Running Nutrition
Fuel Utilization
During endurance activity the body uses muscle glycogen, blood glucose, muscle triglycerides, and free fatty
acids from fat tissue to provide the fuel to perform. As exercise intensity increases during an endurance bout,
more carbohydrates are used. However, since carbohydrates are limited in supply, as the exercise continues
(and the body's carbohydrate stores diminish) more stored fats are used. Unfortunately the metabolism of fat is
less metabolically efficient; therefore when carbohydrates become limited, exercise intensity must diminish.
Since the body typically contains enough stored fat to fuel several marathons, the focus of eating for endurance
activity should be on the carbohydrate content of the diet.
Before The Event
Eating a relatively calorie dense meal 2-4 hours before a race or several smaller meals between 2-5 hours before
a race is absolutely essential. By eating this meal, the activity will be fueled by the nutrients provided during the
meal. This can end up delaying fatigue and improving performance.
While it is important not to wait too long between meals before an event, it is equally important not to eat too
close to the event. Eating a meal within 1.5-0.5 hours before a race can lead to gastrointestinal distress. You
will simply feel too full or even sick as a result of eating too close to the event. It can also cause early fatigue.
Here is an example of what the pre-race meal should contain:




Adequate water (1 liter)
4-5 grams of carbohydrate (300 grams for a 70 kilograms individual)
A small amount of protein (20-40 grams)
A small amount of fat (10-20 grams)
During The Event
Although eating as directed above will allow you to top off glycogen stores coming into the event, you are not in
the clear yet. You still have to contend with two potential enemies: 1) dehydration and 2) rapid glycogen
utilization and depletion. Let's start with the glycogen situation.
While it is very important to start a race with muscle glycogen stores topped off, it is also
important to note that the body tends to use carbohydrates much more quickly when there are
more available. Unfortunately, even if you are topped off, muscle glycogen depletion can still
occur. In order to prevent this from happening you should be consuming sports drinks or gels
during your entire race. Since the body can only use about 60 grams of carbohydrate per hour
during exercise, one to two servings of a drink like Gatorade or Powerade (or 1-2 servings of
sports gels) per hour should do the trick for carbohydrate supplementation.
While the above recommendations take only carbohydrate needs into account, we should
now consider fluid needs. During hot and humid days, the body can lose up to 2-3 liters of
water per hour. This water loss corresponds to an unacceptable 4-6 pounds of weight loss
per hour. This loss of water is detrimental to performance as a weight loss as small as 1-2%
of body mass (1.5-3.0 pounds for a 150 pounds runner) can lead to impaired blood volume,
stroke volume, cardiac output and oxygen consumption. Therefore it is very important to
keep fluid intake quite high during exercise. To this end, you should focus on consuming 2
liters of water per hour to prevent dehydration.
Here are a few examples of how to hydrate and feed the body during competition:


Drink 2 liters of water per hour while consuming 2 servings of a sports gel-type product; or
Dilute 2 servings of a powdered Gatorade or Powerade-like product in 2 liters of water
After The Event
Once you have crossed the finish line, the nutrient battle is not over; you
have one more responsibility to your body. Endurance exercise, much like
strength exercise, causes depletion and damage of skeletal muscle.
Therefore after such exercise, it is important to begin repletion and repair
immediately after the race. To summarize these recommendations,
however, since the post exercise period is the optimal time to replenish and
repair damaged muscles, this is the time to consume easily digestible liquid
carbohydrates and protein.
Your post exercise strategy should contain:


0.8g/kg carbohydrate (56 grams carbohydrate for a 70 kilograms runner)
0.4g/kg protein (28 grams protein for a 70 kilograms runner)
Some examples of what to drink/eat during this time are as follows:


