High carb fuelling – a lengthy take!

Running goes through phases (and fads!) like everything else – remember barefoot shoes, beetroot shots, perfecting cadence and, more recently, bicarb, heat training, and high carb fuelling?  These things are not necessarily useless, harmful or wrong – but they highlight there are fashions in running like anything else.  Sometimes the fashions can be useful and informative, and sometimes they can be unhelpful at best or harmful at worst, depending on your physiology – not every trend will benefit everyone.

The trend I’m getting the most questions from my athletes about at the moment is high-carb fuelling.  This has been accelerated by increasing availability of different types of fuel – we are no longer limited to gels, but can choose from a wide array of bars, chews and drinks mixes.  Brands have also started producing specific ‘high carb’ options – see Science in Sport’s ‘Beta Fuel’ range, and the new Tailwind ‘High Carb’ mix.  Promotion by high-profile coaches like Megan and David Roche has also helped, and it’s increasingly common for runners to adopt the habit cyclists have had for a while of detailing the grams of carb they’ve ingested per hour during each event or training session.

 Let me start by saying that in general, I’m a big fan of this current focus.  The spotlight on high-carb fuelling has brought a welcome shift in the running community from seeing fuel as a ‘how little can I get away with’ game, to the opposite, ‘how much can I get away with?’  In general, I think that this is likely to improve performance, recovery, and overall health – whenever one of my athletes deliberately increases their fuel intake they invariably report a significant improvement in endurance during their event and recovery afterwards.  But I think it’s also important to consider the individual runner, and the specific event they are preparing for, when deciding how to fuel, rather than adopting blanket recommendations which may have been designed with someone very different in mind.

To give an example, Science in Sport state ‘Research shows that endurance sport lasting 2 hours or more requires 80-120g of carbohydrate intake per hour’.  This will be true, for someone.  Most likely, for several someones, somewhere, in a research study.  It might be true for us too - but to understand whether this is the case, we would need to know much more about who the study participants were – their gender, age, prior experience, training regime, the study parameters. 

What I want to do, therefore, is to try to unpack why, when and how to fuel, so that as an athlete you are better equipped to make fuelling decisions that are correct for you, for your body, and for your race.  One fuelling strategy will not serve you for every event, or even for the same event on different days; you need a repertoire of tried and tested options that you can tweak to suit each new challenge.

At the most basic level, fuel is required for movement.  If we want to move a lot, or move fast, or both, we need fuel.  The type and frequency of the fuel depend on the duration and the intensity of the movement.  There is, of course, an inverse relationship between these two – as the planned duration of your activity lengthens, the intensity at which you complete it will drop.  This will shift the balance of your use of the different energy systems in your body.  This is a complex topic, and could easily form an entire blog post.  But let’s keep it as simple as possible without being inaccurate – when you run at an easy intensity, your body is able to metabolise fat as fuel (although it’s also happy to use carbs), while at higher intensities you require carbohydrates to sustain this intensity.

At the short, fast end of the spectrum, I suggest that for a planned duration of 60-90 minutes, you don’t need fuel, even if you’re planning to run hard.  The body has more than enough stored carbohydrate to fuel this effort.  An exception might be (since, as we’ve established, fuelling is very dependent on the athlete!) if you are a seasoned racer planning to seriously push the pace – then a gel shortly before the start might assist.

Fuelling starts to become important around the two hour mark (by which I mean, if you are running a two hour or longer event, you should fuel throughout, not you should start fuelling after 2 hours).  If we’re talking about a race effort, you are likely to be working pretty hard, and you need easily accessible carbs.  These are likely to be most easily provided by sports food – gels, drinks, chews, bars.  We’ll unpack the reasons a bit more below, but these products are specifically engineered to deliver the largest amount of carbohydrate possible into your bloodstream, as fast as possible, ideally without making you feel sick.

The longer your event gets, and the easier the intensity becomes, the more your fuel can become mixed.  You don’t need the immediate availability of the engineered carbs in sports food; ‘real’ carbohydrates such as sweets, biscuits and sandwiches will become digestible.  At very long durations, including fat as fuel may be beneficial too.  Fat takes longer to be digested, so it’s not much help on a shorter event.  But if you’re intending to be out there for many hours, or even days, fat and protein are a great fuel source.  Creating a more diverse fuel mix also helps longer duration runners to avoid flavour fatigue and GI distress.  I ask my athletes initially to aim to consume 100 calories of food (mainly carb, either real or sports food) every half hour.  Once this is possible, we try to up the amount, by increasing portion size, increasing fuelling frequency, or adding other products (for example, keeping the solid food but adding a drinks mix).

