Nutrition for Athletes

Determinants of the Athlete’s Determinants of the Athlete’s Energy RequirementsEnergy 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

Easy Formula for Estimating the Easy Formula for Estimating the Body’s Calorie RequirementsBody’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

Recommendations for AthletesRecommendations for Athletes

• Carbohydrate intake• Pre-exercise meal• Carbohydrate loading• Protein intake• Fat intake

CarbohydratesCarbohydrates

• Non-essential nutrient (human body can make sugar)• Simple (sugars) and Complex (starches)• Major fuel source for exercising muscle• Athletes should ingest 6 to10 g/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 g of carbohydrate for every 30

minutes of exercise (100-120kcal)– Athletes should drink 6 to 8 ounces of water or sports drink for

every 10 to 15 minutes of exercise

CarbohydratesCarbohydrates

• After exercise– Athletes should consume 1.0 to 1.5 g/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?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 MealPre-exercise Meal

• Importance– Less hunger before and during exercise– Maintains optimum glycogen stores

• Recommendations– Emphasize complex carbohydrates (starches)

• 1 to 4 g/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 cramping abdominal pain

Carbohydrate LoadingCarbohydrate 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%

Carbohydrate Loading:Carbohydrate Loading:One Example of HowOne Example of How

Days prior to event Exercise duration Carbohydrate intake 6 90 minutes 5 g/kg/day 5 40 minutes 5 g/kg/day 4 40 minutes 5 g/kg/day 3 20 minutes 10 g/kg/day 2 20 minutes 10 g/kg/day 1 rest 10 g/kg/day

ProteinProtein• 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 g/kg/day recommended for endurance athletes• 1.7 to 1.8 g/kg/day recommended for strength athletes

• Average American diet provides 1.4 g/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

FatFat

• 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 SupplementsNutritional 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 SupplementsNutritional Supplements• 1994 Dietary Supplement Health and Education

Act (USA)– 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

• Canada has implemented laws over the past 6 years much like the FDA but much stricter at the advertising level

Vitamins and MineralsVitamins and Minerals

• Essential nutrients– Human body needs these to produce energy

• No evidence in North American 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 North America 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

Vitamins and MineralsVitamins and Minerals

• Specific vitamins and minerals studied– Vitamin A and Vitamin D

• No evidence of increased performance• May have toxic effects at high doses

– Vitamin E• No evidence of increased performance• Toxic effects are rare

– Vitamin C• Anti-oxidant effect may help decrease exercise related muscle

soreness• No effect on strength• Possible toxic effects at high doses

Vitamins and MineralsVitamins and Minerals

• Specific vitamins and minerals studied– Vitamin B6

• No evidence of increased performance• Toxic over 200 mg/day (nervous system side effects)

– Other anti-oxidants (Betacarotene, Bioflavinoids, Copper, Cysteine and Glutathione)• May help to protect against exercise induced muscle damage• Study results are conflicting• Should not exceed 100% of the RDA of anti-oxidants

• Buyer beware!– Some supplements have been found to contain up to

3000% of U.S. RDA for vitamins and minerals

CreatineCreatine

• Chemical name: Creatine-Monohydrate• Naturally available in meat and fish• NCAA study found creatine supplements used by 12% of

college athletes• A subsequent survey of high school athletes showed

similar usage rates• Does it work to– Increase muscle mass?– Increase strength?– Increase performance?

• Is it safe?

CreatineCreatine• I found 9 studies showing (+) effects in healthy subjects published

between July 1997 and November 2001– Increased high intensity, intermittent exercise performance in squash

players– Increased cell hydration status and performance variables in Division I

college football players more than training alone– Augments repeated sprint cycle performance in hot environment

without altering thermoregulatory responses– Increases indices of high intensity exercise performance for both

males and females– Increased capacity of human muscle to perform work during

alternating intensity contraction

CreatineCreatine• Recent studies with (+) effects (continued)

– Ergogenic effect in elite ice hockey players– Loading improves intermittent sprint capacity at end of endurance

exercise to fatigue– Adding creatine to glucose, taurine and electrolyte supplement

promoted greater gains in fat and bone free mass, isotonic lifting volume and sprint performance during intense resistance and agility training

– Helped to prolong time maximal rate of power output could be maintained

Buyer Beware!Buyer Beware!

• IOC funded study by Shanzer (Germany) from 10/00 to 11/01– Analyzed 634 products labeled as non-hormonal nutritional supplements

from 13 countries and 215 different suppliers• 94 products (14.8%) were found to be “positive supplements” (contained

anabolic steroid precursors not declared on the label)• Anabolic androgenic steroid concentrations ranged from 0.01 to 190 micrograms

per gram of supplement• 23 products contained steroid precursors of nandrolone and testosterone• 64 products contained steroid precursors of testosterone only• 7 products contained steroid precursors of nandrolone only• Percentage of positive supplements per country

– 25.8% of products bought in Netherlands– 22.7% of products bought in Austria– 18.8% of products bought in UK– 18.8% of products bought in US (45 positive out of 240 tested)