Exercise Testing and Prescription: A Health-Related Approach by Nieman. McGraw-Hill, 2006.© Nutrition and Performance

Exercise Testing and Prescription: A Health-Related Approach by Nieman. McGraw-Hill, 2006.©

Nutrition and Performance


Questions about sports nutrition• Can diet improve athletic

endeavor?• What is the optimal diet for

athletes?• Does exercise increase the need

for vitamin and mineral supplements?

• Do athletes (relying on strength and power) need protein supplements to maximize size and power?

• What ergogenic aids are safe and beneficial?


Principles of Sports Nutrition

• A healthy, balanced diet is the cornerstone

• Increase total energy intake to adjust for calories burned during exercise

• Keep dietary carbohydrate intake high (55-70%)

• Drink large amounts of fluid• Vitamin & mineral supplements

are not needed• Ergogenic aids are unethical


2005---USDA Dietary Guidelines• WEIGHT MANAGEMENT;

PHYSICAL ACTIVITY

Key Recommendations (Coaches)• To maintain body weight in a healthy

range, balance calories from foods and beverages with calories expended.

• To prevent gradual weight gain over time, make small decreases in food and beverage calories and increase physical activity.


2005 Guidelines (Coaches):WEIGHT MANAGEMENT; PHYSICAL ACTIVITY (cont)

• Engage in regular physical activity and reduce sedentary activities to promote health, psychological well-being, and a healthy body weight. – To reduce the risk of chronic disease in adulthood: Engage in at least 30

minutes of moderate-intensity physical activity, above usual activity, at work or home on most days of the week.

– For most people, greater health benefits can be obtained by engaging in physical activity of more vigorous intensity or longer duration.

– To help manage body weight and prevent gradual, unhealthy body weight

gain in adulthood: Engage in approximately 60 minutes of moderate- to vigorous-intensity activity on most days of the week while not exceeding caloric intake requirements.

– To sustain weight loss in adulthood: Participate in at least 60 to 90 minutes of daily moderate-intensity physical activity while not exceeding caloric intake requirements. Some people may need to consult with a healthcare provider before participating in this level of activity.


2005 Guidelines:FOOD GROUPS TO ENCOURAGE

• Consume a variety of fruits and vegetables (2 cups fruit, 2 ½ cups vegetables per day for a 2,000-calorie intake (higher or lower depending on the calorie level).

• In particular, select from all 5 vegetable subgroups (dark green, orange, legumes, starchy vegetables, and other vegetables) several times a week.

• Consume 3 or more ounce-equivalents of whole-grain products per day, with the rest of the recommended grains coming from enriched or whole-grain products (at least half the grains should come from whole grains).

• Consume 3 cups per day of fat-free or low-fat milk or equivalent milk products.


Visit www.mypyramid.gov for details (and to choose your food intake plan).

Physical activity

Grains

vegetables

fruits oils

milk

meat and beans

http://www.mypyramid.gov/


2005 Guidelines:CARBOHYDRATES

• Choose fiber-rich fruits, vegetables, and whole grains often.

• Choose and prepare foods and beverages with little added sugars or caloric sweeteners, such as amounts suggested by the USDA MyPyramid and the DASH Eating Plan.

• Reduce the incidence of dental caries by practicing good oral hygiene and consuming sugar- and starch-containing foods and beverages less frequently.


2005 Guidelines: FATS• Consume less than 10% calories from saturated fatty acids

and less than 300 mg/day of cholesterol, and keep trans fatty acid consumption as low as possible.

• Keep total fat intake between 20 to 35% of calories, with most fats coming from sources of polyunsaturated and monounsaturated fatty acids, such as fish, nuts, and vegetable oils.

• When selecting and preparing meat, poultry, dry beans, and milk or milk products, make choices that are lean, low-fat, or fat-free.

• Limit intake of fats and oils high in saturated and/or trans fatty acids, and choose products low in such fats and oils.


2005 Guidelines:SODIUM AND POTASSIUM

• Consume less than 2,300 mg (approximately 1 tsp of salt) of sodium per day.

