Nutritional Factors in Health and Performance

Chapter 1O NSCA

Role of the Nutritionist

• Responsibilities of the nutritionist include the following:– Personalized nutritional counseling: weight

loss and weight gain, strategies to improve performance, menu planning, dietary supplements

– Dietary analysis of food records

– Nutritional education: presentations and handouts

– Referral and treatment of eating disorders

Nutrition and Role of the Personal Trainer

• It is well within the scope of practice of the personal trainer who possesses nutrition knowledge to address misinformation and to give advice as it relates to general nutrition for physical performance, disease prevention, weight loss, and weight gain

Nutrition and the Role of the Personal Trainer

• From the standpoint of both ethics and safety, referral to a nutrition professional is indicated when the client has a disease state (diabetes, eating disorder, heart disease, GI disease, elevated cholesterol…) that is affected by nutrition

• This type of nutrition information is called medical nutrition therapy and falls under the scope of a practicing licensed nutritionist or registered dietician

• American Dietetic Association’s Web site: www.eatright.org

Dietary Assessment• Before the personal trainer can assess a

client’s diet they need to extract the following information:

• What foods is the client allergic to?• Is the client a vegetarian?• Is he or she restricting food groups?• Dieting to lose weight?• Has the individual adopted a new way of

eating?• How many meals does she or he eat a day and

at what time?

Dietary Assessment

• The personal trainer has three methods of gathering dietary intake data to choose from:

– Dietary Recall

– Diet History

– Diet Records

Dietary Assessment• Dietary Recall: client reports what they

have eaten in the past 24 hours

• Diet History has clients answering questions about usual eating habits, likes and dislikes, eating schedule, weight history…

• Diet Record is a log filled out for three days, in which the client records everything consumed (foods, beverages and supplements)

Dietary Assessment• The Diet Record is considered the most

valid of the three methods for assessing the diet of an individual

• The Diet Record is worth it only if the client accurately and completely records usual intake for three days

• To get useful data, the personal trainer should only ask the most motivated clients to complete this process

• At best, dietary analysis gives a general idea of nutrient intake

How to Evaluate the Adequacy of the Diet

• Standard Nutrition Guidelines–Food Guide Pyramid

• Used to evaluate appropriate calorie level

• Used to evaluate appropriate nutrient levels to prevent nutrient deficiency or toxicity

• Developed by the U.S. Department of Agriculture in 1992

• Updated to MyPyramid in 2005

How to Evaluate the Adequacy of the Diet

• Standard Nutrition Guidelines–The color bands of MyPyramid

represent five food groups that are needed each day for health:• Grains

• Vegetables

• Fruits

• Milk

• Meat and beans

Figure 10.1

MyPyramid• Excellent starting point from which to

evaluate the adequacy of a client’s diet

• If a diet provides a variety of foods from each group, it is likely adequate for vitamins and minerals. However, if the diet excludes an entire food group, specific nutrients may be lacking.

• For more information and resources, go to www.mypyramid.gov

Energy

• Energy is commonly measured in calories

• Three factors make up the energy requirement of adults:

– Resting Metabolic Rate/Basal Metabolic Rate

– Physical Activity

– Thermic Effect of Food

Resting Metabolic Rate• The calories required to maintain normal

body functions such as respiration and cardiac function

• Factors that increase RMR are lean body tissue, young age, growth, abnormal body temperature, menstrual cycle, and hyperthyroidism

• Factors that decrease RMR are low caloric intake, loss of lean tissue and hypothyroidism

Energy

• The amount of energy needed for physical activity depends on the intensity, duration, and frequency of training

• Thermic effect of food is the energy needed to digest and assimilate food

Weight and Body Composition• Energy Requirements

–Estimating Energy Requirements

•Energy needs can be loosely estimated using the guidelines found in table 10.7

•Clients can also use food diaries during periods of stable body weight to estimate requirements

Weight and Body Composition

• Weight Gain–If all the extra calories consumed are used for muscle growth during resistance training, thenabout 2,500 extra kilocalories are required for each 1-pound (0.45 kg) increase in lean tissue

Weight and Body Composition• Weight Loss

– If all the expended or dietary-restricted kilocalories apply to body fat loss, then a deficit of 3,500 kcal will result in a 1-pound (0.45 kg) fat loss

– The maximal rate of fat loss appears to be approximately 1% of body mass per week

– This is an average of 1.1 to 2.2 pounds (0.5-1.0 kg) per week and represents a daily caloric deficit of approximately 500 to 1,000 kcal.

