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Nutrition for Runners
Long distance endurance events are performed at
moderate to high intensities. These energy demands
are met by the breakdown of carbohydrate and fat
sources in the body.
Internal carbohydrate stores in the body - mostly in the
form of muscle and liver glycogen, but these are limited
so if the muscles can be fed more carbohydrate,
athletes can perform better.
BUT - carbohydrate availability to the muscles is limited
by how fast it can pass through the intestine and into
the bloodstream - the transporters only work as fast it
takes to get you the sugar you need.
In the past it was believed that glucose was pretty
much the only type of carbohydrate that should be
ingested during endurance events and that the
maximum rate of glucose absorption in the gut was
1gram per minute. New research now shows that
fructose can also be ingested at the same time to
increase the total carbohydrate absorption. Studies
suggest that muscles can absorb a combination of
fructose and glucose almost 40% faster than glucose
alone. This combined consumption of glucose and fructose at
an approximate 2:1 ratio can increase the total
carbohydrate absorption and oxidation rate - resulting
in better performance.
Since this new research has come into light it has
shown that carbohydrate absorption can be increased
to at least 1.5g/min (possibly as high as 2.1g/min) to
increase the overall metabolic rate.
Researchers have determined that a 2:1 ratio of
carbohydrates, glucose:fructose may be optimal.
There are several sports nutrition products on the
market that have this ratio. Getting this ratio correct
can help your race performance.
What is the difference between glucose and
fructose and why these are important?
Both are classified as simple carbohydrates, but
glucose is the only one that your cells (including
muscle cells) use to produce energy directly.
For fructose to be used for energy, it must first be
absorbed in your gut, up-taken by your liver and then
converted into glucose. So by having a 2:1 balance of
both glucose and fructose in your race diet you can
get more overall carbohydrate into your muscle cells
for high energy production, and improved
performance.
Does my body weight matter in terms of intake of
fuel during a race?
No. It is the gut itself that is the limiter to how fast you
get carbohydrate into your bloodstream.
A 90 kg person doesn't have that much of a larger gut
than a 60 kg person, therefore it doesn't make sense
to overload the 90 kg person with more carbohydrate. The recommendation remains the same for everyone,
irrespective of their body weight.
How to calculate:
Optimum: 1.5g carbohydrate per minute of exercise
High Five energy gel = 23g of carbohydrate
Exercise time: 1hr 40mins (100mins)
100mins
23(g) x 1.5(g) = 6 gels This is optimum intake.
Nutrition for Runners
What about fluids?
Should I use caffeine?
You’ll notice that we are not giving you a dedicated
fluid intake recommendation. This is because we now
know that fluids should be consumed, not at a set
rate, but in accordance with your own body’s needs.
Caffeine has both positive and negative effects on the
body. It acts as a central nervous system stimulant
which causes changes in muscle contraction and has
effects on cardiac muscles. Caffeine may also help
with carbohydrate absorption and oxidation however
the performance improvement often shown with
caffeine use is probably related to a decreased
perception of fatigue as well as its direct effect on
muscle (ie a placebo effect).
The key is for fluids to be available during the race and
for you to be able to drink according to your thirst.
Your body’s own inbuilt thirst centre is the best gauge
of your own body’s fluid needs, just listen to it’s
advice ;o)
You’ll also note that there is no recommendation for
electrolyte consumption, that is because recent studies
have shown there is no influence of low versus high
sodium (salt) on glucose absorption and no effect of
sodium supplementation in the prevention of cramping.
The only principle you need to follow is to ensure there
is some level of sodium in your diet during the day.
By consuming a normal endurance race diet (i.e. gels)
there will be enough sodium for your body.
Everyone has different responses to caffeine; some
athletes will experience a positive effect while others
may have no effect or negative effects from the same
dose. Trialling caffeine in different doses is the best way
to find out if it works for you and at what level of intake.
We recommend that you start with a caffeine dose of
3mg/kg as this does typically work well for most
athletes. You should consume this amount
approximately 45mins prior to race start.
Nutrition for Runners
How does your body get energy?
The carbohydrate in food and drink is what
fuels your body.
It it transformed into blood sugar or blood
glucose (BG).
