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Scientific Inquiry Tied to Genetics,

Evolution, and Obesity

T-Talk 4.1 By Jennifer Turley and Joan Thompson

© 2013 Cengage

•  The field of nutritional sciences •  The process of science •  The scientific method •  Research/study designs •  How dietary recommendations

are made •  Epidemiological study results

reveal an obesity epidemic.

Presentation Overview

Scientific Inquiry

•  The field of nutrition is based on scientific study that integrates biology, physiology, microbiology, botany, chemistry, genetics and molecular biology.

•  In order to understand how evidence is produced, it is crucial to understand the basics of scientific inquiry.

The Scientific Method •  Is hypothesis driven •  Follows a basic format

– Ask a question (define the problem) – Form a hypothesis – Design an experiment – Collect, analyze & interpret the data – Generalize & publish the findings – Ask another question (the findings

generally leads to more questions)

Design the study to test the hypothesis

The Scientific Method

A validated hypothesis may lead to a theory such as the theory of evolution or the thrifty gene theory

Examples of Theories in Science and Nutrition

Theory Scientific Explanation Cell The cell is the most basic unit of life, organisms are made of one or more cells, and new

cells arise from existing cells. Years ago it was hypothesized that humans are born with a certain number of fat cells. Now it is known that fat cells can divide when they have been filled to capacity.

Evolution The change in heritable genetic composition of a population, such as by gene mutation and as a result of natural selection. There are several theories about how life forms began on earth; the well accepted theory of evolution is one of them.

Set Point There seems to be a range of body weight that is relatively easy to maintain and is genetically and physiologically controlled. The lower body weight range is more tightly defended to prevent starvation and preserve life. There are many feedback mechanisms that influence intake and satiety.

Thrifty gene Humans who efficiently stored food energy as body fat survived tough times during the hunter-gatherer period of human existence. Natural selection of these thrifty genetic traits through evolution may lead to present day obesity when the person lives in a toxic food environment and leads a sedentary lifestyle. There are many factors involved in survival; energy storage ability is one of them.

Glucostatic Blood glucose levels affect overall bodyweight; mild hypoglycemia is associated with elevated levels of insulin which inhibits the satiety center and promotes positive energy balance. Normal glycemia results in satiety and better weight control. There are many factors involved in bodyweight control; glycemia is one of them.

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•  Case studies •  Clinical studies •  Intervention trials •  Epidemiology •  Laboratory experiments

Research Designs Study Types •  Case: Results from a single person

protocol conducted by a medical doctor. •  Clinical: Experimental design with a

group of people. •  Epidemiological & Intervention:

Population based, retrospective or prospective.

•  Laboratory: Experimental design with any life form; microorganisms, virus, animals, plants, cell lines, bugs, etc.

Experimental Design things to consider

1. Number of Subjects: is there enough for statistical significance.

2. Duration of the Study: is it long enough for conclusions to be made.

3. Matching Groups: Ethnicity, gender, age, lifestyle, disease.

4. Control Groups: experimental vs placebo.

5. Reproducible Results: can the experiment be repeated and yield the same results.

6. The Treatment Protocol: blind, double blind, crossover.

Treatment Protocol •  Blind: the subject does not know if they

are in the experimental or control group. •  Double Blind: the subject and the

primary investigator do not know who is in the experimental or control group.

•  Cross over: each group experiences a period of being on the placebo and experimental drug.

•  A highly reputable study design is called the double-blind cross over experiment.

•  Consistent results from multiple credible studies published over many years are used to make dietary recommendations.

•  A whole body of evidence, collected over many years of experimentation is interpreted by the scientific community to create public recommendations regarding diet and health (disease prevention).

Public Recommends

Epidemiological study results reveal an obesity

epidemic

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Obesity: An Epidemic

•  Obesity is body fatness significantly in excess of the level that is consistent with optimal health.

•  There has been an uncontrolled rise in obesity in the United States over the last 20 years.

•  Obesity is defined by Body Mass Index (BMI).

