Chapter 6

Nutritional Considerations

Eating for Sport Performance• American Dietetics Association indicates that eating

properly will:• help you train longer and at a higher intensity• delay the onset of fatigue• promote recovery• help your body adapt to workouts• improve body composition and strength• enhance concentration• help maintain healthy immune function• reduce the chance of injury• reduce the risk of heat cramps and stomach aches.

Nutrition

• Diet influences every aspect of sports participation.• Certified athletic trainers are most

knowledgeable about nutrition.• Coaches and athletes often lack adequate

nutrition information and incorporate unfounded nutritional practices into training programs.

Knowledge of Nutrition

• Recent studies (Jacobson et al., 2001; Froiland et al., 2004)

• Demonstrated that athletes may be receiving better nutritional education from more reliable sources.

• But there is still education to be done because Jacobson et al (2001) reported that only 55% of college athletes received nutritional advice always or often during their college careers

Overview of Nutrients

• Macronutrients• Carbohydrates• Fats (Lipids)• Protein

• Micronutrients• Vitamins• Minerals

• Water

Carbohydrates

• Carbohydrates (CHO) provide energy for high-intensity exercise• Experts recommend 60% to 70% of daily calories

be supplied by CHO.• Each gram of CHO provides 4 kilocalories.• Average person stores approximately 1500 to

2000 kcals of CHO, the majority of which is in the form of muscle and liver glycogen. Small portion available as blood glucose.

• Carbohydrate loading can benefit athletes involved in aerobic sports, especially activities lasting 60 minutes or more.

Carbohydrates

• CHO derived from plant sources, primarily grains, seeds, fruits, and vegetables.

• Simple CHO – monosaccharides• Typically stimulate insulin release and blood glucose

fluctuations.

• Foods containing are high caloric and often referred to as empty calories.

• Complex CHO – polysaccharides• Whole-grain cereals & breads, vegetables, and fruits.

• Dietary fiber (indigestible CHO) essential for digestion.

Carbohydrates

• Simple and complex CHO are suitable to describe foods, but these do not represent the way they are hydrolyzed and absorbed by the body. • Low Glycemic Index CHO

• Cause a steadier rise and decline in blood glucose and insulin. Best for weight management and overall diet.

• High Glycemic Index CHO• Typically result in a large and rapid rise in blood

glucose and insulin, followed by a rapid decrease in blood glucose. Best for refueling after event.

Fats

• Fats (lipids) are needed for energy, insulation, and protection of organs.

• Experts recommend that fats compose 30% or less of total calories.

• Each gram of fat supplies 9 kilocalories.• Fatty acids and glycerol make up fats.

Fats• Fatty acids can be saturated or unsaturated.

• Saturated - all of the available bonding sites on the fatty acid molecule are occupied by a hydrogen atom. Derived from animal sources (i.e., beef, pork, poultry, and dairy products). Generally solid at room temperature.

• Unsaturated fats are structured in such a way as to prevent all of the available bonding sites from being occupied by a hydrogen atom. Plant based. Generally liquid at room temperature.

Proteins• Proteins are needed for tissue construction, enzyme

reactions, and energy during prolonged exercise.• Experts recommend that proteins compose 10-15%.• Each gram of protein supplies 4 kilocalories.• Proteins are composed of amino acids

• 20 different amino acids are used to make thousands of proteins.

• 8 are essential amino acids, which cannot be synthesized by the body. Must be ingested in the diet

Proteins

• Sources include eggs, meats, dairy products, legumes, or grains.

• Athletes who are on vegetarian diets must take care to eat foods in the correct combination to provide all of the essential amino acids.• A solution to the problem is for such athletes to

include either eggs (ovolactovegetarian), milk products (lactovegetarian), or both to ensure adequate supplies of essential amino acids.

Protein Supplementation• Protein supplementation is not recommended

because:• Increase saturated fat in the diet• Overstress the liver and kidneys.

• NO scientific evidence that protein supplements enhance muscles.

• During intense training, 1.2-1.8 grams protein/kg body weight are recommended.• 0.83-1.2 g/kg for sedentary or light exerciser

• Normal diet provides adequate protein consumption for intense training.

Vitamins• Vitamins have various functions

• Regulate biochemical reactions (energy metabolism and cell and tissue generation)

• Serving as antioxidants that protect cell structure.

• Vitamins contain no caloric value and a balanced diet supplies the RDA.

• There are water- and fat-soluble types of vitamins. • Water soluble: Vitamins C, B1, B2, B6, B12, niacin, folic acid,

biotin, and pantothenic acid. • Fat soluble: vitamins A, D, E, and K.

Minerals• Minerals are elements needed for various body

functions.• Provide structure, help maintain normal heart

rhythm, assist muscle contractility, promote neural conductivity, and regulate metabolism.

