at the latest I am seeing and feeling low blood sugar
• That's why i started to always run with a 140ml gel-flask and fuel pretty much from the beginning (unless I had a snack just before the run).
  (In contrast: In the past I followed the boosting fat metabolism idea and would only have maybe one or two gels if I felt hungry/bonkish 2 hrs in.)
• As a consequence
  


• my long-runs feel much better,
  
• I can hold better technique for the full duration
  
• I am not as wasted afterwards.
• pace-to-heartrate ratio is getting better (see graph below)
  
  
  
• If I fuel till the end of the workout, my blood sugar starts rising pretty sharply after I stop running


• I need to be weary of this and correct with insulin,
  
• But I guess for the healthy person it means that your in-workout fuel will also "be there" for you for recovery after the workout.
  

In terms of what goes in my gel-flask i am still experimenting with various mixes of maltodextrin, fructose and dextrose with some citric acid and coke-flavour sirup for taste.
Going by the info in this thread I should apparently be looking into getting to a 1:1 Dextrose:Fructose ratio...

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if you can read this
YOU'RE DRAFTING!

This is a fantastic case study. Thank you for sharing. Most of it is highly relevant to folks without Type 1 diabetes.
The sharp drop in first 30min is relevant and probably common among folks with no diabetes. Probably related to GLUT4 translocation, but maybe other things too. https://journals.physiology.org/...2/ajpendo.00503.2020

This is actually all quite relevant and standard physiology for folks without Type 1 diabetes. I have suspected for a while, though I have no data on it other than yours, that during exercise is the time that folks with Type 1 diabetes metabolism tends to look most like the metabolism of folks without Type 1 diabetes. Just hasn't been a focus of my research yet. I may ask my wife who is an RD, triathlete/cyclist, and diabetes-interested.
100% correct. This is where your physiology starts to differ a bit from other folks who probably wouldn't have quite as steep of a rise or need to correct with insulin. My wife has often joked that there is a performance-enhancing opportunity for endurance athletes with Type 1 Diabetes if they're smart. (ie. pack in carbs for recovery faster.) Please take this as purely academic discussion and chat with your physician! I am not a medical doctor. :)

Yep, definitely closer to 1:1 than 2:1.


Sugar ratio change implications, during exercise: If you go to more optimal sugar ratios, absorption rate can be increased, which may elevate blood sugar marginally during training (a good thing), but also makes intaking the sugars at a higher rate per hour more optimal because there is less measured titration of the sugar from GI tract to bloodstream. For folks without Type 1 diabetes, and I suspect for you too, this means that if you were to NOT increase from your current consumption rate intra-workout, you may experience slight sugar crashes if there are 20-30min gaps between consumption. Recommendation: consume more. Consume steadily.

Sugar ratio change implications, after exercise: For you specifically, this may also merit closer monitoring of blood sugar rise post-workout until you have done further experimentation.

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📱 Check out our app → Saturday: Pro Fuel & Hydration, a performance nutrition coach in your pocket.
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Wow I have been doing a base training cycle and bumped up my mileage the past 12 weeks into the 60 mpw range which means (with all easy running) I've been doing multiple 2+ hour runs per week. The only intensity in them has been strides and/or some short fartleks. Right now I just take a few swigs of water every 30 minutes. After reading through this thread I guess I should start looking into taking in some carbs especially as I move toward 3 hour runs and begin working some longer periods of intensity in. I've never done this kind of mileage before and didn't really think about fueling at all (I do usually eat some carbs before I head out on my run though so maybe that has been enough). Thanks for sharing your knowledge!

Why does the g/hr recommendation reduce back to 90 for workouts greater than 6 hours? As an ironman athlete, how should that effect my nutrition plan. I thought the goal would be to take in as many grams of carbs as your gut can handle.

This is just anecdotal but I think there's a couple reasons runners in particular don't fuel their workouts as much as triathletes or endurance-oriented cyclists.


1. Distance- For non-ulta runners, a 90-120 min run is a "long run." Even if you run that hard, you can generally just consume some fluid and maybe a gel or some drink mix and be ok at the end. You may deplete your glycogen stores, but are less likely to bonk while actually running (and your glycogen will replenish before your next workout, so you may not know how far you've depleted your glycogen).

