Eating for Performance (Nutrition for Runners) was presented at the UCSF RunSafe Clinic in Feb 2012. It shows current nutritional research and data to achieve optimal performance and quick recovery after prolonged exercise, in particular running.
1. Eating for Performance
Andrea Hacker MS, RD
PhD candidate UC Davis
Dietitian UCSF RunSafe
2. Carbohydrates - Review
What are they and Why they are important
Carbohydrates are your body’s primary food source
Carbs restore muscle energy stores depleted by the
demands of training
Complex vs. Simple Carbs
Complex carbs are pasta, beans, bread
Remember to choose whole wheat!
Simple carbs are sugary sweets – candy, soda, fruit drinks
Limit these in your diet
5. Glucose Use During Physical
Activity
Glucose is stored in the liver and
muscles as glycogen
During activity liver breaks down
glycogen into glucose and
releases into blood stream
Glycogen stores are limited to
less than 2000kcals of energy
When muscle glycogen stores
are depleted the muscles
become fatiqued
6. Glucose use during activity
Diet affects glycogen storage and use
How much carb a person eats influences how much is stored.
A high carb diet enhances endurance by enlarging glycogen
stores
Intensity of Activity
Moderate activities use glycogen slowly, also using fatty acids
Intense activities use glycogen quickly
Lactic Acid
The product of anaerobic glycolysis (glucose breakdown)
At low intensities is readily cleared, at higher intensities it
accumulates
Liver recycles it to glucose
7. Glucose for use during
physical activity
Duration of activity
Within the first 20 minutes of moderate activity a person
uses mostly glycogen
After 20 minutes of moderate activity less glycogen is used
and more fatty acids
Glucose depletion
After muscle and glycogen stores are depleted nervous
system function comes to a near halt
Endurance athletes try to prevent this depletion by
Eating a high carb diet
Consuming glucose during the activity
Eating carbs immediately after activity
Training muscles to store as much glucose as possible
8. Glucose Use
Diet affects glycogen storage and use
Copyright 2005 Wadsworth Group, a division of Thomson Learning
9. Recommended Daily
Carbohydrate Intake for Athletes
Moderate training – exercising regularly, 5d
wk, 45min/d
5-7g carb/kg body weight
Endurance training – exercising 5d wk, 60min
to 4hr
7-10g carb/kg body weight
Ultra endurance training – exercising 5d wk,
more than 4hr
11g carb/kg body weight
10. Eating for Performance
Before Practice or Competition
Eating a full meal at least 3 hours before a game or practice is enough time for the
food to digest.
A high carbohydrate meal with a little fat is ideal for pre practice or competition
Eating sugar (candy, sweets, soda) before practice or competition can cause fatigue
and thirst
Early Morning Event
High carbohydrate meal night before
Early AM (6:00 am) light (~500 kcal) meal
Cereal, yogurt, fruit, sport bar (~70+ grams CHO)
Events at other times
Eat every 3 hours as normal
Have last meal 1.5 – 2 hours before the start
Meals should be low fat and rich in carbs
12. Eating for Performance
During Practice or Competition
Optimally, 15-20 CHO grams every 20 minutes
Food Suggestions:
½ Power Bar, 1 banana, ½ granola bar
Optimally, 4-8 ounces of fluid every 20 minutes
Less than 8% CHO liquid solution (sport drinks are best choice)
16 oz Gatorade has 30 grams CHO as well
More during hot & humid conditions
Plenty of fluids, for events >90 min Carb-based sports
drinks help to replace fluids and electrolytes, delaying
fatigue.
Remember to eat immediately following to replenish
your muscles!
13. Recovery from Practice or Competition
Eat as soon as you can after practice or competition.