• Choose and prepare foods with little salt. At the same time, consume potassium-rich foods, such as fruits and vegetables.


2005 Guidelines: ALCOHOLIC BEVERAGES

• Those who choose to drink alcoholic beverages should do so sensibly and in moderation—defined as the consumption of up to one drink per day for women and up to two drinks per day for men.

• Alcoholic beverages should not be consumed by some individuals, including those who cannot restrict their alcohol intake, women of childbearing age who may become pregnant, pregnant and lactating women, children and adolescents, individuals taking medications that can interact with alcohol, and those with specific medical conditions.

• Alcoholic beverages should be avoided by individuals engaging in activities that require attention, skill, or coordination, such as driving or operating machinery.


The Most Important Sports Nutrition Principle for Athletes: Increase intake of

carbohydrate (55-70%)• Muscle and liver glycogen (stored

carbohydrate) found to play important role in intense exercise.

• Exhaustion is tied to low muscle glycogen levels and is limiting in bouts lasting longer than 60-90 minutes.

• When muscle and liver glycogen is low, a high work output cannot be maintained.


Second Most Important Sports Nutrition Principle: Increase Fluid Intake

• As the muscle burns fuel, 70-80% is transformed into heat (body heat can rise 1°C/5 min, causing death in 20-30 min).

• During exercise, sweat evaporation accounts for >80% of heat loss (1 liter of sweat evaporation on the skin removes 600 kcal heat).

• Sweat losses can range from 0.5-3.7 l/hr (avg. 32oz/hr) of exercise, depending on the work rate and environmental conditions.

• Loss of >2% body water impairs performance (e.g., 3 lbs in a 150 pound athlete).


ACSM Position Stand on Exercise & Fluid Replacement

• Emphasize fluid intake before exercise by drinking adequate fluids during the day before the event, and drink about 500 ml (about 16 oz) two hours before exercise.– Urine should be light-colored, good volume, no strong smell.

• Athletes should start drinking early and at regular intervals during exercise to replace nearly all the water lost from sweating.– 0.5-2 cups fluid/ 10-15 min of exercise – 2 cups / pound of weight loss – Gastric emptying is promoted by >600 ml gastric volume

(maintain largest fluid volume in stomach that is tolerable)It’s better to gulp 16oz as opposed to sipping fluids

– Fluids should be sweetened (6-8% carb), flavored, and cooled to stimulate intake (Gatorade is 6% and Powerade is 8%)


ACSM Position Stand on Exercise & Fluid Replacement (cont.)

• If the event is longer than 1 hour, carbohydrates and electrolytes should be included in fluids ingested.

• Carbohydrates should be ingested at a rate of 30-60 g/hr (0.6-1.2 liters or 16-32 oz) of most sports drinks with 4-8% carb)

• Inclusion of sodium (0.5-0.7 g/l water) enhances palatability, promotes fluid retention (less urination), and helps prevent hyponatremia in certain athletes who drink excessive plain water during ultra events– 1 liter sweat has 0.4-1 g sodium


Vitamin and Mineral Supplements Are Not Needed

In a joint statement, the American College of Sports Medicine, American Dietetic Association, and Dietitians of Canada have stated,

“In general, no vitamin and mineral supplements should be required if an athlete is consuming adequate energy from a variety of foods to maintain body weight. If an athlete is dieting, eliminating foods or food groups, is sick or recovering from injury, or has a specific micronutrient deficiency, a multivitamin/mineral supplement may be appropriate. No single nutrient supplements should be used without a specific medical or nutritional reason (e.g., iron supplements to reverse iron deficiency anemia).”


ADA Summary on Protein Intake

• “Recommended protein intakes can generally be met through diet alone, without the use of protein or amino acid supplements, if energy intake is adequate to maintain body weight...Athletes should be aware that increasing protein intake beyond the recommended level is unlikely to result in additional increase in lean tissue because there is a limit to the rate at which protein tissue can be accrued...Although the protein quality of a vegetarian diet is adequate for adults, plant proteins are not as well digested as animal proteins. Thus, to adjust for incomplete digestion, an increase of about 10% in the amount consumed may be made.”


