Nutrition for Athletes

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

Easy 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

Recommendations for Athletes Carbohydrate intake Pre-exercise meal Carbohydrate loading Protein intake Fat intake

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 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

Carbohydrates 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? 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 Recommendations 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 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: One 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

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 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

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 (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 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 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 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 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

Creatine 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?

Creatine 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

Creatine 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! 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)