BMI RISK <18.5 18.5-24.9 25-29.9 30-34.9 35-39.9 ≥40

Underweight Normal Overweight Obesity (class I) Obesity (class II) Extreme Obesity

BMI BMI= wt(kg)÷[ht(m)]2

BMI 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

Ht Wt (lbs)

60 97 102 107 112 118 123 128 133 138 143 148 153 158 163 168 174 179

61 100 106 111 116 122 127 132 137 143 148 153 158 164 169 174 180 185

62 104 109 115 120 126 131 136 142 147 153 158 164 169 175 180 186 191

63 107 113 118 124 130 135 141 146 152 158 163 169 175 180 186 191 197

64 110 116 122 128 134 140 145 151 157 163 169 174 180 186 192 197 204

65 114 120 126 132 138 144 150 156 162 168 174 180 186 192 198 204 210

66 118 124 130 136 142 148 155 161 167 173 179 186 192 198 204 210 216

67 121 127 134 140 146 153 159 166 172 178 185 191 198 204 211 217 223

68 125 131 138 144 151 158 164 171 177 184 190 197 203 210 216 223 230

69 128 135 142 149 155 162 169 176 182 189 196 203 209 216 223 230 236

70 132 139 146 153 160 167 174 181 188 195 202 209 216 222 229 236 243

71 136 143 150 157 165 172 179 186 193 200 208 215 222 229 236 243 250

72 140 147 154 162 169 177 184 191 199 206 213 221 228 235 242 250 258

73 144 151 159 166 174 182 189 197 204 212 219 227 235 242 250 257 265

74 148 155 163 171 179 186 194 202 210 218 225 233 241 249 256 264 272

75 152 160 168 176 184 192 200 208 216 224 232 240 248 256 264 272 279

1991

(*BMI ≥30, or about 30 lbs overweight for 5’4” person)

Obesity Trends* Among U.S. Adults BRFSS, 1991, 1999, 2008, and 2010

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1999

2008

No Data <10% 10%–14% 15%–19% 20%–24% 25%–29% ≥30%

2010

Why is Obesity of Concern?

Increased risk for chronic diseases

Type 2 diabetes •  Type 2 diabetes is becoming

more prevalent in obese adults & children.

•  Obese children are more likely to become obese adults.

•  The onset of Type 2 diabetes is preventable by diet, exercise & a good weight control program.


Increased risk for chronic diseases

•  Type 2 diabetes •  Heart disease & Cancer •  Liver/gallbladder disease •  Arthritis •  High-risk pregnancy •  Hernia & Varicose veins •  Accidents •  Depression & Low self esteem


Increased risk for medical conditions

•  High blood pressure (hypertension)

•  High blood cholesterol and triglycerides

•  High blood sugar •  Overall obesity leads to

decreased longevity and decreased quality of life

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Summary •  Nutrition has relied upon scientific study to understand

the relationships between diet and disease. •  Data synthesis from multiple study types (laboratory,

case study, & epidemiology). •  Data synthesis across numerous disciplines

(physiology, anatomy, chemistry, immunology, virology, etc) over time.

•  With consistent results have helped answer questions pertaining to human health.

•  Epidemiological study results have verified the obesity epidemic.

•  Obesity increases the risk for many chronic diseases and medical conditions.

References for this presentation are the same as those for this topic found in module 4 of the textbook

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Energy Balance


© 2013 Cengage

Presentation Overview •  Energy Balance Equations •  States of Energy Balance •  Energy Intake verses Expenditure •  Components of Energy Expenditure

Principles of Energy Balance •  1 pound fat = 3500 Calories stored. •  To lose body fat, a Calorie deficit needs to

be created. •  To gain body weight, a Calorie excess

needs to be created.

Body weight changes are based on the relationship of Caloric (Energy) intake & Energy Expenditure.

Energy Balance Equations •  If Calories Consumed = Calories Expended

–  Body weight is typically maintained. Energy balance occurs.

•  If Calories Consumed > Calories Expended –  Weight is typically gained . Positive energy balance occurs.

•  If Calories Consumed < Calories Expended –  Weight is typically lost. Negative energy balance occurs.

