Fuelling for optimum performance in ultras

One of the main reasons for a DNF in an ultra is nausea and vomiting (23% of DNFs at the 2009 WSER were for this reason). Even among those that finished, up to 40% of the Western States field experienced nausea and or vomiting that affected race performance. Stomach problems can sabotage all the hard training you have done so it’s critical you have a strategy that works for you going into a big race.

Nutrition is a complicated topic but I’d like to break it down to 4 main questions:

  1. How much should I eat?
  2. What should I eat?
  3. When should I eat?
  4. What to do if something goes wrong?

How much should I eat?
This is governed not by how much energy you burn but by how much energy you can absorb. There is a big difference between the two and the gap comes from stored muscle glycogen and body fat.

Glace et al* estimated the energy cost of running 160km to be 13,560kcal in a 24 hour average finish time. Clearly, replacing that many calories would difficult enough sitting on the couch eating pizza all day, let alone trying to do it whilst running. The average participant in their study consumed 6047kcal or approximately 250 calories per hour. This creates a deficit of over 7000 calories, which must have derived from both stored muscle glycogen (around 1500-2000 calories), and the rest from body fat.

How many calories can we absorb?
This figure depends on the types of calories, but the general, recommendations are around 60g of glucose and 30g of fructose (fructose is absorbed in a different way to glucose). But given that so many people suffer stomach problems I recommend a strategy of eating the least amount possible in order to keep energy levels stable and get to the finish in the fastest time possible rather than eating the most possible. The less food we have to digest then the less chance of gastric upsets.

Consuming less fuel means you must be well adapted to tapping into existing fuel sources i.e. fat stores in the body. This does need to be practiced as fat oxidation is a different metabolic pathway.

Factors affecting absorption
The concentration of the carbohydrates in your stomach affect absorption. Simple carbohydrates are absorbed fastest in a 5-8 % solution, whereas complex carbs can be absorbed in concentrations as high as 15-18%.

What this means in practical terms is simple carbohydrates (e.g. glucose, sucrose) need more water to be absorbed than complex carbohydrates (eg maltodextrin). That’s why sports drinks containing simple sugars are always 6-8% in concentration. That’s not to say that one is better than the other. Two of the major sports nutrition products for ultras have opposite strategies. One uses simple carbs and the other complex carbs. Which one is best? That depends on the person.

Factors affecting calories needed
Body weight and exercise intensity are two major factors to consider here. The lighter you are, and the slower you go, the less you’ll need. Pace or intensity is definitely a huge determinant of calorie requirements because most people are able to rely on ‘fat burning’ when exercising at a lower heart rate. However, it is very important to note here that aerobic baseline can be improved. That is, we can work on fat oxidation at higher heart rates through training and nutrition strategies. This may be advantageous to those runners struggling to keep ‘down’ (i.e. not throw up) their race fuel during endurance events.

These two graphs illustrate two real life examples of how well two different athletes metabolise fat during exercise. You can see the second athlete will have to consume a far greater amount of carbohydrates to fuel his energy requirements compared to the first athlete.

good metabolism example

poor metabolism


How can you increase your fat burning ability?
Whilst this is worthy of another blog of its own – in simple terms its a matter of training your body to exercise without additional carbohydrates. Long runs performed with no breakfast and no additional carbohydrates is a great place to start. It is possible to run 4+ hours on nothing but water. BUT training for race nutrition is also necessary. I recommend building your long runs to 4 hours with no calories and then runs over 4 hours practise race nutrition.

Because of the difference in fat metabolism how much you need varies amongst individuals. Requirements will even vary throughout a race as the intensity varies i.e. many athletes will go faster in the first half of an ultra than the second so you will need to consume more fuel in the first half with a heavier reliance on stored body fat in the second.

Where to start ?
Experimenting in long training runs is the best way to learn what your energy requirements are and what carbs work best for you. Start with approx 30-40g of carbs per hour, erring on the side of less rather than more .

