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Nutrition and Nutritional
Supplements in Sports
Performance Influencing Factors
Genetics
Training and Conditioning
Nutrition
Determinants of the Athlete’s
Energy Requirements
During intense exercise
Carbohydrate stored in muscles and liver (glycogen) is predominant fuel source
During prolonged exercise
Fat stores are predominant fuel source
Fitness level of the athlete
Well trained endurance athletes burn fat more efficiently, sparing limited glycogen stores
Formula for Estimating the
Body’s Calorie Requirements
Sedentary person
Weight (kg) x 25
Moderately active person
Weight (kg) x 30
Active person (endurance athlete)
Weight (kg) x 40
Underweight person
Weight (kg) x 45
kg = lbs / 2.2
Carbohydrates
Non-essential nutrient (human body can make sugar)
Simple (sugars) and Complex (starches)
Major fuel source for exercising muscle
Athletes should ingest 6 to10 gm/kg/day
60 to 70% of total calories should come from carbohydrates
Complex carbohydrates (starches) are preferable
During exercise Athletes should consume 25 to 30 gm of carbohydrate for
every 30 minutes of exercise
Athletes should drink 6 to 8 ounces of water or sports drink for every 10 to 15 minutes of exercise
Carbohydrates
After exercise
Athletes should consume 1.0 to 1.5 gm/kg
immediately post exercise and again one
hour later
To replace muscle glycogen stores
To prevent gradual depletion of muscle
glycogen stores over time caused by repetitive
daily bouts of heavy exercise
To decrease muscle breakdown
Why Complex Carbohydrates?
Compared to ingesting simple carbohydrates,
ingesting complex carbohydrates:
Increases muscle glycogen stores better
Improves performance and delays fatigue
Promotes faster stomach emptying
Causes less stomach upset and indigestion
Leads to lower blood sugar and insulin levels
Provides other beneficial nutrients
Fiber, vitamins and minerals
Pre-exercise Meal
Importance
Less hunger before and during exercise
Maintains optimum glycogen stores
Recommendations
Emphasize complex carbohydrates (starches)
1 to 4 gm/kg about 1 to 4 hours prior to event
Consume less closer to event
Avoid high fat and high protein foods
Slower gastric emptying can cause stomach upset
Avoid high fiber or gas forming foods
Can lead to crampy abdominal pain
Carbohydrate Loading
Increases the body’s pre-exercise
glycogen stores by 50 to 100%
Benefits endurance athletes who
compete for longer than 90 minutes
Can increase endurance up to 20%
Can increase performance by 2 to 3%
Comparison of Diets
Low CHO diet (40%
kcal from CHO)
Double
cheeseburger
Medium fries
Chocolate
milkshake
High CHO diet
(70% kcal from
CHO)
12 inch sub
sandwich (lots of
vegetables & no
mayo)
500 ml apple juice
250 ml chocolate
milk
banana
20
40
60
80
100
120
140
Time
Mu
scle
Gly
co
gen
(m
M/k
g w
et
wt)
High CHO
Low CHO
Effects of Diet on Muscle Glycogen
Content
Carbohydrate Snacks
Foods supplying 50 grams CHO 500 ml juice
3 medium pieces of fruit
1 honey sandwich
2 breakfast bars
1 sports bar (check label)
1.3 bagels
1/2 cup dried fruit
1 cup white rice
1 baked potato
*average 70 kg endurance athlete should consume 560 grams CHO per day
Carbohydrate Loading:
One Example of How
Days prior to event Exercise duration Carbohydrate intake
6 90 minutes 5 gm/kg/day
5 40 minutes 5 gm/kg/day
4 40 minutes 5 gm/kg/day
3 20 minutes 10 gm/kg/day
2 20 minutes 10 gm/kg/day
1 rest 10 gm/kg/day
Protein
Athletes require more protein than non-athletes 12 to 18% of total calories should come from protein
Protein intake should be tailored to type of training 1.2 to 1.4 gm/kg/day recommended for endurance athletes
1.7 to 1.8 gm/kg/day recommended for strength athletes
Average American diet provides 1.4 gm/kg/day
Adequate calorie intake is just as important as adequate protein intake for building muscles
Too much protein intake can be bad Excess protein calories are stored as fat
Excess protein intake can lead to dehydration and may contribute to kidney problems
Fat
Major source of energy
25 to 30% of total calories should come from fat
Less than 10% of total calories should come from
saturated fats
Cholesterol intake should be less than 300 mg/day
Average American diet provides 37% of total
calories from fat
Nutritional Supplements
1994 Dietary Supplement Health and Education Act Definition of a supplement
Any product that contains vitamins, minerals, amino acids, herbs, botanicals or a concentrate, metabolite, constituent, extract or combination of any of these ingredients
Removed dietary supplements from FDA regulation on the front end
FDA must prove a supplement is dangerous before its sale can be prohibited
Nutritional Supplements
1994 Dietary Supplement Health and Education Act
Manufacturers do not have to provide scientific proof of claims
Manufacturers cannot state product is meant to diagnose, treat, prevent or cure a disease but can make indirect suggestions
Created a multi-billion dollar industry that continues to grow rapidly
Vitamins and Minerals
Essential nutrients Human body needs these to produce energy
No evidence in U.S. studies that taking vitamin and mineral supplements improves athletic performance Being deficient in vitamins or minerals is rare in the U.S.
compared to the rest of the world
A few studies outside U.S. showed an effect Did population studied have some baseline deficiency
treated with these supplements?
Vegetarian athletes are at risk for being deficient in vitamins B12, D, riboflavin, iron, zinc and calcium Athletes who are strict vegetarians should take a
multivitamin to prevent deficiencies and a calcium supplement (1000 mg/day) to help prevent bone loss
Conclusions
Nutrition plays an important role in an endurance athlete’s ability to perform
Proper nutrition in combination with sound and proven training techniques can help endurance athletes to maximize their genetic abilities
Certain nutritional supplements have not demonstrated any performance benefit in studies
Conclusions
Certain nutritional supplements can have potentially dangerous side effects
Further legislation is needed to address the dangers of some nutritional supplements
Professionals in the community need to be resources of good information for athletes, parents and coaches Physicians
Physician assistants
Nurse practitioners
Athletic trainers
School nurses
Dieticians