Fuel for Racing and Training
As a dietitian and a runner I am all about
optimising performance or training outcomes through fuel so I thought I’d share
If you’re an experienced runner you will know
how much more enjoyable a run is when you’re well fueled and properly
hydrated. Getting your fuel right for your training runs might be the
difference between your run being hard work and your run being really, really
hard work which may of course influence how far and how fast you run in
training. More importantly, if you’re running competitively, getting your race
day fuel right can really improve your performance.
There are a lot of people sharing their opinion
on the Internet, people who have written books and people trying to sell
products that will try to convince you that their way is the right way but here
I have summarised the best available scientific evidence on the optimum way to
fuel yourself for performance and remember: nutrition is science, not opinion.
Fuel: The Basics
When we talk about fuel for exercise we are
basically taking about carbohydrates.
The basic function of carbs in our body is to
provide energy. I think we trap on about energy quite a bit but it is worth
thinking about energy in our bodies in a more abstract way to help to
Just like all our electronic goods need energy
in the form of electricity, our bodies need energy to function. Some electrical
items like hairdryers, need a lot of electricity to function for short periods
and some, like fridges need a small amount of constant energy. Our bodies are
the same, our lungs, livers and other organs need a little bit of constant
energy and when we exercise, our muscles, heart and lungs need a lot of energy.
The energy that our body uses is glucose which
we get from carbohydrates in our food.
Carbs come in many different forms, from the
complex starches like bread and potatoes, to the moderately complex like milk
sugar, to the simplest forms like table sugar and syrup.
When we eat any form of carbohydrate our body
gets to work to break it down to glucose.
As discussed, we need constant energy just for
our lungs and our brains to function and for that reason, you use significantly
more energy during a 6 hour nights sleep than you do during a 1 hour run. So in
order for our bodies to continue to work at all times we have three ways of
making sure glucose is always available.
The easiest way for our bodies to have glucose
is when it is still in our bloodstream after a meal. In electrical terms, this
is a relatively small supply that is sitting in the wires (i don’t know if that
is possible electronically…but you get the idea).
When we eat more carbohydrate than we need at a
meal (intentionally to fuel up or unintentionally because we’re greedy!) and we
have more glucose than we immediately need, we store it in our muscles and
livers as glycogen so that it is available later. Glycogen is a bit like a battery.
Stored energy that will eventually run out. This is so important for endurance
exercise because optimising glycogen stores allows us to keep up our pace when
the glucose from the last meal has been used up – which is pretty quickly.
As a last resort, if all of the glucose in the
blood stream is used up and the stored energy in the batteries in your liver
and muscles is used up, we turn to our biggest source of energy – body fat.
This is when athletes talk about ‘hitting the wall’ because fat has to be
converted to glucose via quite a complex process so it delivers energy quite
slowly and when you’re relying on it to fuel challenging exercise it doesn’t
get to your muscles quickly enough which causes fatigue.
That said, if you’re trying to get your body fat
percentage down, this is why fasted cardio is so challenging but so effective
because you are forcing your body to use your fat stores rather than relying on
glycogen. But that’s a story for another day.
So it’s the day before the big race and you want
to optimise your performance. Clearly, it would be ideal if your diet had been
perfectly balanced and meeting all your nutritional needs for the preceding
months and years but for the purposes of this article we’ll focus on the last
few days pre-race.
At this point, we want to concentrate on making
sure that your batteries are fully charged (meaning your glycogen stores are
replete) and that you have a plan to make sure that you’ve got some glucose in
your blood stream at the start of the race.
So, for events that last 60-90 minutes, make
sure you rest for 24 hours before and the day before and consume 7-10grams
of carbohydrate per kilogram of body weight.
To give you an idea, a slice of bread is about
10g of carbohydrate, a large bowl of cereal is about 40g and 150g cooked pasta
is 50g of carbohydrate so this is quite achievable.
If you’re running a full marathon or
more, you will need to taper you’re exercise for a week leading up to the event
and aim for 8-10g of carbohydrate per kilogram of body weight per day for
2-3 days before the event. Fortunately the days of heavy carb loading
regimens are over!
On race day in an
ideal world you would have a carbohydrate rich meal of around 3g of
carbohydrates per kilogram of body weight 3-4 hours before the event.
Usually though, events are in the morning and getting up at 4am to eat pasta
isn’t usually all that appealing so if you prefer to sleep then just make sure
you’ve had a carb heavy meal the night before.
It is also important that you include your
fuelling plans in your training at least twice because you don’t want to be
surprised on race day by that that 4am bowl of pasta may have unwanted
digestive effects at a suboptimal time!
For most people, avoiding a heavy meal 2-4 hours
before racing is important but it is useful to have a high a high
carbohydrate snack 30-60 minutes before racing if you can tolerate it.
We’re looking for 50g of quite refined carbohydrate at this point so a
slice of toast or a couple of slices of malt loaf or yogurt and honey with a
glass of orange juice would be ideal. This will provide you with that extra
boost for the start of the race.
Another thing that has been shown to improve performance
is caffeine. Between 3-6mg of caffeine (equivalent to about 2 cups of coffee
depending on your weight) 40 minutes before races and training can be really
effective. Increasing this dose doesn’t make any difference so please don’t
start taking a fist full of caffeine tablets on the start line and make sure
you trial using caffeine in your training before race day. If you’re not used
to having caffeine or you know that you are particularly sensitive to it, don’t
use it for this purpose.
During long distance races, performance can be
improved by consuming 30-60g of rapidly absorbed carbohydrate per hour.
Good examples would be a bottle of sports drink or jelly babies which
conveniently contain 5g carbs per sweet so it’s easy to make sure you’ve had
the right amount!
The rest is down to sheer determination and good