Weight Gain Versus Weight Loss• Gains in body mass and strength occur

when the client consumes adequate calories and dietary protein and engages in a progressive resistance training program.

• The most important goal for weight loss is to achieve a negative calorie balance.

• The types of foods the individual consumes are less important than the portions of those foods

• The focus is on calories

Weight and Body Composition

• Rapid Weight Loss–For clients who desire to minimize lean tissue loss, small decreases in caloric intake to achieve gradual weight loss are indicated

Protein• General Requirements

–Assuming that caloric intake is adequate and that two-thirds or more of the protein is from animal sources, the recommended intake for protein for adults is 0.8 g/kg (0.36 g/pound) of body weight for both men and women.

–Expressed as a percent of daily caloric intake, a common protein intake recommendation is 10% to 15%

Protein• Increased Requirements for

Athletes–Based on current research, it appears that the protein requirements for athletes are between 1.5 and 2.0 g/kg (more than 2.0 g/kg if you are vegan/vegetarian) of body weight, assuming that caloric intake and protein quality are adequate

Key Point • Recommendations to increase or

decrease protein intake should be made on an individual basis after the normal diet has been analyzed and caloric intake considered.

• A mixed diet is the best source of high-quality protein.

• Strict vegetarians must plan their diet carefully to ensure an adequate intake of all essential amino acids.

Carbohydrates• The primary role of carbohydrate in

human physiology is to serve as an energy source.–Provide 4 kcal/g– 50 to 100 grams (the equivalent of 3 to 5

pieces of bread) are needed to prevent ketosis

• Ketosis: incomplete metabolism of fatty acids. Ketosis occurs in diabetic patients or when not enough carbohydrates are eaten.

Carbohydrate Requirements

• A general recommendation is 8 to 10 g/kg of BW for aerobic endurance athletes (90 minutes or more daily)

• Intake of 5-6g/kg of BW is recommended if not training aerobically (90 minutes or more a day)

• Fiber

• There is no nutritional value for fiber

• The DRI for fiber is 38 and 25 g/day for young men and women, respectively.

• This level of fiber may be excessive for some aerobic endurance athletes.

Glycemic Index• The GI classifies a food by how high and for

how long it raises blood glucose.• The reference food is glucose or white bread

(GI = 100).• Foods that are digested quickly and raise

blood glucose (and insulin) rapidly have a high GI.

• Foods that take longer to digest and thus slowly increase blood glucose (and therefore stimulate less insulin) have a low GI.

Key Point

• Some aerobic endurance athletes have maximal carbohydrate requirements, up to 10 g/kg per day.

• Most athletes do not deplete muscle glycogen on a daily basis, however, and therefore have lower carbohydrate requirements.

Fat (Lipids) • Fat and Performance

–Intramuscular fatty acids are more important during activity

–Circulating fatty acids (from adipose tissue or diet) are more important during recovery

–Consumption of high-fat diets may enhance performance and result in longer distance to exhaustion

–The effects of high-fat diets vary, depending on the individual

Fat (Lipids)• A source of energy (9 calories per gram)

– Fat Requirements and Recommendations

• The recommendation for the general public from health organizations such as the American Heart Association is that fat should constitute 30% or less of the total calories consumed.

• It is recommended that 20% of the total calories (or two-thirds of the total fat intake) come from monounsaturated or polyunsaturated sources and 10% from saturated fats (one-third of total fat intake).

Fat (Lipids)• The Sub-Committee on Nutrition of the

United Nations recommends an upper limit for fat intake of 35% of total calories for active people.

