Race Nutrition
I should really let on my own pre race diet but it just is not good enough. Hence the following article is reprinted in order to sink some good eating habits in for the furure!
March 18, 2011 by Bill Henderson, MD
Exercise physiologist Dr.
William Henderson of Endurance Science. In the following article, he explains an approach to race nutrition using his 2009 Marathon des Sables as an example.]
The strategies
are applicable in large degree to other races and types of events. As
always, try nothing new on race day(s).
Pre-Race Nutrition
There is a great deal written about pre-race carbohydrate loading
strategies. I think that the evidence supporting these is reasonable,
but the reality of complex loading strategies is complicated by athlete
motivation and the demands of travel and timing specifically related
to the MdS. Traditional carbohydrate loading strategies usually involve
one or more runs associated with carbohydrate restriction for several
days (i.e., 2-4 days) prior to the big event. The purpose of these days
is to thoroughly deplete liver and muscle glycogen stores. This
depletion stimulates the activity of glycogen synthetase – the enzyme
largely responsible for causing glycogen production and storage –
beyond it’s normal levels activity. The athlete then eats large doses
of carbohydrate, in an effort to saturate the body’s glycogen storage.
It is theoretically possible to store enough glycogen this way to last a
full marathon distance.
I think that this specific type of protocol is not needed for MdS
nor for many other ultra-distance races. There are three reasons I
would not recommend aggressive depletion-loading techniques
Firstly, here are several risks. Specifically, running several long
runs prior to the start day means running whilst tired from travel,
which increases the risk of injury and illness. I would worry that this
places too much physiologic strain on an athlete. It is my impression
that fewer and fewer top athletes and coaches are using these
strategies anymore because of the psychological and physical effects.
Secondly, the benefits of aggressive loading strategies diminish
when the athlete is able to maintain blood glucose levels during
running by eating. It is far more important to maintain adequate
carbohydrate intake whilst running than to focus on difficult pre-race
loading strategies. Given the multi-day nature of MdS, the small
positive benefit in terms of liver and muscle glycogen density on day 1
is minimal.
Thirdly, you will naturally undergo carbohydrate loading and
glycogen storage during the week prior to the MdS or other races as you
taper your mileage. It is not necessary to eat massive amounts of
carbs in the days prior to the race start. If you eat your normal
amount of calories (possibly focused slightly more on carbs than usual)
whilst dropping your training mileage, you will naturally store
glycogen and fat.
Besides carbohydrates, it is useful to think about “topping off”
your electrolyte and water stores, too. Travel to the competition, dry
environments, and stress will all alter your water and sodium balance.
Careful attention to hydration and a modest increase in sodium intake
for 3 days prior to the race start will be of benefit.
In the case of MdS, all of these strategies will cause you to be
0.5-2 kg heavier at the start line than your usual race weight. That’s
not a bad thing – think of the weight as fuel.
Race-Morning Nutrition
Overnight, your liver glycogen stores can deplete by as much as 50g
(of 100g total). Your muscle glycogen stores (400g) are unaffected. One
of the main purposes of the pre-race meal is to top off your liver
glycogen stores. As it takes a while to fully digest your breakfast and
form glycogen, this meal should happen about 2-3 hours pre-race start.
Again, a relatively high carbohydrate percentage is called for (80% or
more).
There are some additional theoretical reasons why eating your
pre-race meal within 2-3 hours may impair performance, particularly if
your meal is composed mostly of simple rather than complex
carbohydrates. It is possible that after the meal you will secrete a
lot of insulin. This may lead to the inhibition of lipid mobilization
(fat burning) during aerobic exercise, which means reduced fats-to-fuels
conversion, and thus potentially less available energy. Additionally,
high insulin levels may enhance muscle glycogen depletion during
exertion.
If you finish your pre-race meal about three hours prior to start
time, your insulin and blood glucose levels will have to normalize,
thereby avoiding these problems. After three hours, hormonal balance
is restored, and you won’t be at risk for increased glycogen depletion.
