Endurance Skating

Training, Racing & LCHF Fueling For Skating And Endurance Sports

Race Fueling Part 2 – Carbohydrates

Recap In-Race Fueling Part 1:

  • Racing Is Not Training – In a race the aim is to perform to your best, not to train for adaptations. Your fueling strategy should reflect this truism.
  • Calculate your expected energy expenditure and have an idea of your personal fueling equation
  • Prioritize replenishing glycogen and protein, your fat stores are already plentiful, and your ability fuel from fat is already predetermined by your day to day nutrition and training; endogenous fat consumption will do very little to change that during the course of a race.
  • Use whatever in-race foods and supplements you find work for you!


Now I’ll delve a little further into race nutrition and write about what I typically use in long races.  While I have basically said that “anything is fair game” when it comes to race fueling, I personally still try to stick to “real” foods as much as possible… I seriously can’t remember the last time I used an energy gel or a garden variety “sports drink”.


Understanding Different Carbohydrates

There is a lot of confusion and misinformation surrounding how we think about carbs. As an athlete it’s to our direct advantage if we understand the different types of carb sources, and how the body processes them.

To understand carbohydrates better and how our bodies make use of them, we can classify them according to their molecular complexity, as follows:

Simple Sugars – in chemical terms these are also known as monosaccharides – as their name suggests, they exist as a collection of singular, unbonded & unattached carbohydrate molecules. Ripe fruit, vegetables & honey are examples of sources of monosaccharides. Monosaccharides are readily digestible by our digestive systems.

Double Sugars – aka disaccharides, these consist of two joined carbohydrate molecules. Table sugar (sucrose), milk (lactose), maltose, maple syrup and many of common things that we think about as “sugars” are double-molecule disaccharides.

Complex Carbohydrates polysaccharides/oligosaccharides, as their name suggest, consist of many – potentially thousands of – carbohydrate molecules joined together. These are also known as starches. Potatoes, all grains, and legumes are good examples of complex carb sources.  The maltodextrin that is commonly used in 99% of all sugary sports drinks is a polysaccharide with a chain length between 2-20.

Types Of Carbohydrate Molecules

Adding another layer of complexity, there are several different types carbohydrate molecules that we must consider. The importance of the distinguishing between these is that our bodies have different digestive enzymes and metabolic pathways for these different monosaccharides.

Carb molecules


Glucose – is the carbohydrate molecule that is the body’s preferred energy source. Muscle glycogen is technically a polysaccharide chain made by your liver from the individual glucose molecules available to it.

Fructose – is the carbohydrate molecule that is found in many fruits and vegetables. Fructose tastes sweeter than glucose, which is why it is used so abundantly in processed foods, however unlike glucose it cannot be used by the skeletal muscles and is instead metabolized directly by the liver; this makes its less valuable as direct source of energy for exercise.

Galactose – is the carbohydrate molecule commonly found in dairy and some other sources such as sugar beets. When someone doesn’t do well on dairy, it is commonly because they lack the enzymes required to digest and metabolize the galactose molecule.

Of these three, glucose is the most important and easily used by the body, with galactose being the least useful. Fructose can be useful in limited quantities. Because they are processed by different pathways, you can maximize total carbohydrate intake by ingesting a mixture of glucose & fructose and processing both simultaneously.


Mixing ‘n Matching

Now that you understand simple vs complex sugars and the different types of carbohydrate molecules, consider that most disaccharides and some polysaccharides are often composed of different types of carbohydrate molecules joined together…


  • Sucrose is a disaccharide composed of 1 molecule of glucose joined to 1 molecule of fructose
  • Lactose is a disaccharide composed of 1 molecule of glucose joined to 1 molecule of galactose
  • Maltose in beer, pasta, and malt-based foods is a disaccharide of two glucose molecules
  • Maltodextrin is a polysaccharide of between 2-20 glucose molecules only
  • Amylum is the chemical name for what we commonly call “starch”, and is polysaccharide of between 500-2000 glucose molecules.


High Fructose Corn Syrup is, perhaps surprisingly, similar to honey in that it is composed mainly of  single unbounded simple sugars fructose & glucose in a roughly 55%:42% split (no, I don’t know where the missing 3% is). Quite whether that implies that HFCS isn’t the evil that everyone has labelled it, or that natural honey isn’t quite the elixir of healthy carbs that people tend to associate it with, I am in two minds over… I suspect the sheer abundance of HFCS as a sweetener in every processed food in the supermarket (easily amounting to 20-40 teaspoons per day for most people) is the big problem; 20-40 teaspoons of sucrose or honey would be equally deleterious. FWIW I still tend to stay away from anything with HFCS with one exception, because to me it’s synonymous with “processed” food. More on HFCS later….


What All Carbohydrates Have In Common…

I have simplified this somewhat, and as you can imagine, it can get very complex when you consider what can be joined to what.

However, irrespective of their composition and molecular structure, there is a very simple biological fact that is inescapable: your digestive system must break down all complex carbohydrates into a simple sugar (ie monosaccharide) form, before they can be digested and metabolized for either energy or storage. Therefore, the more complex the carbohydrate, the more work your GI tract has to do to break it down and the longer it takes before it is available as energy.

Slow absorbing and fast absorbing carbs both have their pros and cons.  Complex carbs will provide a slow steady supply and help sustain fat burning, but can frequently cause GI distress if your stomach is unable to digest what you have thrown at it.  Simple sugars require no digestive work – they are freely available to use, however too much can cause a blood sugar rollercoaster.

.. And The Implications

Taking all this into consideration, I have personally revised my thinking about how to structure my in-race nutrition this year, and especially my thinking about my carbohydrate intake. Last year I was still prioritising fat (and protein) for in-race calories; going forward I will be adopting the approach I have outlined herewith – I guess I could call it my own interpretation of the OFM (Optimised Fat Metabolism) strategy.