• The American Heart Association and the Sub-Committee on Nutrition of the United Nations recommend that fat provide at least 15% of the total calories in the diets of adults and at least 20% of total calories in the diets of women of reproductive age.

When Should Athletes Decrease Dietary Fat?• Need to increase carbohydrate intake to support training

type

– In this case, to ensure adequate protein provision, fat is the nutrient of choice to decrease so that that caloric intake can remain similar while carbohydrate is increased.

• Need to reduce total caloric intake to achieve weight loss

– Because fat is dense in calories and is highly palatable, decreasing dietary fat, if the diet has excess fat, can help reduce caloric intake.

• Need to decrease elevated blood cholesterol

– Some young athletes are strongly predisposed to heart disease, although this is uncommon.

Micronutrients

• A micronutrient is a nutrient that is required in small amounts (typically measured in milligram—or even smaller—quantities) in the diet

• Two primary types of micronutrients are vitamins and minerals

Vitamins and Minerals• Vitamins

– Vitamins are organic substances (i.e., containing carbon atoms) that cannot be synthesized by the body.

– They are needed in very small amounts and perform specific metabolic functions.

• Minerals

– Minerals are required for a wide variety of metabolic functions.

– For athletes, minerals are important for bone health, oxygen-carrying capacity, and fluid and electrolyte balance.

Precompetition and Postexercise Nutrition

• Precompetition Food Consumption

– Purpose

• The primary purpose is to provide fluid and energy for the athlete during the performance.

– Timing

• The most common recommendation is to eat 3 to 4 hours prior to the event to avoid becoming nauseated or uncomfortable during competition.

Precompetition and Postexercise Nutrition

• Carbohydrate Loading: technique used to enhance muscle glycogen prior to long-term aerobic endurance training

• Eating 3 days of a high carbohydrate diet with tapering of exercise the week before competition

• 600 grams of CHO’s per day or 8-10 g per kg of body weight

• This should increase muscle glycogen stores 20-40% above normal

Precompetition and Postexercise Nutrition

• Consume carbohydrates immediately after exercise

• Consume moderate to high glycemic index carbohydrate-containing foods (50-75 g of carbohydrate each hour)

• With optimum carbohydrate intake, glycogen stores replenish at a rate of about 5 to 7% per hour

Precompetition and Postexercise Nutrition

• Postexercise Food Consumption– Data suggest that high-GI foods consumed

after exercise replenish glycogen faster than low-GI foods

– Although emphasis is usually placed on carbohydrate, in practical terms, consuming a balanced meal ensures the availability of all substrates for adequate recovery, including amino acids.

Fluid and Electrolytes

• Water–Water is the largest component of the

body, representing from 45% to 70% of a person’s body weight.

–Total body water is determined largely by body composition; muscle tissue is approximately 75% water, whereas fat tissue is about 20% water.

Fluid and Electrolytes• Water

–Fluid Balance

• The average fluid requirement for adults is estimated to be 2 to 2.7 quarts (1.9-2.6 L) per day

• Athletes sweating profusely for several hours per day may need to consume an extra 3 to 4 gallons (11-15 L) of fluid to replace losses

Water Recommendations• The basic goal of fluid intake is to

avoid dehydration• Dehydration is a state in which the

body tissues are deprived of water. It can occur when the blood sugar levels are high for long periods of time. It can also result from inadequate water intake, or excessive sweating, vomiting or diarrhea.

• No one adapts to dehydration

Dehydration• 1% of fluid loss= Elevated Core

Temperature– Treatment involves rest in a cool shaded area

and drinking mildy salted fluid. • 3-5% of Fluid Loss= Heat Exhaustion

– The Cardiovascular system is unable to pump sufficient blood to meet all of the body’s needs and inability to dissipate heat.