Use of ergogenic aids usually have little or no value and in

some cases are illegal• Ergogenic = substances or methods that

tend to increase performance capacity– Nutritional aids (carbohydrates, vitamins,

proteins)

– Pharmacological aids (steroids, amphetamines)

– Physiological aids (oxygen, blood doping)

– Mechanical aids (biomechanical aids)


Nutritional Ergogenic Aids • Prohormones: compounds such as androstenedione,

androstenediol, and dehydroepiandrosterone that are purported to increase testosterone, improve recovery, and build muscle mass.

• Creatine preparations: supplements that contain creatine monohydrate, and are advertised to improve power performance and build muscle mass.

• Proteins and amino acids: claimed effects include increases in muscle mass, strength, and endurance.

• Natural and herbal products: ginseng, Echinacea, saw palmetto, tribulus, and kava kava which are claimed to improve energy, strength, endurance, and immune function.


Nutritional Ergogenic Aids (cont.)

• Diuretics: herbal diuretics and stinging nettle which purportedly prevent water retention, swelling, gout, and high blood pressure.

• Energy enhancers, vitamins, and antioxidants: vanadyl sulfate, taurine, and vitamins which are postulated to improve recovery, aid in rehydration and glycogen replenishment, and provide added energy.

• Mental enhancers: plant extracts, amino acids, alkaloids (ephedrines and caffeine), minerals, and vitamins that are alleged to modulate mood, boost metabolism, increase adrenaline output, and provide energy and power.

• Fat burners: L-carnitine, inositol, and choline that are asserted to increase lean muscle mass and burn fat.


ADA/ACSM Guidelines• The 1994 Dietary Supplement Health and Education Act

allows supplement manufacturers to make claims regarding the effect of products on the structure/function of the body, as long as they do not claim to diagnose, mitigate, treat, cure, or prevent a specific disease. Performance can be categorized as follows:– Those that perform as claimed.– Those that may perform as claimed but for which there is

insufficient evidence of efficacy at this time.– Those that do not perform as claimed.– Those which are dangerous, banned, or illegal, and

consequently should not be used.• Athletes should be counseled regarding the use of ergogenic aids,

which should be used with caution and only after careful evaluation of the product for safety, efficacy, potency, and legality.


Ergogenic Aids That Work??

• Steroids and Steroid-Like Compounds – Fact: Claims are true for most people who also engage in intensive

resistance exercise. Side effects are legion.

– Prohormones are a class of androgenic steroids that either convert to testosterone directly or mimic testosterone by forming androgen-like derivatives (e.g., nandrolone). These compounds include dehydroepiandrosterone (DHEA), androstenedione, 5-androstenediol, and 4-androstenediol, all now sold as prohormones in the U.S. marketplace. Most studies indicate that some androgen supplements convert to testosterone, but also estrogen subfractions. The net effect is no increase in protein synthesis, muscle mass, or strength.

– Claim: Increase muscle mass & strength, decrease fat mass, increase aggressiveness


• Doping with growth hormone:– Reputation of being effective in

building skeletal mass, reducing fat mass, and improving submaximal and maximal aerobic endurance among athletes.

– Crucial in energy metabolism and body anabolism, and has multiple benefits when administered to adults with growth hormone deficiencies.

– Currently, the effects of growth hormone in improving athletic performance, muscle strength, and recovery from intensive exercise are unproven, but studies are ongoing.


Ergogenic Aids That Work??• Creatine---ACSM consensus

statement– Creatine supplementation can increase

muscle phosphocreatine content, but not in all individuals.

– Exercise performance involving short periods of extremely powerful activity can be enhanced with creatine supplementation (e.g., 5-7 d of 20 g/d), especially during repeated bout of activity; does not increase maximal isometric strength, the rate of maximal force production, nor aerobic exercise performance. Effects are relatively small.

– Creatine supplementation leads to weight gain within the first few days; due to water retention.

Documents

Exercise Testing and Prescription: A Health-Related Approach by Nieman. McGraw-Hill, 2006.© Nutrition and Performance