Now compare that to a 4+ hour triathlon or cycling event, and there's no way you can go that long without fueling unless you're fat adapted or performing at a very low intensity. Ultra runner get this- look at what they eat during 50-100 mile races. Candy, chips, pizza, literally anything and everything they can stomach. But someone running at most 2 hours will never be in the same boat as someone hour 4 into a long event.


2. Ability to fuel- It's a lot harder to fuel when running than cycling- harder to carry food/nutrition, and harder on the body to absorb. I can eat and drink pretty much anything at the bike, but once I start running at threshold, I can only tolerate little bits of liquid before I become prone to stitching (especially on hilly courses, running hard downhill really gets me if there's anything in my stomach).

To that tune, I would argue it's performance maximizing to not fuel short races. A 5k or 10k isn't going to be faster if you take a gel during, and if you're on the limit, you're more likely to risk gut distress than anything. Due to my issues with stitching above, I don't fuel any run <90 mins except with a couple sips of water/gatorade at aid stations (more water plus salt tabs if it's hot). I would actually prefer to be slightly hungry at the start of a really hard run because I know there's nothing in my stomach to cause issues (I know that's contrary to the science, but I've run my best races this year across every distance with this approach). Meanwhile I would rather start long cycling races slightly full because I don't have distress fueling on the bike.

Great question: hydration becomes so critically important for longer events that it trumps optimal fueling needs. Consuming 120g/hr sometimes marginally slows gastric emptying and ability to hydrate. If you know for sure that you're able to maintain 99% of your body weight during very long sessions via adequate fluid and sodium intake, then you can certainly continue to push the higher rates of consumption. Best way to find out. Try it. If you don't get gut cramps or GI issues doing >100g/hr in an 8-12hr event, then by all means increase carb consumption rate to 110 or 120g/hr and give it a go. Could also taper carb consumption rate throughout the event from something like 120-140g/hr at the outset down to 80-100g/hr when gut issues start to sneak up on you. The more practice the better, obviously.

In all honesty, I'll probably update that when I write v2 of the book. I think it can be pushed to 120 or 130 if in cooler temps or for a person who is a very limited sweater. Book was written a couple years ago. v2 is a couple years away. Other projects in the works first!

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Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
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Agreed on all.

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Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
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📱 Check out our app → Saturday: Pro Fuel & Hydration, a performance nutrition coach in your pocket.
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Good question, and a common one!

Once fitness is sufficient to burn 600+ kcal per hour, as you mention, I see very little reason to fall below recommended values. Gut tolerance should be your only determining factor. Fuel maximally, within that.

Gut tolerance is minimally related to bodyweight, fyi.

My wife weighs 63kg roughly, and frequently consumes 100-135g/hr on the bike, and 80-100g/hr on the run. For her, I'm not convinced there's much benefit over 80g/hr running, because of gut issues. On the bike though, we've yet to find a tolerance upper limit or utility upper limit. The more the better, in her case.

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Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
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📱 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

Thank you- this is all very helpful. I have a couple months training left and I will experiment to see if I can increase my intake to at least the recommended amount without putting too much stress on my gut.

Kipchoge says you should only run for 1:59

OK all kidding aside lots of great advice on this thread. But I would say more people should be more worried about weekly aggregate mileage than with length of long run. 100km run with with a 2 hrs long run is likely going to be much better than 60km run week with a 3 hrs long run. Mileage is king, long run is less important if you have mileage to handle your race day.

in the 1980s, after the Leppin Squeezy came out as the first gel (based on Dr Tim Noakes research), I used to run with a chemist developing a competitor gel. His research showed a mix of glucose/fructose was more effectively absorbed than either alone. I'm not sure what happened to that product or if it even made it to market..

Arthur Newton was a great ultrarunner in the early 20th century. He developed the 'corpse reviver', a mixture of lemonade, bicarb, sugar and salt, for his long training runs for Comrades marathon (about 55 miles).
Turned out the mixture was isotonic and well absorbed..

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We're forgetting-machines. Men are things that think a little but chiefly forget. That's what we are.
- Henri Barbusse

Gold quote.

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Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
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📱 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

Completely agree,m winter and spring for me are all about metabolic efficiency and fat adaptation, plus high quality real food (and usually some fat loss). Close to race season, it's all about training the gut to absorb simple sugars under stress/duress/race intensity, so i definitely start to mimic race fueling strategy in training.