• At 7% loss= Heat Stroke– Profuse sweating, rubbery legs, chills, slight

confusion, nausea, vomitting, rapid and weak pulse, collapse likely

Signs of Dehydration• Thirst

• Irritability

• Fatigue

• General discomfort

• Headache

• Weakness

• Dizziness

•Muscle cramps

•Chills

•Vomiting/nausea

•Head or neck heat sensations

•Decreased performance

Types of Fluid• The ideal beverage may not be plain

water

• Beverage should replace sweat lost during physical activity and contain:– Water for hydration

– Carbohydrate to speed absorption of fluid and begin refueling muscles

– Electrolytes to speed rehydration

When Sports Drinks are Better Than Water

• During intense exercise

• During exercise that lasts longer

than 45-50 minutes

• During training that occurs multiple

times throughout the day

• When regular meals are not available

• Anytime a sport or activity is competitive

Casa, DJ, et al. NATA Position Statement: Fluid Replacement For Athletes. Journal of Athletic Training. 2000;35(2):212-224.

Benefits of Sports Drinks• Sodium

– May increase water retention (less urine)– Sodium activates thirst mechanism

( voluntary rehydration)– Decrease risk of hyponatremia– Decrease risk of muscle cramps– Most importantly, it replaces sodium lost in

sweat and helps maintain fluid homeostasis

Casa, DJ, et al. NATA Position Statement: Fluid Replacement For Athletes. Journal of Athletic Training. 2000;35(2):212-224.

Fluids to Avoid During Exercise• Diuretics are drugs that help get rid of water and

salt and promote urination– Caffeinated beverages– Alcohol– Carbonated beverages (GI distress)– Herbal Caffeine Supplements– Guarana– Kola Nut– Herbal Diuretics– St. John’s Wort– Ephedra

How Do You Monitor Fluid Balance?

• Go Pee!• Each pound (0.45 kg) lost during

activity represents 1 pint (16 ounces or 2 cups) of fluid loss• Signs of dehydration include the

following:–Dark yellow, strong-smelling urine–Decreased frequency of urination–Rapid resting heart rate–Prolonged muscle soreness

Fluid and Electrolytes

• Electrolytes–The major electrolytes lost in sweat are

sodium chloride, and, to a lesser extent, potassium

• Fluid Replacement–The ultimate goal is to start exercise in a

hydrated state, avoid dehydration during exercise, and rehydrate before the next training session

Key Point

• Consuming adequate fluids before, during, and after training and competition is essential to optimal resistance trainingand aerobic endurance exercise

Fluid Replacement Guidelines• Before a Training Session

–Encourage athletes/clients to hydrate properly before prolonged exercise in a hot environment.

–Intake should be approximately 16 fluid ounces (2 cups) of a cool beverage 2 hours before a workout

Fluid Replacement Guidelines• During a Training Session

– Provide cool beverages (about 50-70 °F [10-21 °C]).

– Have fluids readily available, since the thirst mechanism does not function adequately when large volumes of water are lost

– Athletes need to be reminded to drink

– Athletes should drink fluid frequently—for example, 6 to 8 fluid ounces (about a cup) every 15 minutes

Fluid Replacement Guidelines• After a Training Session

– Athletes should replenish fluids with at least 1 pint (16 oz or 2 cups) of fluid for every pound (0.45 kg) of body weight lost

– Weight should be regained before the next workout

– Water is an ideal fluid replacement, although flavored beverages may be more effective at promoting drinking

– The ideal fluid replacement beverage depends on the duration and intensity of exercise, environmental temperature, and the athlete

Fluid Replacement Guideline Summary

1 cup © = 8 fluid oz (fl oz)

1 pint (pt) = 2 cups = 16 fluid oz

1 liter (L) = 2 pints = 4 cups = 32 fl oz

• 2 hours before a workout: 16 fl oz.

• During exercise: 6-8 fl oz. every 15 minutes

• After exercise: 1 pt (.5 L) for every pound (.45 kg) of body weight lost

Heat Index• The heat index is an accurate measure of how

hot it feels (in degrees) when moisture (relative humidity) is added to the actual air pressure

• On this scale, high humidity can make you excruciatingly hot because your body has no way to eliminate excess heat.

• For example, 100 degrees F with 100-percent humidity is the equivalent of 195 degrees F at 25-percent humidity -- nearly the boiling point of water!