BG is essential to DRIVE the body’s power and
endurance metabolic systems.
BG is essential to keeping the whole system
firing.
If BG levels drop, the system cannot function
efficiently and the body cannot perform at it’s
best.
For strength and power sports, the fuel of
choice for muscles is carbohydrate, even more
so than for endurance sports. So it is very
important to have this readily available to
facilitate training. Forget about low-carb diets!
Protein functions in a structural (repair) and
transport capacity (facilitates transport of sugar
back into cells for recovery) and is therefore an
important part of the nutritional equation also.
However, too much protein is hard on your
kidneys.
Maintaining energy by
understanding Glycaemic Index (GI)
GI is the measure of how long carbohydrate
takes to turn to blood sugar (BG)
Low GI foods, like pasta, rice and whole grains
take a longer time to turn to BG and therefore
provide sustained energy.
High GI foods, like sports drinks, glucose and
processed grains, alongside a source of protein
are good foods to have after training to
maximise recovery.
High GI foods work by stimulating blood
glucose and an insulin response to help prevent
muscle degradation.
This optimises uptake and replacement of
glycogen, or stored glucose, and prepares the
body for subsequent training sessions.
Index of Low GI Foods:
http://www.the-gi-diet.org/lowgifoods/
What to do when you are exercising
Pre-exercise fuelling
1-2 hours before a workout have a low GI
carbohydrate snack.
Aim for around 50-100 grams of carbohydrate
depending on your energy needs.
Drink your caffeine drink 3mg/kg 45mins before
the start.
During Exercise
1.5g/min of glucose and fructose in an
approximate 2:1 ratio.
Fluid needs: Remember thirst is your gauge.
Start your session by being “topped up” with
water then replenish throughout the race.
After exercise WITHIN 30 mins.
1.2g carbohydrate/kg + 10-20g protein within
30mins after training.
Choose high GI sources of carbohydrate to
speed uptake of glucose into cells.
Repeat every hour for 3 hours after, or a pasta/
rice based meal with a source of protein,
whichever is more practical.
The greater the intensity and duration of the
workout, the more important it is to follow this
protocol closely.
If the workout was light and easy then you
won’t need as much food as suggested.
Example:
Protein smoothie with banana, honey, low fat
yoghurt. (80g carb, 28g protein)
Don’t forget to re-hydrate.
Carbo Loading
Tips for the Carbo loading
Start 1 1/2 days before race day.
Have high carbohydrate meals with low GI.
Your reduction in exercise will help your carbo
loading.
Eat foods that you know won’t make you sick.
On race morning have a low GI breakfast 1-2
hours before the race.
Some food facts:
Benefits of healthy eating:
Obtain energy for fuelling the body.
Obtain essential nutrients needed for the body’s
functions.
Maintain a healthy weight and feeling of wellbeing.
Prevent nutrition-related diseases (obesity,
diabetes, cancer, heart disease).
Healthy immune system.
Live longer ;o)
Energy you need
Carbohydrate = 50-60% of total energy.
Fat = 25-30% of total energy.
Protein = 10-15% of total energy.
There are 2 types of Carbohydrates; Complex (starches) and Simple (natural and
refined sugars).
Natural sugars, such as fruit, vegetables, milk
and yoghurt are low GI and high fibre (dairy
foods do not have fibre).
Low GI foods take a longer time to turn to
blood sugar so they are good for providing
sustained energy and keep hunger levels at
bay.
Wholesome grains such as rolled oats,
multigrain bread, muesli and beans/pulses are
also low GI and high fibre.
Refined sugars should be limited but are ok in
small amounts and in moderation.
Nutrition labels give a breakdown of total
carbohydrates and sugars which can be
confusing if the sugars are natural.
It is more important to evaluate the GI than the
sugar content.
Protein and Fat
Eating 2-3 small servings of lean meat or meat
alternatives each day will provide the body’s
protein requirement.
Protein is also found in whole grains, dairy
products, nuts, seeds, vegetables and soy
foods.
A low-fat diet is important to keep cholesterol
levels down.
Heart healthy fats, such as olive oil, seed oils,
avocado, fish fat, nuts, seeds, dark chocolate
and coconut are excellent for cardiovascular
health and should be consumed in small
amounts too.