• There is no scientific evidence to support taking minerals in excess of RDA for performance.• But endurance athletes may be at an increased risk

of iron or calcium deficiency • Iron and Calcium RDAs

• Iron:10 mg for males and 18-20 mg for females• Calcium: 1500 mg

Vitamins and Minerals• Athletes who do not eat a balanced diet

should be advised to include a vitamin and mineral supplement.

• A convenient method of supplementation is a daily multivitamin.

• But megadoses of vitamins/minerals should be avoided and could result in severe consequences.

Water (H2O)• Water is necessary for human performance, as

well as survival.• Adult water requirement at rest is approx. 2.5 liters

daily, but it can increase to 5–10 liters during heavy exercise, especially in high temperature and humidity.

• Water lost during exercise needs to be replaced to maintain body’s fluid balance. • A reduction of body weight of 2-5% can impair function. • Current recommendations are for every 1 lb lost due to

sweating, 20-24 oz. of water be consumed.

Dietary Habits of Athletes

• Seventy percent of university athletes are falling short of their daily caloric needs and 81% of females and 90% of males were not eating the recommended amounts of CHO. (Hilton, 2005).

• Collegiate athletes underestimate their carbohydrate needs and overestimate their fat and protein needs.• In fact, 21% believed that protein provides immediate

energy and 30% thought that vitamins provide immediate energy. (Jacobson et al., 2001)

Dietary Habits of Athletes• Conclusions

• Many athletes do not consume proper proportions of CHO, fat and protein.

• Many tackle football players consume diets high in protein and fat.

• Athletes in sports that require lean bodies tend to eat diets with insufficient calories.

• Most athletes’ diets are deficient in important minerals, i.e., calcium, iron, & zinc.

• Athletes eat too much “junk food.”

Weight Loss and Wrestling

• Wrestling is one of only a few sports that match participants on the basis of weight.

• Wrestlers often follow unhealthy weight loss procedures to compete in lighter weight categories.

• Rapid weight loss occurs via dehydration.• Dehydration occurs through the use of

laxatives and diuretics, fluid restriction, artificially induced sweating, and starvation.

Weight Loss and Wrestling

• Short-term effects of repeated bouts of extreme weight loss include:

• Increased blood viscosity.• Blood clots.• Kidney and liver problems.• Ulcers.

• Long-term effects may include interference with normal growth and development.

Wrestling Minimum Weight Project (WMWP)

• Wisconsin instituted WMWP in 1989.• Weight loss must be no more than 3 lbs. of

weight loss/week. • A minimum 7% body fat level was

established.• Testing of athletes along with nutrition

education for coaches was implemented.

WMWP

• The NFSH has developed a national wrestling rule #1-3-1 that states: • “A medical professional should…establish

a minimum (wrestling) weight through… checking body fat and hydration. The recommended minimum body fat should not be lower than 7%.”

What Can the Coach Do?

• Coaches are an important source of nutrition information.• People planning to enter the coaching

profession should take at least one basic college nutrition course.

• Attend in-service meetings, professional conferences, or community education programs in sports nutrition.

• Subscribe to professional journals that include nutrition articles.

What Can the Coach Do?• Locate nutrition experts, including dietitians,

university nutrition faculty, or sports medicine staff. • Implement peer-led programs like Athletes

Targeting Healthy Exercise & Nutrition Alternatives (ATHENA). (Eliot et al., 2008)

• Have athletes keep a record of their diet that is reviewed periodically by a person knowledgeable in nutrition.

• When working with children, discuss nutritional needs of the athlete with parents.

General Dietary Guidelines for Athletes

• Three Goals• Nutritional maintenance and development

during training• Pre-competition preparation• Nutrition during competition

MyPyramid, www.MyPyramid.gov

Sports, Cardiovascular, and Wellness Nutrition practice group (http://www.scandpg.org)

Nutrition During Training• Recommendations include:

• Tailoring an athlete’s diet to meet individual needs • Consuming: 10-15% calories from protein, 30%

from fat, and the remainder from CHO (>55%).• 1.5-2.0 grams of protein/kg of body weight/day. • Little need for vitamin/mineral supplements if diet

is well balanced.• Using simple terms when educating young

athletes about nutrition.

Pre-competition Diets

• Experts recommend that the typical pregame meal should be eaten no later than 3 to 4 hours prior to the contest.

• Eat low-fat, easy-to-digest foods.• Liquid meals increase hydration and are less

likely to cause bloating or “heavy” feeling.• Foods should provide 150 to 300 grams of

CHO or 3 to 5 grams/kg of body weight.

Nutrition During Competition

• One hour of highly intense exercise can reduce liver glycogen by 55% and 2 hours can almost completely deplete both liver and muscle glycogen.• CHO consumption during long-duration exercise

(1 to 3 hours at 70% to 80% VO2max ) allows muscle cells to rely on blood glucose for energy.

