Exercise Science: Nutrition and Body Comp

What should we limit according to dietary guidelines for Americans?

Saturated and trans fats, cholesterol, added sugars, salt, and alcohol

How can we maintain body weight in a healthy range?

-balance calories from foods and beverages with calories expended

-engage in regular physical activity and reduce sedentary activities

What percent of carbs should we be consuming?

45-65%

What percent of fat should we be consuming?

20-35%

What percent of protein should we be consuming?

10-35%

What are sugar and starches major energy sources for?

-Fuels red blood cells and neurons

-Critical to help spare protein tissue structures

What are the 2 types of dietary fiber?

Insoluble and soluble

Is dietary fiber a non-digestible carbohydrate?

Yes

What is soluble fiber linked to?

Lower serum cholesterol

What are the recommendations with dietary fiber?

38 g/day for men and 25 g/day for women. You want to increase dietary fiber and complex carb intake along with water

What are the different types of fat?

-triglycerides, phospholipids, cholesterol

-saturated

-monounsaturated

-polyunsaturated (omega 3 and 6)

What is the energy of fat?

9 kcals/g

What are some dietary recommendations for fat intake?

-consume 7-10% calories from saturated fats

-limit cholesterol to < 300 mg/day

-athletes should only eat 20-25% (unsaturated)

-limit intake of fat and oils high in saturated and trans fatty acids

Is protein a major source for exercise?

No it only yields 4 kcals/g

Do high-quality proteins contain the 9 essential amino acids?

Yes but they cannot be synthesized by the body

What are the protein intake requirements?

.8 g/kg body weight where athletes need 1.2-1.7 g/kg body weight. No more than 2.0 g/kg

How much body water loss affects performance?

Loss of 1-2%

What is the normal water loss per day?

2500 ml (2.5 L) but can increase to 6-7 L of loss due to temp and exercise

Where does water intake come from?

Beverages, solid foods and metabolic processes (2.7 L W and 3.7 L M)

What are the fat-soluble vitamins?

-A, D, E, K

-Can be stored in body

-Excess intake is toxic

What are the water-soluble vitamins?

-B vitamins: Thiamin (B-1), riboflavin (B-2), niacin, pyridoxine (B-6), folic acid, B-12, pantothenic acid, and biotin. For energy metabolism

-Vitamin C: maintenance of bone, cartilage, and connective tissue

What are the 4 key minerals?

Calcium, Iron, Sodium and Potassium

What is calcium?

Important mineral in teeth and bone structure. Deficiency leads to osteoporosis

What is iron?

An important mineral that is a component of hemoglobin where a deficiency leads to anemia

What is sodium?

A mineral associated with hypertension, especially in sodium sensitive individuals

What is potassium?

Mineral for fluid balance, electrolytes, muscles and heart contraction

What is athletic malnutrition caused by?

-inadequate fuel and fluid intake

-poor timing of refueling

What does athletic malnutrition result in?

Excessive reliance on supplements and ergogenic acids. Failure to adequately make up the difference of inadequate fuel and fluid

Should the dynamics of energy and fluid intake match the dynamics of usage?

Yes; maintain lean body mass, reduce body fat, improved well-being and performance

Should we have proportionally balanced carb, protein and fat intake?

Yes; high carbs (55-70%), moderate protein (15-20%) and low fat (20-25%)

Why is energy balance important for maintaining lean tissue?

Because we want to avoid feast and famine cycles and hyperinsulinemia

How should athletes prepare for competition?

-become rested

-build glycogen stores

-become well hydrated

How should athletes taper and carbo-load 10-7 days prior to event?

Carbs should be 55-60% of total calories

How should athletes taper and carbo-load 3-4 days prior to event?

-carbs should be 65-70% of total cal

-reduce fat and fiber, drink plenty of water

-focus on starchy veggies and grains

How many times a day should we be fueling ourselves?

3-6 meals, 3-4 hours apart

How can we make sure we are eating enough in the day?

-avoid skipping meals

-plan ahead to eat on the go

-practice your meals plan

-snack between meals

-divide meals around workouts

How often should we be drinking water during exercise?

Every 10-15 minutes during exercise

Is it important to allow enough time for food to digest before exercise?

Yes: large meals 3-4 hours, and small meals 2-3 hours

What are some optimal foods before exercise?

-1.0-4.5 g/kg of carbs 1-4 hours before

-consumption of protein and carbs

-high-fat, high fiber foods should be avoided before

-sports beverage 2-4 oz sipped every 10-15 minutes

-starchy snacks and water

What is a good pre-exercise/competition meal?

Wholesome carbs, balanced with protein and low fat and fiber

-pancakes with syrup, skim milk and banana

-cereal, skim milk, banana

What is a good pre-exercise/competition snack?

Easy to digest carbs, some protein, fluid

-fruit flavored yogurt and water

-saltines or animal crackers, low fat cheese and water

Why should we consume food during exercise?

-maintains blood glucose, and preserves liver glycogen

-maintains BCAA helping to prevent central fatigue and maintaining ration of serotonin and BCAA

-inhibits cortisol production which is catabolic to muscle tissue

How should we eat with intense exercise lasting greater than an hour?

-carb intake recommended at 10-20 minute interval

-4-8 oz of 4-7% carbs solution 30-60 g of carbs should be consumed per hour

What are some optimal foods during exercise?

-sports drinks, bars, gels, and glucose beans

-avoid fructose as it causes GI stress

-consuming carbs and protein improves net protein balance

What is basal metabolic rate (BMR)?