Why less rather than more?
If you haven’t got enough calories then you’ll start to feel hungry and/or a lack of energy. All you have to do to fix the problems is consume some calories.

If you have too many calories then you have to slow down to allow more blood to flow to the stomach, wait for the stomach and intestines to catch up and digest the food that’s there, so the muscles can get the calories they need. Adding more calories will just make the situation worse.

In addition, training with less as opposed to more will help build a strong aerobic baseline and assist the body to get used to tapping into stored fat as energy. Whereas if you constantly take on carbohydrate whilst training, you are going to need to constantly keep that up over many hours during race conditions.

So it’s a much quicker solution if you haven’t had enough calories than if you had too many.

What to eat?
The range of calories consumed in races is huge. From sports nutrition products like Tailwind, Hammer, V-Fuel, Powerboat, Endura, to real food like nuts, dried fruit, sandwiches, home made energy balls, cooked salted potato wedges, fruit, and then processed foods and drinks like lollies, chocolate, Coke, muesli bars, potato crisps etc. I have even heard of people have chicken drumsticks in an ultra.

The range is enormous and it means many people simply don’t know where to start. There are a few factors that will influence your choices.

Practical considerations
Can you transport it easily in your pack, can you unwrap it easily and will it survive extreme cold or heat? For example bananas might be your favourite food but try carrying a few in your pack for a few hours and see what state they are in. Chocolate bars may go down well but if your race is in the heat those chocolate bars may turn into an unpalatable mess.

If it doesn’t taste good then you will struggle to consume it in an ultra. The problem is that what tastes good 2 hours into an ultra may be unpalatable after 10 hours or more. In your longest training runs it may taste fine but if your race is twice as long as your longest training run then there is a good chance your taste buds may rebel later on in the race.

There is no way of knowing this until you have done a few ultras so its important to try a range of foods and develop a menu of what foods go down well so in a race, if option A is making you gag, then you have option B and C to fall back to.

A good strategy for many people is to mix up their food choices every hour so they don’t succumb to flavour fatigue. Whilst some athletes can take nothing but gels for a 100 mile race – others will feel nauseous after 3 hours of gels so trying other options is crucial.

Many find that even within the same brand of nutrition different flavours make a big difference. Most of the good brands use subtle flavours so they don’t over power you later in a race.

Given that most nutrition products are sweet, mixing it up with something salty can prolong how long you can tolerate the product for. So for example mixing up a sports drink with some slices of boiled salted potato every couple of hours may mean you can tolerate that product for the whole race.

As with training, practicing your nutrition is critical. You should never, ever try anything new on race day nor should you simply ‘go with the flow’ and do what your mates are doing simply because it works for them. It also pays to find out what food may be on hand at aid stations, supplied by the event organisers. As a general rule, you do not want to be relying on this because aid stations may run out of supplies quickly. But it’s still worth knowing what’s there as a fall back option.

Fibre, fat and protein
These will all slow down absorption – which may or may not be a bad thing depending on if you need quick energy or slow release energy. But be aware if you are having a low spot and you have a high fibre sandwich with butter and chicken in it, it is going to take a while for your body to process all that and get the glycogen it needs. If the next part of the course involves a steep hill then it’s maybe not a good idea!

We don’t need to add fat as we have plenty of fat to burn. Even a 55kg male with 5% body fat will have 2.75kg of fat on him which equates to 24,750 calories!

Protein is burnt to a small degree in ultra races and some will have you believe by consuming small amounts of protein you spare the body breaking down its own muscle tissue, others say it’s of no consequence.

As discussed above – different carbohydrates are absorbed at different rates depending on the concentration. You need to be aware of this and ensure you take sufficient water to enable optimal absorption. Pre made drinks are easy since you can mix them to the desired concentration but if you are having real food it gets a lot trickier.

For example if you consumed a handful of jelly babies/snakes or a few potato wedges – how much water will you need for them to be absorbed quickly?

Whilst it may be possible to calculate that on its own, when you factor in what is already in the stomach it’s basically impossible and comes down to trial and error in your training runs.