Eating a high-carb meal will ensure a quick recovery. The
muscles need the carbohydrate to begin replenishing spent
glycogen stores
Recommendation
Eat around 200 calories within 30 minutes of finishing
a long run
Primarily carbohydrate with some protein
Suggestions: Chocolate milk, bread + peanut butter,
cereal and milk, banana + almonds
A small amount of protein added to the post practice or
competition meal will help to increase the muscles ability to
restore its energy stores
14. Hydration & Dehydration
In healthy individuals water intake
is controlled mainly by thirst. Water
is ingested as fluid and also as part
of foods
The body can not store water so
the amount of water lost every 24
hours must be replaced to maintain
health and body efficiency
Signs of dehydration
Concentrated urine
Decrease urine output
Dry mouth
Increased heart rate
Poor skin turgor
Skin tenting on the forehead
Sunken eyes
.
15. Fluids and Electrolytes for
Physical Activity
The need for water surpasses the need for any other nutrient
Water loss of 1-2% can reduce performance
Water loss of 7%, a person is likely to collapse
Fluid losses via sweat
Muscles produce heat as a by product of metabolism
During activity can produce 15-20 times more heat than at rest
The body cools itself by sweating
Each liter of sweat uses 600kcals and prevents an 18 degree raise
in body temp
16. Fluid during Physical Activity
Fluid replacement
Endurance athletes can lose 1.5 liters or more of fluid during
each hour of activity
During warm weather the GI tract may not be able to absorb
enough water fast enough to keep up with sweat losses
Water
Everyday noncompetitive active individuals
Rapidly leaves the GI tract to enter tissues
Cools body from the inside out
Sports drinks
Endurance athletes
Provides fluid and carbohydrate
17. Fluid during activity
Electrolyte replacement
When a person sweats, small amounts of electrolytes are lost
from the body
Sodium, potassium, chloride, magnesium
In events lasting greater than 1 hr electrolytes need to be
replenished
Hyponatremia
Endurance events lasting longer than 3 hours
Decrease concentration of sodium in the blood
Exercise intensity, heat, humidity can affect sweating
Sweat rates can exceed 3 liters per hour
Drinking large amounts of water causing over-hydration
Headache, vomiting, bloating/puffiness, confusion
18. Hydration Guidelines for
Performance - Endurance
Before
Drink at least 8 to 16 oz of fluid 2 hours before practice or
competition
Drink at least 4 to 8 oz of fluid immediately before exercise
During
Drink at least 4 to 8 oz of fluid every 15-20 min during training
and competition
After
Drink at least 8 to 16 oz of fluid after exercise
Daily
Drink at least 8 oz of fluid with each meal
Drink at least 8 oz of fluid between meals
19. Fluid and Physical Activity
Alcohol Water
Dehydrating, impairs Hydrates and cools the
body’s ability to regulate body
body temp, hinders Sports beverages
performance
Hydrates and cools the
Caffeine body, provides glucose
Not as hydrating as and electrolytes
water, may limit
performance
Notas do Editor
Since carbs are the typical limiting energy substrate (it will run out before fat or protein) in exercise, starting exercise with more of it in tissues should aid exercise endurance. When carb stores are depleted you quickly become fatigued and performance drops dramatically.
Glycemic index High glycemic index foods enter the blood quickly and are better able to resynthesize live and muscle glycogen Higher glycemic index foods – carrots, honey, rice, potatoes Lower glycemic index foods – peanuts, milk, yogurt, apples, beans
Don’t try something new for competition. Rehearse what you intend to do for competition during practice. early am- Get up 2-3 hours before. Finish eating 1.5 hr before the start Make sure you have a full tank of fluid and carb Practice your eating schedule before competition
Total body water is higher in athletes than nonathletes Athletes can lose 3-4 lbs during practice at 80 F and low humidity, and even more at higher temperatures. Athletes need to rehydrate on a timed basis rather than as a reaction to thirst. Thirst is not a good indicator of hydration. A 2% loss of body weight results in impaired performance. It appears that plain water is not the best beverage to consume following exercise to replace the water lost as sweat. The replacement of electrolytes as well as water is essential for effective rehydration Fluid intake is essential for maintaining a body temperature that maximizes performance Increase fluids 24-hours prior to practice or competition. Water is the best fluid to consume prior to practice or competition Avoid sodas and fruit juices before and during practice or competition. Can lead to hyperglycemia, fatigue and bloating Excess salt can exacerbate dehydration
Make sure that you enter competition well hydrated Clear urine