Eating within three hours of a race promotes faster release/depletion
of both liver and muscle glycogen and inhibits fat utilization. The
combination of accelerated glycogen depletion and disruption of your
primary long-distance fuel availability may impair your performance.
Summary: Eat a meal rich in complex carbohydrates 3-4 hours prior to start time
- Costill DL, Hargreaves M. Carbohydrate nutrition and fatigue. 1992, Sports Med., pp. Feb;13(2):86-92.
- Costill, DL. Carbohydrates for exercise. Dietary demand for optimal performance. 1988, Int J Sports, pp. 9:1-18.
- Hargreaves, M. Pre-exercise nutritional strategies: effects on
metabolism and performance. 2001, Can J Appl Physiol., pp. 26
Suppl:S64-70.
- Hawley JA, Dennis SC, Noakes TD. xOidation of carbohydrate ingested
during prolonged endurance exercise. 1992 , Sports Med. , pp.
Jul;14(1):27-42.
- Wee SL, Williams C, Tsintzas K, Boobis L.Ingestion of a
high-glycemic index meal increases muscle glycogen storage at rest but
augments its utilization during subsequent exercise. 2005 , J Appl
Physiol., pp. Aug;99(2):707-14.
- Coyle EF, Coggan AR. Effectiveness of carbohydrate feeding in
delaying fatigue during prolonged exercise. 1984, Sports Med., pp.
Nov-Dec;1(6):446-58.
- Dennis SC, Noakes TD, Hawley JA. Nutritional strategies to minimize
fatigue during prolonged exercise: fluid, electrolyte and energy
replacement. 1997 Jun, J Sports Sci., pp. 15(3):305-13.
In-Race Nutrition
Carbohydrate is the best fuel for your body during intense exercise.
Endurance athletes can only store about 400g of muscle carbohydrate
(as glycogen) and around 100g of liver glycogen. This amounts to not
much more than 2,000 kCals (500g x 4 kCal/g) in total – enough for
about 15 miles of fast pace running for a 165 pound athlete.
Happily, well-trained endurance athletes can supply some of their
energy needs from fat, even at moderately high intensity levels.
Although fat and protein can both serve as fuel sources, carbohydrate
is still essential for high intensity performance. There are several
reasons why carbohydrate is an important fuel, but one of the most
important is that only carbohydrate can supply energy rapidly enough to
generate ATP (the energy releasing molecule used to drive muscular
contraction) during vigorous exercise. Furthermore, even when exercise
intensity is lower, and more of the energy can be derived from fat, a
continual breakdown of carbohydrate is required to allow the efficient
oxidation of fat for energy.
So how much carbohydrate should be eaten during running? The answer
is essentially “as much as possible.” For example, assuming an athlete
runs 6 miles/hr (very fast over this terrain – less than 5% of
competitors can achieve this!) during the MdS, and given the difficulty
of the terrain (30-50% more energy needed per miles run than normal
trail or road) a 165 pound athlete will burn approximately 1,000
calories per hour. Most athletes of this size can only ingest around
250-300 cal/hr. So no matter how much you eat, you will still be
“running a deficit.” Your goal should be to eat as much as feasible
without causing nausea. This is typically around 250 calories per hour.
Many people feel that a bit of protein makes them feel better during
long efforts. If this is true for you, then use a food plan that has
some protein in it. I would not recommend foods with significant fat
in them if your effort is going to be intense. Ingested fat slows down
the emptying of food from your stomach (potentially leading to nausea),
and is not readily available as an energy source during exertion. Some
people deliberately include fat in their intra-race food for very long
events – specifically because it improves taste/palatability and the
sense of “fullness.” These seem like good reasons to me – but don’t do
it simply to “get more calories,” it doesn’t work that way…
Summary: 250 kCal an hour (if you can) from the first to the last step of the race. Focus on carbohydrates!