Note: What follows is based on my current interpretation of “strategic” carb usage, and is very much a WIP!



72hrs ahead of race day – load with about 100g (15% total energy) intake of slow release carbohydrates. A few sweet potatoes in the late evening should do the trick, ideally I’ll “backload” these after my final pre-race training session. These will be digested and stored as muscle glycogen overnight.  A couple of hours with the Cool Fat Burner vest will really help insure that the glucose is pushed into the muscle. Hydration is also very important; I aim to drink plenty of WATER over the course of the day.

48hrs ahead of race day – continue loading with up to 150g of slow carbs, once again to be mainly eaten in the evening. Again, I’ll try to use cold thermogenesis and remember to drink plenty of water.

24hrs ahead of race day – go back to very low carb, 30g-50g. On this day the aim is to ensure maximum fat-burning while keeping my glycogen topped off… so I just eat – what is for me – normal!  Cold thermogenesis, check. Hydration, check.


So that works out to about 300g  (1,200kcal) of carbs front-loaded over 3 days, which is about 2/3rds of my body’s maximal carbohydrate storage potential.  This makes sense to me – at the beginning of the loading process, my carb stores will already be closer to “fully stocked” that they will be to being empty. Anything more is overkill – the aim is not to bump up my maximal glycogen storage potential as per traditional carb-loading, it’s simply to ensure that my existing glycogen tanks are close to fully stocked while not over-filling them and therefore downregulating my fat-burning potential.


Race Morning – Avoid any carbs pre-race. My body is already in maximal fat-burning mode when I awake, and the aim is to keep it that way up until I toe the start line. Note that taking a sugar-bomb in the form of sports drinks or gels ahead of the race start will absolutely inhibit your body’s fat-burning capability. Don’t make this mistake! Timing is everything now – save them for during the race, if at all.


Consider using slow-release carbohydrates nearer the start of the race. Your muscle/liver glycogen is are still well -stocked in the early stages, and your stomach is still firing on all cylinders. At this stage it is prudent to just drip-feed glucose into your system to keep glycogen levels high.


I start all my races on UCAN – a new so-called “superstarch” which is a unique carbohydrate with a molecular weight of 500,000-700,000 – hundreds of times larger than a typical matodextrin or starch molecule. The result of this is an ultra-slow absorption rate once the superstarch has emptied from the stomach into the GI tract, which keeps blood glucose stable and actually enhances fat-burning.


UCAN is a very popular and trendy race fuel for the high-fat endurance fraternity right now, and I don’t doubt that it fulfills its aim of a stable blood glucose, but I feel that its differentiating claim to avoiding blood sugar & insulin spikes compared to normal sports drinks is probably not accurate, as the insulin mechanism is inhibited during exercise – a fact of exercise physiology that probably needs a full post to dissect properly.

banana-smoothieAt some point, when UCAN gets too monotonous and if the race is long enough, I start introducing real food – as stated I try to prioritise them above matodextrin-based sports drinks and gels. I’ve never been a fan of gels, and would rather have something savoury to chew on if anything.

My favourite go-to at the moment is a banana & coconut-milk based smoothie, and Phil’s Bars. Just having these will get you through many a tough race!

While carbs from veggies are great on your normal dinner plate, they don’t work so well during a race because of the work required your system has to do break them down, thanks to the fibre content. I want fast absorption – that’s why I like blended smoothies!


I will switch to more simple sugars as the race progresses, so that my GI tract has less to do. I will use any of the following:


  • A Honey solution
  • Coconut water a trendy drink right now packed with a natural source of simple sugars and electrolytes
  • Fruit juices; grape juice & apple juice are good choices, but not citrus fruits which are too acidic
  • Coca Cola (full fat) is also a very plausible option, thanks to the simple sugars in it’s HFCS content.  Double Ironman world champion Chris McCormack swears by coca cola and/or Red-Bull!  I tend to save these for the last quarter of a race if I go there at all – you know by the time you are reaching for the coke that there’s no going back!

Whatever drinks I use, I try to aim for a 6% solution to keep them isotonic (ie similar to the body’s blood plasma concentration), so that the stomach doesn’t have to either dilute or draw water out of the drink to match body fluids.

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Basic strategy overview:

  • Carb “Sneak” 72-48hrs before the race, using slow-release complex carbs
  • Fuel with complex carbs once race is under way
  • If the race is long enough, prioritize real foods (but in easily digestible form) as the race progresses
  • Switch to simple sugars in the latter stages to give your body less work to do

Phew. We’re getting there…. as I said, this is very much a WIP.  I didn’t mean to focus on carbs so much when I started this “Part 2”, but  as carbs are often the elephant in the room for many LCHF discussions, I thought that it would be good to make clear my current thoughts on the correct and optimal usage of carbs for fat-adapted athletes.  The message is: moderate your carbs for the normal day to day for good health, but don’t be afraid to use them for racing!

In part 3 I’ll  tie up the last bits of my race nutrition in more detail with what protein & fat-based food sources I use, and talk about my current view on hydration & maintaining electrolyte balance, and what other supps I like to use for race day!


3 comments on “Race Fueling Part 2 – Carbohydrates

  1. jmthomson
    May 6, 2015

    A great informative post – thank you, very useful to my approach !

    Liked by 1 person

  2. jmthomson
    May 6, 2015

    Reblogged this on runs to stand still and commented:
    Excellent post about low carb running – highly recommended!


  3. Pingback: In-Race Fueling Part 3: Race Day | Endurance Skating

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This entry was posted on May 5, 2015 by in Food, Nutrition, Science and tagged , , .

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