The rate of energy expenditure under standardized conditions (supine position, immediately after waking, 12-18 hours following a meal)

Does BMR represent 60-75% total energy expenditure?

Yes; lower in women and declines with age and is related to fat-free mass

What is the thermic effect of feeding?

-increased energy expenditure following ingestion of meals

-small part of total energy expenditure

-not predictive of obesity

What does brown adipose tissue do with thermogenesis?

It increases heat production in response to NE and thyroid hormones

What are some energy wasteful systems or futile cycles?

Metabolic cycles (sodium potassium pump)

How much total energy expenditure does physical activity and exercise count for?

5-40% but depends on activity level

Is physical activity and exercise important in determining obesity?

Yes; inverse relationship between physical activity and percent fat. Individuals more than 10,000 steps per day are in normal bmi range

How can we evaluate a healthy body mass (BMI)?

Hamwi method:

Males 106 lbs (5ft) + 6 lbs per inch

Females 100 lbs (5 ft) + 5 lbs per inch

What is the BMI classification for adults?

-underweight: BMI < 18.5 kg.m2

-normal: BMI 18.5-24.9 kg/m2

-overweight: BMI 25.0-29.9 kg.m2

-obesity: BMI >30.0 kg.m2

What is the overweight or obese classification for children?

-overweight: BMI > 85th percentile for age and gender

-obese: BMI > 95th percentile for age and gender

What does body composition refer to?

Refers to the makeup of tissues of the body-often used in reference to % body fat

What is the recommended body fat composition for males?

-essential = 3-5%

-fitness = 5-15%

-health = 8-22%

-obesity = .25%

What is the recommended body fat composition for females?

-essential = 10-12%

-fitness = 16-28%

-health = 20-35%

-obesity = >38%

How do methods of measuring body composition differ?

Vary in terms of complexity, time requirement and expense. Also vary in the degree of inherent error involved.

What is the standard error of the estimate (SEE)?

A measure of variation between predicted value and the true value

What are the 5 methods used to evaluate body composition?

-underwater weighing

-air displacement plethysmography

-dual energy x-ray absorptiometry (DEXA)

-bioelectrical impedance analysis (BIA)

-sum of skinfolds

How do we use underwater weighing and air displacement plethysmography?

-Both methods measure body density to estimate % body fat

-body divided into fat-free and fat mass

What is fat mass density and fat-free density?

-fat mass density = 0.900

-fat-free mass density = 1.100

How to calculate % body fat?

% body fat = (495 / density) - 450

What is dual energy x-ray absorptiometry (DEXA)?

-2 x-ray beams determine whole body and regional estimates of lean tissue, bone density and fat

-SEE = 1.8%

-disadvantages are expensive and certified medical personnel must perform scan

What is bioelectrical impedance analysis (BIA)?

-estimates body composition; simple and fast

-small electrical current is applied to one extremity and voltage drop is measured at another extremity

-lean tissue has a low impedance

-fat tissue has high impedance

What does impedance value in BIA provide?

Provides us with an estimate of total body water from which both fat-free and fat mass can be calculated (SEE = 3.5-5%)

What is skin fold technique?

-estimates body composition

-prediction of body density from estimation of subcutaneous fat

-thickness of subcutaneous fat

-calculated during Siri equation and % body fat calculated from body density

-SEE = 3.5%

What are other methods of measuring body composition?

-radiography

-ultrasound

-nuclear magnetic resonance (NMR)

-total body electrical conductivity (TOBEC)

What is radiography?

Measurement of fat width in a limb

What is ultrasound?

Measures thickness of subcutaneous fat

What is NMR?

Volumes of specific tissues

What is TOBEC?

Electrical conductivity of lean and fat tissue

What are the 3 somatotypes?

Endomorphy, mesomorphy, and ectomorphy

What is endomorphy?

Relative predominance of soft roundness and large digestive viscera

What is mesomorphy?

Relative predominance of muscle, bone and connective tissue

What is ectomorphy?

Relative predominance of linearity and fragility

What are the genetic factors causing obesity?

-account for transmissible variance for fat mass and percent body fat

-affects components of energy expenditure; spontaneous physical activity, resting metabolic rate, thermic effect of foot, and relative rate of carb and fat oxidation

What are the 3 causes of obesity?

Genetic factors, cultural factors and lifestyle factors

What diseases are linked to obesity?

-hypertension

-type 2 diabetes

-CHD

-stroke

-gallbladder disease

-osteoarthritis

-sleep apnea and respiratory problems

-cancers

What is the set point theory?

Biological set point for body weight much like the set points for other physiological variables

What is the physiological set point model?

-biological signals provide input to hypothalamus (blood glucose, lipid stores)

-food intake is either increased or decreased to maintain body weight

What is cognitive set point model?

-cognitive signals about perception of body weight

-influences food intake to maintain body weight

What is static energy balance?

-increased intake of 250 kcals/day would lead to 14 pound weight gain over one year

-change of energy stores = energy intake - energy expenditure

What is dynamic energy balance?

-increase in energy intake results in increased body weight (gain of 3.5 pounds a year)

-rate of change of energy stores = rate of change of energy intake - rate of change of energy expenditure

Carbohydrate and protein nutrient balance

-excess intake is more easily oxidized compared to fat

-body regulates expenditure to match intake

-does not contribute to weight gain as much as fat

Fat nutrient balance

-excess intake is not oxidized

-fat expenditure depends on total energy expenditure

-contributes to fat gain