Carbohydrate Choices
Eating large amounts of two different carbohydrates during prolonged
exercise allows greater conversion of carbohydrate to energy than
ingesting one alone. Combining maltodextrin with fructose can
elicit higher carbohydrate oxidation rates during exercise than
maltodextrin alone because they use different intestinal carbohydrate
transporters. This means that more carbohydrate can be absorbed from
your intestinal tract more quickly, potentially decreasing fatigue and
improving performance…Peak conversion of ingested carbohydrate to
energy measured during the last 30 minutes of exercise was about 40%
higher when athletes used a combination of fructose and
maltodextrin (1.5g/min) versus maltodextrin alone (1.06g/min). There
are a vast number of powders and gels available. You may wish to
experiment with ones that contain a mix of fructose and maltodextrin as
fructose can cause discomfort and diarrhea in some athletes.
Recovery Nutrition
At the end of each day’s effort at the Marathon des Sables, you will
probably want to hang out with other runners, relax or just sit and
wish you had never signed up for such a ridiculous race. There or after
any other long race, you may not be thinking much about eating,
particularly if you are hot or feeling nauseous. However, it is
essential that you work on early restoration of your glycogen stores. A
classic exercise science study showed that a typical diet (with about
45% of calories derived from carbohydrate) produced a steady depletion
in muscle glycogen during three successive days of running training (10
miles per day).
However, when runners were given additional dietary carbohydrate,
they achieved near maximal repletion of muscle glycogen within 24
hours. We know that the timing of this carbohydrate reloading is key.
The highest muscle glycogen synthesis rates occur when large amounts
of carbohydrate (1-1.85g per kg of body weight per hour) are consumed
immediately after exercise and at 15- to 60-minute intervals
thereafter, for up to five hours.
It seems possible that combining protein with carbohydrate in the two
hours after exercise can nearly double insulin release, which results
in more stored glycogen (insulin is a powerful hormone that is
centrally involved in the management of glucose levels and in
carbohydrate/glycogen storage). The optimal carbohydrate to protein
ratio for this effect is 4:1 (four grams of carbohydrate for every one
gram of protein). One study found that athletes who refueled with
carbohydrate and protein had 100 percent greater muscle glycogen stores
than those who only ate carbohydrate. Consider adding protein or amino
acids to your post effort meal (0.4g of protein per kg of body weight).
Summary: Eat 1-2 g/kg carbohydrate within 30-60 min of
exercise. Repeat this every hour. Consider adding 0.4g/kg protein to
this to increase glycogen re-synthesis and muscle recovery.
- Williams MB, et al. Effects of recovery beverages on glycogen
restoration and endurance exercise performance. Betts JA, et al. 2003
Feb;, J Strength Cond Res. , p. 17(1):.
- Ivy JL, Goforth HW Jr, Damon BM, McCauley TR, Parsons EC, Price TB.
Early postexercise muscle glycogen recovery is enhanced with a
carbohydrate-protein supplement. 2002, J Appl Physiol., pp.
Oct;93(4):1337-44.
- Zawadzki KM, Yaspelkis BB 3rd, Ivy JL. Carbohydrate-protein complex
increases the rate of muscle glycogen storage after exercise. 1992 , J
Appl Physiol. , pp. May;72(5):1854-9.
- Levenhagen DK, Carr C, Carlson MG, Maron DJ, Borel MJ, Flakoll PJ.
Post exercise protein intake enhances whole-body and leg protein
accretion in human. 2002, Medicine and Science in Sports & Exercise,
pp. May; 34(5): 828-37.
- Miller SL, Tipton KD, Chinkes DL, Wolf SE, Wolfe RR. Independent and
combined effects of amino acids and glucose after resistance
exercise. 2003, Medicine & Science in Sports & Exercise, pp.
March; 35(3):449-55.