Energy Intake

•  Consumption of Energy Producing Nutrients in Food and Beverages –  Protein (4 Calories per gram) –  Carbohydrate (4 Calories per gram) –  Fat (9 Calories per gram) –  Alcohol (7 Calories per gram)

•  All of the Calories add up!

Energy Expenditure •  Basal Metabolic Rate (BMR)

»  An amount of energy needed to sustain life

•  Voluntary muscle movement »  Calories burned in physical activity (PA)

•  The specific dynamic action (SDA) of food (also called the thermic effect of food)

»  Energy required for food digestion & processing

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Energy Expenditure

~60% BMR

Energy Expenditure

Basal Metabolic Rate (BMR): •  The energy required by the body to minimally

function (heart to beat, lungs to breathe, …). •  It is determined in a fasting state (12 hours)

and when the body is at complete rest. •  Majority of expenditure in a sedentary person.

Energy Expenditure Resting Energy Expenditure (REE): •  Is similar to BMR. •  It considers the amount of energy burned by

a person at rest. •  REE can be measured in the lab or

estimated using the Mifflin Equations.

The Mifflin Equations Are based on gender, height, weight, and age REE Formula For WOMEN: •  REE (Calories/day) = •  (10 x W) + (6.25 x H) – (5 x A) - 161 REE Formula For MEN: •  REE (Calories/day) = •  (10 x W) + (6.25 x H) – (5 x A) + 5

W= Weight in Kg (pounds divided by 2.2) H = Height in centimeters (inches x 2.54) A= Age in years

Factors Affecting BMR/REE •  Age: BMR is reduced with age. •  Gender: More lean mass means a higher BMR

(gender differences). •  Physiological State: Illness, pregnancy, lactation,

stress, metabolic diseases like hyperthyroidism can increase the BMR. Starvation or prolonged fasting decreases BMR up to 80% in women & 60% in men.

•  Environmental Temperature: Hot or cold temperatures increase BMR.

Energy Expenditure Physical Activity (PA): •  The energy expended to perform

physical activity. •  Voluntary muscle movement. •  The total amount of energy

expended increases with body weight and the intensity of the exercise.

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Physical Activity & Calorie Burn •  The BMR or REE can be used to determine

energy spent or Calorie burn in PA. •  Calories burned = Hours spent in activity x

REE x Activity Factor ÷ 24 hours/day. •  Activity factors

•  Sleeping/Reclining: Factor of 1 •  Very Light Activity: sitting or standing in a small space:

Factor of 1.5 •  Light Activity: moving without sweating: Factor of 2.5 •  Moderate Activity: moving and sweating: Factor of 5.0 •  Strenuous Activity: all out efforts that cannot be sustained for

more than a few minutes without exhaustion: Factor of 7.0

Energy Expenditure Specific Dynamic Action (SDA): •  The food processing charge. •  Also called the thermic effect of food. •  ~10% of the total number of Calories

consumed is required for the digestion, absorption & assimilation of nutrients into the body.

•  Metabolism is increased when fed.

Summary •  Energy balance is the state of energy intake

verse energy expenditure. •  Intake occurs with food consumption. •  Expenditure occurs by BMR, PA, & SDA.

Weight gain & body fat accumulation occurs with positive energy balance. Weight loss & fat mass reduction occurs with negative energy balance.


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Body Composition and Weight Control


© 2013 Cengage


•  Body Composition •  Body Weight verses Body Fat •  Fat Distribution •  Combating Obesity (Effective

Weight Loss) •  Diet Planning for Nutrient Adequacy

Body Composition •  Determination of body weight should be

based upon body composition. •  It is important to know the % of total

body weight that is fat. •  Values should be considered for

maintaining good health, personal appearance, & performance reasons.

Healthy Body Composition •  Lean body mass ~55% of total body

weight (muscle is ~70% H20) •  Essential fat mass

–  3% body fat in 12% body fat in •  Stored fat mass is variable ~ 15-20%

(Additional fat beyond essential fat is stored) •  Minerals ~4% of total body weight •  Water ~ 60% of total body weight

Body Weight vs. Body Fat The best way to determine obesity is to

determine the % of body fat.

