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Top Three Dietary Performance
Inhibitors for Runners
The end of this article talks promotes
using the glycemic index and many of you know I'm not a huge
fan of it (see nutrition tip a few months back). When foods
are combined (protein, carb and fat) the index doesn't work,
(visualize mixing different paint colors together...you end
up with a different color..or different index) BUT when carbs
are eaten separately as in a situation where a runner is stockpiling
carbs for training, then it makes more sense. I can not tell
you how often I see people unintentionally undereating and not
getting the progress they want. This article supports my findings
too.
By Kim Mueller, M.S., R.D.
For Active.com
April 21, 2006
It's well known that nutrition plays
a key role in developing and maintaining of top athletic form
and overall sports performance. Even so, many athletes solely
concentrate on training, neglecting their nutritional program
and depriving themselves of true peak performance.
Proper nutrition helps an athlete produce
and utilize energy more efficiently. Furthermore, a sound nutrition
program will help prevent nagging injuries that can interfere
with training.
Recently, I completed full nutritional
analyses on a group of 25 competitive athletes, including elite-level
distance runners (12 males, 13 females), to see what nutritional
deficiencies existed. The purpose of this research project was
to determine the overall metabolic efficiency and adequacy of
a runner's diet in relation to the high demands of the sport
and the recommendations specified by National Research Council.
The following three surprising discoveries
were made:
1. The runners weren't eating enough.
Runners, especially those training
for the marathon and beyond, expend extraordinary amounts
of energy -- in some cases over 4,500 calories a day. In fact,
the energy needs per pound of body weight are amongst the
highest of any endurance sport; it's estimated that runners
require 16-30 calories per pound of body weight, an amount
dependent on time spent running per day.
The calculated needs for the runners
in this study were 21 calories per pound of body weight based
on the mean calculated daily energy expenditure of 3,105 calories
(see below). In contrast, the average energy intake of these
runners was only 2,392 calories, over 700 calories short!
Energy
intake vs. energy expenditure in runners |
|
Gender |
Calorie
intake |
Calorie
expenditure |
Female |
2,007 |
2,794 |
Male |
2,810 |
3,441 |
|
While a 700-calorie imbalance is suggestive
of a 1- to 1.5-pound loss per week, very few of the runners
were actually losing weight. Why? The human body has an ability
to adapt to a lower level of energy intake, allowing for preservation
of weight despite a calorie shortage. Unfortunately, this
means the body is less efficient at using the calories and
nutrients consumed during training. A lack of calories also
depresses immune function, making the athlete more vulnerable
to illness and injury during intensive training.
So, it's feasible to conclude that
these runners would perform at higher levels if they consumed
an additional 700 calories. For those runners who want to
lose weight during training, a calorie deficit of 250-500
calories a day is more appropriate.
Solution: Based on approximately
an hour of running a day, runners should consume 21 calories
per pound of body weight each day.
2. The runners weren't consuming enough
carbohydrates
There's a plethora of sound research showing the profound
performance benefits associated with high carbohydrate intake,
including optimal mental functioning, muscle glycogen saturation,
enhanced fat burning, protection against protein/muscle breakdown
and improved immune function, so it was surprising to find
these runners were only consuming 69 percent of their daily
carbohydrate needs (see below).
Mean
carbohydrate intake vs. mean carbohydrate goal in
runners |
|
Gender |
Carb
intake |
Carb
goal* |
Female |
250
grams |
419
grams |
Male |
396
grams |
512
grams |
|
|
*Carbs
goal intake was based on 60% of total goal calorie
amount as determined by physical activity diary |
A significant carbohydrate
deficiency like this can negatively affect performance because
the athlete is more vulnerable to liver and muscle glycogen
depletion, increasing risk for the mental "bonk"
and performance-declining "wall."
For optimal performance, athletes should
try to consume 3 to 5 grams of carbohydrate per pound of body
weight; the runners in this study had a calculated carbohydrate
need of 3.2 grams per pound body weight.
At meals, try to fill three-quarters
of every plate with carbohydrate-rich foods like fruits, starchy
vegetables and whole grains; fill the remaining quarter with
protein-rich foods like meat, poultry, fish, nuts and dairy
products.