Heat Index• Dehydration, heat exhaustion and heat stroke can

occur faster if you perform outdoor activities• Evaporative cooling works great if the air is dry. In

high humidity, however, it doesn't work very well. The sweat cannot evaporate because the air is already saturated with humidity.

• In high temperature/high humidity environments, your body can get into a dangerous situation where it cannot radiate or evaporate the heat away.

• The heat index that you see on the evening news is designed to make you are aware of these dangerous situations

Heat Illnesses

• Heat Cramps

• Heat Exhaustion

• Heat Stroke

• Hyponatremia

Heat Related Muscle Cramps

• Symptoms– Muscle spasms (Calf, Hamstrings, Abdomen)

– Occasionally Whole Body Cramps

– Muscle pain

Athletes Prone To Getting Heat Cramps

• History of heat cramps

• Eats a low-salt diet

• Sweats early and heavy

• Poor hydration habits

• Excessive sodium losses through sweat

• Not acclimated to heat/humidity

Treating Muscle Cramps

• Mild Stretching

• Ice Massage

• Rest

• Fluid replacement

• Additional sodium

Heat Exhaustion

• Heat Exhaustion: 3-5% of Fluid Loss

• The Cardiovascular system is unable to pump sufficient blood to meet all of the body’s needs

Heat Exhaustion• Signs and

Symptoms: profuse sweating, rubbery legs, chills, slight confusion, nausea, vomiting, rapid and weak pulse, excessive fatigue, pale or flushed skin, impaired ability to dissipate heat

Heat Exhaustion• Treatment: Rest in

a cool environment, elevation of legs, pouring of cool water on the skin, replacement of fluids orally or IV. Recovery within 12-48 hours

Heat Stroke• Heatstroke is 7% loss

of fluid• Failure of the

cardiovascular system during exercise in a hot environment

• Extreme hyperthermia: core body temp above 104 Farenheit

• Medical Emergency

Heat Stroke• Symptoms

– Weakness – Irrational behavior– Drowsiness– Confusion– Disorientation– Dizziness– Nausea– Rectal temperature >104 F – Hypotension (systolic <90 mm Hg)– Hot Dry skin– Collapse

Emergency Management of Heat Stroke

• Seek medical attention immediately!

• Cool the body down before moving an athlete using:

• An ice bath (preferred)• Ice packs placed at

the groin, neck and armpits

• A cool shower• Wet towels• Water spray

Heat Illness Video

• http://www.youtube.com/watch?v=ESauS61OHFg&feature=related

High Profile Heat Related Deaths• Korey Stringer

–Minnesota Vikings

–27 years old

–335 pounds

–Collapsed of heatstroke during fall camp; died 15 hours later

High Profile Heat Related Deaths

• Eraste Autin– University of Florida

freshman fullback

– 6’2”, 250 pounds

– 88 degrees, 72% humidity on the day he collapsed during a routine training session

– Core temp > 108 degrees

Hyponatremia • Excessive sweating plus ingesting large

volumes of plain water during prolonged exercise sets the stage for hyponatremia (water intoxication) caused by a decrease in extracellular sodium concentration.

• Drinking too much water results In Low blood sodium (<135 mEq/L)

Hyponatremia

• Symptoms

–Early: Headache, apathy, fatigue, nausea and possibly cramping

–Advanced: Confusion, lack of coordination, seizure, coma, collapse and death

Hyponatremia• Prevention

–Eat salty foods and snacks–Drink fluids containing electrolytes–Avoid drinking only water

Treatment–Seek medical attention immediately!

Glucose, Electrolytes, and Water Uptake

• Large fluid intake may inhibit carbohydrate uptake

• Concentrated sugar solutions may impair fluid replacement

• Carbohydrate-containing solutions consumed during exercise enhance endurance performance by maintaining blood sugar concentration

Glucose, Electrolytes, and Water Uptake

• Glucose supplied in the blood can spare existing glycogen in active muscles

• The ideal hydration solution contains between 4-8% carbohydrates

• Adding moderate amounts of sodium to the ingested fluid helps to maintain plasma sodium concentration