§  is too fat if ≥20% body fat.

§  is too fat if ≥26% body fat.

Interpreting Body Fat Body Fat

Categories % Body Fat

MALE % Body Fat

FEMALE

Essential Fat 3 12 Very Lean! ≤10 ≤13 Lean 11–15 14–19 Physically Fit** 12–15 18–22 Not Fat (Average) 16–19 20–25!Fat* 20–27 26–32 Obese > 28 > 33 *Strong recommendations for fat cell reduction are made when males exceed 20% body fat, and females exceed 26% body fat. **If you are male and less than 12% or a female and less than 18% body fat, you may interpret the result as being physically fit.

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Determining Body Fat •  Underwater weighing (very accurate) •  Bod Pod (very accurate) •  Skin fold calipers (the more sights,

the better) •  Bioelectrical impedance (the persons

hydration level affects the reading accuracy)

•  Futrex 5000 (more accurate when average body fat)

•  Research Techniques (DEXA, MRI, total body potassium, substance dilution)

Under Water Weighing

Bod Pod Skin Fold Calipers

Electrical Impedance

Fat Distribution Gut vs. Butt

•  Central adiposity (obesity) has increased health risks: – Type 2 diabetes – Hypertension – High blood

cholesterol – Dyslipidemia – Heart disease

Central Adiposity Android Obesity & Apple Shape

Determined by waist measurement.

§  waist measurement > 40 inches = central adiposity & apple shape.

§ waist measurement > 35 inches = central adiposity & apple shape.

Gynoid Obesity Pear Shape

•  Pear shape is determined by a large hip measurement.

•  Subcutaneous fat accumulates around the hips.

•  Is not as detrimental to health as visceral fat accumulation in the abdominal cavity.

Body Mass Index (BMI)

•  Indicates the healthiness of body weight in relation to height.

•  Is not an accurate measure of % body fat.

•  A BMI ≥ 25 and a waist circumference of >40 inches for men or >35 inches for women places an individual at increased risk for: –  Heart disease, Hypertension,

Dyslipidemia, & Type 2 diabetes.

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Calculating BMI

BMI = Weight (Kg) Height (M)2

Conversions:

Kg = Pounds ÷ 2.2 M = Inches ÷ 39.37

Do not forget to square the height in meters or

your math will falsely indicate obesity!

Sample Calculation John weighs 182 pounds and is 68 inches tall, What is his BMI?

•  182lb ÷ 2.2 = 82.73Kg •  68 inches ÷ 39.37 = 1.73 Meters •  1.732 meters = 2.99 Meters squared •  (M2 could also be calculated as 1.73 x

1.73 = 2.99 Meters squared)

John’s BMI = 82.73 Kg = 27.7 2.99 M2

People with high LBM may have a high BMI but are not obese. It is a good idea to determine body composition on all individuals who have a BMI that is ≥25 to confirm obesity.

Interpreting BMI

BMI Risk <18.5 Underweight 18.5-24.9 Normal 25-29.9 Overweight 30-34.9 Class I Obesity 35-39.9 Class II Obesity ≥40 Extreme Obesity

Combating Obesity

Surgery: •  Lipo-suction •  Intestinal

resection •  Gastric bypass •  Gastric band Drugs: •  Over the counter

& prescribed

Combating Obesity Diets: Low carb &/or very low Calorie •  There is 6% success rate for reducing

weight and maintaining the weight loss by dieting.

•  During prolonged fasting (or low calorie, low carb diets), the BMR declines and lean body mass is used to make glucose for brain, central nervous system, and red blood cell functioning.

•  The body chemistry changes under conditions of Feasting & Fasting

Feasting

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Short Fasting Long Fasting

Weight Control •  When considering weight loss, it

is important to lose the excess fat weight and preserve the lean body mass or muscle.

•  The reason for weight loss should be to decrease excess of body fat.

•  Fat weight loss is a slow process.

Effective Weight Loss

•  Optimal weight loss rate is 1 lb/week.

•  1 lb of fat weight loss requires a 3500 Calorie deficit.