Solution: Based on approximately
an hour of running a day, runners should consume 3.2 grams
of carbohydrate per pound of body weight.
3. The runners were following erratic
eating patterns
A consistent, balanced intake of nutrients
throughout the day will improve metabolic efficiency necessary
for peak performance. Breakfast is the most important meal
of the day because it kick starts your metabolism, allowing
the body to utilize fuel more efficiently. Eating every two
to four hours after breakfast keeps the engine running at
high levels throughout the day.
Sixteen percent (four) of the runners
in this study skipped breakfast, with only 20 percent (five)
actually eating in two- to four-hour increments. Furthermore,
the majority of runners weren't balancing out their plate
properly, ultimately leading to waning energy levels during
the day.
So which foods should you choose for
meals and snacks? There's a term in the field of sports nutrition
that all runners should become familiar with: glycemic index.
Glycemic index refers to how quickly foods enter and leave
the bloodstream. High-glycemic foods enter the bloodstream
rapidly, giving a quick energy boost, but they also leave
the bloodstream rapidly, causing reduced energy levels and
increased cravings.
In order to prevent the quick drop
in energy levels, consume high-glycemic foods with protein.
For example, have rice -- a high glycemic food -- with beans
-- a protein-rich food with a low-glycemic value. Another
example: Mix a banana into yogurt.
Moderate-to-low glycemic index foods
should be consumed on a more consistent basis due to their
ability to sustain energy levels and overall metabolic efficiency
for longer periods of times. See below for a listing of glycemic
indices for common foods, or visit http://www.glycemicindex.com/
for more information.
| Glycemic
Index of Common Foods |
| |
|
|
| High |
Medium |
Low |
| Beets |
Bananas
(unripe) |
Beans,
peas |
| Bread:
white, wheat; bagels |
Bran/blueberry
muffin |
Barley
(pearled), bulgar |
| Candy
bars (most), jelly beans |
Bread:
100% whole wheat, pita, pumpernickel, sourdough |
Cereal:
All-Bran |
| Cereals
- most; corn/rice highest |
Cake:
Angel food, pound |
Chick-peas
(hummus) |
| Carrots |
Cereal:
Shreded Wheat, Special K, muesli |
Energy
bars: Balance, Clif, Harvest, Ironman, PR, PowerBar,
PureFit |
| Couscous |
Cheese
pizza |
Fruit,
dried: apricots, cherries |
| Cream
of Wheat (instant) |
Cheese
tortellini |
Fructose |
| Fruit:
cantaloupe, pineapple, watermelon |
Corn
(sweet) |
Fruit:
apples, grapefruit, grapes, oranges, peaches, pears,
plums, strawberries |
| Fruit,
dried: dates, raisins |
Fruit:
kiwi, mango, papaya |
Juice:
apple, grapefruit |
| Donuts,
pastries |
Fruit
cocktail (canned) |
Lima
beans (baby) |
| Graham
crackers, vanilla wafers |
Ice
cream (low-fat) |
Milk:
fat-free plain, chocolate or soy |
| Glucose,
sucrose (table sugar) |
Muffin:
bran, blueberry |
Oatmeal
(old-fashioned) |
| Honey |
Oat
bran |
Peanuts |
| Pancakes,
waffles |
Oatmeal
cookies |
Pasta:
Whl wht or w/>10g protein |
| Potatoes,
French fries |
Orange
juice |
Rice
bran |
| Pretzels,
corn chips |
Pasta
<10g protein |
Tomato
soup |
| Rice
(instant) |
Popcorn |
Yogurt,
low-fat (no sugar) |
| Rice
cakes |
Potato
chips |
|
| Rice
pasta |
Rice:
basmati, brown and white |
|
| Saltines,
Wheat Thins |
Sweet
potatoes |
|
| Soda,
most sport drinks |
|
|
| Tofu
frozen desserts |
|
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Kim Mueller, M.S., R.D., is a sports
dietitian and competitive endurance athlete who provides nutritional
counseling and meal planning to athletes worldwide. Visit www.kbnutrition.com
for more information, or e-mail her at kim@kbnutrition.com.
Take your nutritional plan as seriously
as your training plan in order to perform at your best.
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