Returning to the carbohydrates – let’s say you’ve established that your event is going to be short and intense enough to require a fully carbohydrate-based approach, and that you want those carbs to be very simple and easily absorbed.  Everyone is different, but a lot of people take 60g of carbohydrate per hour as a ‘baseline’ fuelling target.  If aiming to meet this target using sports food, most gels are between 20g and 30g of carb per gel, so are designed to be used either every 20 minutes or every 30 minutes.  One limiter on carb absorption is that above a certain level, the stomach’s ability to absorb glucose (usually the main component of gels) tops out.  Gel manufacturers circumvent this by adding a second type of sugar, often fructose; which allows the body to take in more fuel.  If you are working at a high intensity over an extended period, this is a genuine advantage of manufactured sports food over real food, which is hard (but not impossible) to replicate.  This is also where the new breed of ultra-high carb products come into play - Beta gels contain 40g of carb vs a ‘standard’ 30g, and High Carb Tailwind, depending on how you mix it, can deliver 90g of carb per 500ml of water vs the standard endurance fuel at 50g per 500ml.  The idea here is that by carefully adjusting the sugar type ratios, the manufacturers have created a way to persuade the body to absorb more.

The question is, do you need it?  My belief is that most of us don’t need the 80-120g of carb per hour from the Science in Sport quote earlier.  I suspect that these stats are based on elite, male athletes racing 2-3 hour events.  Me, and most of my clients, are non-elite, female athletes racing 4-24+ hour events!  So we don’t need to aim to take three Beta gels, or swallow 90g of Tailwind High Carb per hour.  I do think these products may have a role for us; if by concentrating the fuel more highly you are able to consume it more easily, that’s a benefit.  By which I mean, if you prefer to only take two gels an hour, rather than three, Beta Fuel makes that possible, but still delivers a similar overall fuelling amount.  One word of caution here: build up to these fuels and try them carefully in training!  Both brands recommend practising ‘gut training’ before using the products in races, which suggests to me that their pool of testers have had a tricky time adjusting to them.

I also often get asked whether it’s ok to use a different type of sports food from gels, usually because people either don’t like the texture, or feel ill having used them.  Consider digestibility again; as a rule of thumb the more chewing the product requires, the less quickly it will digest and make its way into your bloodstream.  I tend to use gels and drinks when I want the energy quickest, chews and bars when I’m happy to have it a little more slowly.  Additionally when you are working hard, your body is pushing as much blood as possible to your muscles, to deliver vital oxygen there.  This means less blood is available for digestion, and so the less complex the carb, the better.  The tasty bars that might work well on a training run may now be too much for the stomach to handle, and an easily-absorbed gel becomes a better option.  For this reason, I advise runners to test their planned race fuel on an interval session or two – can the body handle this fuel at a higher intensity than you plan to race at?  If so, there’s a good chance it will be happy with it on race day.

A final couple of factors - what you like is also important!  Don’t choose a fuelling product you hate because you think it will be more effective; you’ll probably just end up less likely to use it.  Consider also the electrolyte content – check whether your chosen fuel also contains electrolytes, and if so, how much?  You’ll need to factor this in to whether you also choose to take any stand-alone electrolytes.

If you are despairing from a budget perspective (lots of gels come in at around the £2 mark, a quick calculation on a napkin suggests that to fuel a full marathon training cycle on gels would cost £100-£150, and an ultra training cycle even more; it’s a significant investment).  Remember too that if you’ve seen a gel or another fuelling product being promoted on social media, there’s a good chance that the person extolling its virtues has been paid to do so, or at the least has been given the product for free.  There are ways to get the fuelling benefits of manufactured gels without the cost.  Some athletes have gone down the line of mixing their own gel!  Maltodextrin, glucose and fructose can all be bulk bought online; some people also add gelling agents and/or flavouring, and if you’re not fussy about texture, this would be a highly cost effective option.  A newcomer to the gel market is the very popular Protein Rebel maple syrup gel – but on noting that the gel has only two ingredients (maple syrup and salt), a client of mine simply bought a gel flask and a large container of maple syrup!  Maple syrup is a good option, as it contains a mix of sugars: mainly glucose with some sucrose and fructose.

Even considering all of the above, the majority of athletes I coach (and me, too!) don’t need to make their own gels, or bulk buy maple syrup.  We’re mainly training for longer events, where a more balanced intake is better.  To give an example, my personal fuelling for a 5-6 hour hill run at an intensity between RPE6-7, I would use a mixture of biscuits, sweets, and some manufactured options (my personal choices are VOOM bars, Tailwind drinks mix, and Gu gels, none of which I am given for free).  I use these products sparingly, because they cost more money than biscuits!  But I have never felt that my training or racing have been impacted by a fuelling strategy that leans heavily on Oreos and Skittles.

Ultimately – remember it’s personal.  Your optimal fuel mix depends on your race duration, your planned intensity, your personal preferences, and your stomach’s ability to digest what you’re trying to put in it.  Try different options, and don’t feel that any/all of those options have to be manufactured products.  If you’re coached, chat to your coach (if it’s me and we haven’t talked about fuel, talk to me!); they will be able to help you work out how much fuel you need, identify solutions, and troubleshoot any issues you’re having.