When should I eat?
Regularly and in small quantities is key. A large intake every two hours is going to be much harder to digest than a small amount every 20-30 minutes.

In a long race, this can be problematic because the mind and the body get tired. You need a strategy to ensure you don’t fall behind. For example, if you are planning on eating or drinking something every half hour then set a beeper on your watch or mark your water bottle to remind yourself to consume fuel. Sounds ridiculous, but after many hours on your feet, you will struggle to remember these details. And then the chances of something going wrong do increase.

What to do if something goes wrong?
Prevention is always better than the cure so again, practice makes perfect, but if things do go wrong then you only have a few options – choosing the right option is key.

Stomach fine – energy levels low
The simple solution is consume more calories. If you are feeling very low then something like Coke to pick you up fast may be needed but be aware there will be a crash in the near future if you don’t get some other calories in your system.

Energy levels low and stomach feels full
You need to decide whether to drink more water or not. Think back to how much food you have had and how much you have had to drink, if you have had more food than drink then by drinking more water you will decrease the concentration of carbs in the stomach making it easier for them to be absorbed.

Bloated and nauseous
Adding more to your stomach will probably make things worse.

You need to slow down and allow more blood to flow to the stomach to aid absorption. This may take hours and in the meantime you have very little calories to use.

One solution is a carbohydrate mouth rinse. It can trick the brain into thinking there is fuel in the muscles and give you enough energy to keep you going until your stomach can absorb what you have put in it. How long you can get by with just rinsing a carbohydrate solution in your mouth depends on lots of factors but probably not more than an hour or two depending on how fast you are running.

People have reported that ginger can help nausea in a race. Ginger tablets or ginger beer so that may be worth a try. Personally I have found Coke helps settle a dodgy stomach as it promotes burping but any gaseous drink would have the same effect I would imagine.

Flavour fatigue
If your taste buds are rebelling at the thought of consuming any more of your planned food then try something different – try some salted food (not because it has sodium – that’s a whole separate discussion – but because salty is the opposite of sweet).

Coping with the heat
Heat will effect the stomach since more blood is drawn to the skin to be cooled and therefore less blood available to the stomach. So pay attention to keeping the body cooled. This is more important than staying hydrated – if you keep the body cool then you don’t need to drink as much to begin with.

What do I do?
I am often asked this and whilst I recommend everyone find what works for them here is what works for me.

I use Hammer Perpetuem (I am not sponsored so I have no financial incentive for promoting their brand) and Hammer Gels.

I mix 9 scoops of Perp (strawberry flavour) with 3-4 banana flavour gels into a 600ml flask to make a thick paste. The gels provide some preservatives which means the Perp will last for hours longer.

One bottle will last me around 8-10 hours at the start of a 100miler and 10-12 hours at the end so I usually only need 2 bottles – sometimes 3 depending on the race.

Other than that the only other calories I’ll consume is Coke later in the race and the occasional gel when I am feeling a little flat.

In one race that I didn’t do so well at and my pace was a lot slower I found the vegetable soup at checkpoints went down amazingly well as did a cup of tea!

The key for you is to experiment in training and don’t leave getting your nutrition right until last. It is a critical component of racing and it can undo you on the day if it’s not practiced. In addition, do not believe everything you read. The theory and even the ‘science’ behind many commercial fueling options or suggestions may be great but if you cannot stomach it then it’s a total waste of money.

As I am not a qualified nutritionist this article was written with the help of Katie King – aka the Balanced Nutritionist. Katie is particularly interested in fat adaption for endurance athletes and she is passionate about reducing processed foods in the diet; her approach is as ‘whole’ and as ‘real’ as possible. She is Brisbane based but offers her services by Skype as well. You can find more about Katie and what she can help you with at www.thebalancenutritionist.com.au

* Glace et al, International Journal of Sports and Exercise Metabolism 2002,12,412-417; Food and Fluid Intake and Disturbances in Gastrointestinal and Mental Function During an Ultramarathon