• Recommended fluid source of CHO is 8 oz. of a 5% CHO solution consumed every 15-20 min.

Nutrition After Competition• Dietary goals are to replace muscle glycogen and

ensure quick recovery. • A carbohydrate intake of approximately 1.0–1.5 g/kg body

mass (0.5–0.7 g/lb) during the first 30 min and again every 2 h for 4–6 h will be adequate to replace glycogen stores.

• Timing of CHO ingestion is important as glycogen levels will replenish faster if the food is consumed within 30 minutes – 1 hour.

• Protein consumed after exercise will provide amino acids for building and repair of muscle tissue.

Weight vs. Fat Management

• Body weight consists of water, fat, and lean tissue.• Muscle is denser than fat

• In order to maintain weight an athlete’s caloric intake must equal caloric expenditure.• Consume more calories per day than the body requires

then excess calories are converted to fat.• Fail to consume enough calories to meet the daily

requirement then stored fat will be metabolized to form energy.

• Severe caloric restrictions (fasting) result in protein breakdown.

Weight vs. Fat Management

• Percentage of body fat = the ratio of fat to lean body weight • Better measurement for weight management and is

commonly referred to as body composition.

• Ranges for most active young females are 10-28% and active young males are 5-15%. • Males should have at least 5% body fat.• Females should have a minimum of 8 to 10% body fat.

• Percent body fat can be used to accurately calculate an athlete’s minimal competitive weight so they can excel during the season.

Minimal Competitive Weight (MCW)

• Athletes should only weigh themselves once/week at the same time of day and after going to the bathroom.

Sample Equation: [MCW = LBW/% fat desired]• Determine % fat desired (5%); (1 - % fat

desired = 0.95)• A 135 lb athlete with 14% body fat has lean

body weight (LBW) = 135 x 0.14 = 18.9 lb fat• 135 lb – 18.9 (fat weight) = 116.10 lb (LBW)• MCW = 116.10/0.95 = 122 lbs

Supplements and Ergogenic Aids

• Supplements have become very popular with athletes of all calibers.

• Supplements can be divided into two categories: Legal and Illegal.

• Legal supplements: caffeine, creatine, amino acids, and herbal supplements.

• Illegal supplements: anabolic steroids, androstenedione, EPO, GHB, human growth hormone.

• It is important for the consumer to evaluate the marketing claims, research studies, and safety issues associated with ergogenic aids. (Manore, Meyer, and Thompson, 2009)

• Several studies have identified unrecognized risks of supplementation, so consumers should be aware of deceptive marketing techniques including outstanding claims, patents, testimonials, and media campaigns.

Supplements and Ergogenic Aids

Most Popular Legal Supplements

• Caffeine• Touted to be a safe aid and can provide a boost of energy

for the athlete. It is purported to aid endurance activities by assisting substrate metabolism and delaying fatigue.

• Ephedra• Stimulant - affects the way the brain recognizes

exhaustion during exercise • Very controversial ergogenic aid and has recently been

banned because it was linked with over 155 deaths (Hampton, 2005)

Most Popular Legal Supplements

• Creatine• Has been found to be more helpful for athletes who use

short bursts of energy than for endurance athletes.• Produces an increase in energy at the cellular level which

allows the athlete to train for longer periods of time.• Adverse effects associated with creatine are kidney

damage, fluid retention, muscle cramps, upset stomach, and diarrhea.

• There are many published studies on creatine use but they report conflicting results.

Most Popular Legal Supplements • Amino Acids

• Marketed for muscle building and repair.• Isolated amino acids used for the purpose of muscle building

are NOT effective.

• Water soluble and cleared and eliminated through the kidneys and urine. Excess can apply extra stress to the urinary system and result in permanent damage.

• Herbal Supplements• Herbs produce a stimulatory effect (ginseng, yohimbe,

kava) and others produce relaxation to reduce stress in the athlete (chamomile, St. John’s wort).

• Drug interactions are possible with other medicines.

Illegal Supplements• High doses of anabolic steroids

• Athletes can contract blood borne diseases, damage internal organs, increase risk of heart attack, develop aggression and secondary sex characteristics.

• Erythropoietin (EPO) • Stimulates red blood cell proliferation. • May take too much and get too many red blood cells

circulating. Increases the viscosity of the blood = heart working harder = potential heart failure.

• Amphetamines - Stimulant• Gammahydroxybutyrate (GHB) - Depressant

Nutrition and Injury Recovery

• Weight gain can occur with forced inactivity due to injury.

• Recommend cross training during recovery.• Runners can ride stationary bikes or run in

swimming pools.• Maintains aerobic fitness while burning

excess calories.• Athletes who are ill/injured should reduce

total caloric intake until healthy to avoid excess weight gain.