Nutritional Recommendations for the Physically Active Person

Chapter 7 Part 1

The Optimal Diet Supplies required nutrients in adequate

amounts for:Tissue maintenance and repair Growth without excess energy intake

The Optimal Diet Proper nutrition helps:

• Improve athletic performance • Optimize programs of physical conditioning • Improve recovery from fatigue • Avoid injury

Energy Balance Equation Body mass remains constant

Caloric intake equals caloric expenditure. 3500 kCal approximately equals 1 lb of

stored body fat. Consume 3500 extra kCal, gain 1 poundExpend 3500 kCal, lose 1 pound

Energy Balance

Principles of Good Eating Variety

• Creates a diet with sufficient amounts of required nutrients.

Balance • Intake of nutrients from the major food

groups. Moderation

• Planning to maintain a balanced nutrient intake throughout the day.

My Pyramid www.mypyramid.gov Can be personalized

Based on age, sex, and level of daily exercise Figure is to emphasize at least 30

minutes of moderate to vigorous daily physical activity

Based on the 2005 Dietary Guidelines for Americans

My Pyramid

Dietary Guidelines for Americans Control caloric intake to manage body

weight. Consume a variety of foods.

• Within the basic food groups Increase daily intake of:

Fruits, vegetables, whole grains, and nonfat or low-fat milk and milk products.

Choose fats wisely for good health. • Limit saturated fats and trans fats.

Dietary Guidelines for Americans (cont.) Choose carbohydrates wisely for good

health. Choose and prepare foods with little salt. If you drink alcoholic beverages, do so in

moderation. Be physically active every day. Keep food safe to eat.

Serving Size Versus Portions The USDA defines a standard serving of

pasta as one-half cup. The FDA, which regulates food labels,

claims a standard serving is 1 cup. Typical restaurant pasta portion averages

about 3 cups.• Equal to 6 servings according to MyPyramid

Mediterranean and Vegetarian Diet Pyramids Mediterranean

• Emphasizes fruits, nuts, vegetables, legumes, all manner of unrefined grains, and protein derived from fish, beans, and chicken

• High monounsaturated fatty acid content Vegetarian

• Consists of foods from the plant kingdom

Protein Intake - Physically Active RDA = 0.8 g/kg of body mass

Is it enough? Eating a high-carbohydrate diet

Adequate to conserve muscle protein during intense training.

Protein Intake - Physically Active Those in endurance training

1.2 to 1.6 g/kg/day of high-quality protein Those who resistance train

1.0-1.6 g/kg of body mass.

Protein Metabolism Enter (AA pool)

• Dietary• Tissue breakdown• Nonessential – formed in body

Protein Metabolism Exit - (AA pool)

• Into gut• Into tissue structure• AA N2 lost in urine, sweat• Oxidized• Stored as CHO, fat

Protein Synthesis Protein synthesis

• Gene expression• Each gene directs synthesis of one protein• DNA is transribed to mRNA (messenger RNA)• mRNA takes the message out to the ribosome• tRNA (transfer RNA) is also required to make

the new molecule

Rodent muscle• 113% increase in muscle urea N2 content• 1 h running

Increased degradation of muscle protein • Kasperek & Snider, 1989

Significant muscle damage • Armstrong et al. 1983• Significant eccentric component

Protein Needs-Physical Exercise

Protein Needs-Physical Exercise Research questions

• Does increased protein intake reduce this damage?

• Does increased protein intake speed the repair processes?

Protein Needs-Physical Exercise Branched chain amino acids (BCAA)

• Predominantly oxidized during endurance exercise

• Related to availability of BCAA and inversely proportional to glycogen availability • Increased BCAA/glycogen at end of prolonged run

• Fasting state

Branched Chain Amino Acids Daily requirements

• Single bout of exercise• 2 h 55% VO2max• Oxidation rate equivalent to 90% daily

requirement

Endurance Exercise and Protein Metabolism

Energy requirement – 1 h 65-75%VO2max

kcal/h %fat %pro %CHO

Males 838 23 5 72

Protein Synthesis

High Protein Intake Concerns?

• Kidney failure• Rodents – 80% protein

• No problems• Absence of reports of kidney problems in weight

lifter/body builders• High protein diets 20-30 years

• Excess N2 not a problem – In healthy individuals

High Protein Intake Concerns?

• Dehydration• Excess water loss with nitrogen excretion• Sweat loss• Proper rehydration – monitor body weight