A specifically formulated recovery drink such as Biotest Surge: 305 calories, 25 grams protein, 50 grams
carbohydrate, 0.5 grams fat
A homemade recovery drink containing 1 serving whey protein and 2 servings Gatorade: 369 calories, 25
grams protein, 66 grams carbohydrate, 0.5 grams fat
Then, every two hours after this for the remainder of the day, be sure to consume a meal containing protein and
carbohydrate.
Why Carbohydrate Load?
Intense endurance exercise performance is often fueled by a combination of stored carbohydrate (glycogen in
the liver and the muscle) and stored fat (triglycerides in the muscle and adipose tissue). While fat burning can
contribute significantly to an endurance athlete's fuel needs, there are a few reasons why it is not the best
source of energy during intense activity.
1. The rate of fat metabolism is slow compared to the rate of carbohydrate metabolism. Therefore, during
intense exercise, when the body demands the quick provision of energy, fat metabolism cannot provide
energy quickly enough and the body must slow down.
2. Metabolizing fat is more oxygen costly than metabolizing carbohydrate; making fat metabolism more
inefficient than carbohydrate metabolism.
So, it should be clear that without adequate carbohydrates in
the body, the endurance athlete will suffer at the hands of
the infamous "bonk". You see, since body's carbohydrate
stores are limited (a 70 kilograms individual may store about
400 total grams of carbohydrate), endurance events lasting
greater than 90 minutes may deplete muscle glycogen to low
levels, leading to early fatigue (and thus being passed by
someone's grandmother).
Since the carbohydrates in the body are consumed
preferentially to fats, are used rapidly during intense exercise
it is clear that any attempt to increase the body's
carbohydrate stores during longer duration events may help with performance. One such attempt to try to
boost the body's glycogen stores is the pre-race carbohydrate loading scheme. By following a carbohydrate
loading protocol as such, carbohydrate stores can increase significantly (in some cases, muscle glycogen has
doubled) and this may provide greater fuel for the latter portions of the race. So, if you are about to compete in
long duration endurance events, you owe it to yourself to give carbohydrate loading a chance.
How Do I Carbohydrate Load
Over the years there have been several carbohydrate loading schemes proposed. Original schemes were based
on the fact that following a 3-day, ridiculously low carbohydrate diet (less than 50 grams) causes an increase in
muscle glycogen storing enzymes.
Therefore, starting 6 days from your event, "depleting" muscle glycogen with this 3-day low carb diet (exercising
intensely on all three days as well), you can set your body up for a "rebound" of carbohydrate storage during the
three days immediately prior to the event. For those next three days, you simply rest, eat a very high carb diet
(10 grams of carbohydrate per kilogram of bodyweight), and watch your muscles swell up with energy.
One problem, though, with these original schemes is that they were very difficult to follow for athletes
accustomed to regularly eating carbohydrates. In addition, the three days of carbohydrate depletion led to such
low energy levels during these three training days that performance suffered on these days. Although
performance would ultimately "rebound" along with the glycogen stores, this phenomenon wreaked havoc on
the athlete, causing psychological distress. Think about it. The last three practices before race day were their
worst performances! So other schemes were devised.
Here is a more modern scheme for carbohydrate loading that is nearly as effective as the one discussed above, but much
more manageable:

Day 6 - Training Day - Low carbohydrate diet (<200g carbohydrate)*

Day 5 - Training Day - Low carbohydrate diet (<200g carbohydrate)*

Day 4 - Training Day - Low carbohydrate diet (<200g carbohydrate)*

Day 3 - Recovery Day - High carbohydrate diet (>10g/kg carbohydrate)**

Day 2 - Recovery Day - High carbohydrate diet (>10g/kg carbohydrate)**

Day 1 - Recovery Day - High carbohydrate diet (>10g/kg carbohydrate)**

Event Day
(*) During the low carbohydrate days, you must increase your consumption of good fats (Omega 3 fatty acids and
monounsaturated) as well as complete protein sources in order to keep your energy intake the same. Therefore
carbohydrate will make up only a small percentage of your daily intake.
(**) During the high carbohydrate days, decrease your fat and protein consumption as your diet should be >80%
carbohydrate.