•  A 500 Calorie deficit per day times 7 days per week produces a rate of weight loss of 1 lb/week.

500 Calorie Deficit/Day •  40 minutes aerobic exercise = 300 Calories

(preserves LBM, BMR and utilizes stored fat) •  22g of dietary fat removed from the diet =

200 Calories. •  Results in:

–  1 pound per week of body fat lost. –  Preservation of lean body mass.

•  A faster rate of weight loss forces the body to use muscle protein to meet the glucose/energy needs of the body.

Benefits of Exercise It promotes •  Cardiovascular fitness •  Higher HDL levels •  Lower resting heart rate •  Lower blood pressure •  More LBM •  Flexibility, strength &

endurance •  Healthy body weight •  Better mental outlook

Burning 2000-3000 Calories per week reduces disease

Over exercising one area of the body does not result in spot reduction

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Making the Changes •  Incorporating the dietary changes

and the exercise behaviors permanently into the lifestyle requires a step process.

•  A progressive behavior modification program can facilitate successful lifestyle changes.

Behavior Modification •  Identify goal (realistic). •  Identify current behaviors that need to

change. •  Identify behaviors that will achieve the goal &

reinforce them. •  Commit to change. •  Plan (set realistic small behavior changes

into action, rewards). •  Persist long enough to see results, reinforces

motivation. •  Evaluate the progress & modify the plan

Life Long Diet Protocols Greater long term success rates with: 1.  Eating a well balanced diet from a

variety of foods to achieve nutrient adequacy.

2.  Incorporating an hour-long exercise program daily.

3.  Using behavior modification to permanently incorporate desired health behaviors

What is Nutritional Adequacy?

The diet provides: •  Essential nutrients •  Fiber •  Energy to maintain health.

When should it be considered?

•  Nutritional adequacy should be considered for each individual diet.

•  In weight loss, weight maintenance or gain diets, nutritional adequacy should also be considered.

How is it measured?

Dietary assessment tools like: •  Diet Analysis software programs •  Food Composition tables & databases •  The MyPyramid model &/or •  The Exchange System

Used to prescribe & monitor dietary intake.

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How is it interpreted? •  All diets (especially weight control

diets) need to be planned so that there are no nutritional inadequacies, deficiencies, or risks for toxicity. –  Inadequate Intake: < 100% of the DRI – Deficient Intake: < 66% of the DRI – Risk of Toxicity: > 100% of the UL

What other factors should be considered?

The diet should be planned to promote health by limiting:

•  Saturated & trans fatty acids, cholesterol, simple sugar, & Sodium.

•  Plan intake of Calories from carbs, protein, and fat to meet AMDR.

Summary •  Individuals need to know their

body composition (LBM vs. Fat Mass).

•  There are different methods to determine body composition.

•  The distribution of body fat affects health (visceral verses subcutaneous fat).

Summary •  BMI is a recommended measure

for determining appropriate body weight for height.

•  A slow rate of weight loss is suggested to preserve lean body mass while reducing fat mass.

•  Lifelong diet and exercise habits should be practiced for optimal body weight, health, and nutrient adequacy.


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Principles of Fitness for Health


© 2013 Cengage


•  Total Fitness For Health •  Fitness Testing •  Aerobic and Resistive Exercise •  The Overload Principle •  Logging Activity for Weight Control and

Health

Total Fitness for Health

•  “Fitness is health!” •  It has been document that individuals

who are physical fit have far less mortality and morbidity as compared to their sedentary counterparts.

•  What does being physically fit mean? •  What are the health benefits of

exercise?

The Values of Exercise Exercise Value Specific areas of benefit General Health Improved mental health

Increased feeling of vigor Improved sleep pattern Increased bone density Decreased risk of chronic diseases such as cancer, heart disease, diabetes, arthritis, and vascular diseases

Body Composition and Weight Control

Decreased percent body fat Increased lean body mass Stabilized body weight Increased metabolic rate Improved muscle tone

Cardio-Respiratory Health and Fitness

Improved circulation (pumping capacity of the heart, stroke volume, oxygen delivery capacity to the tissues, and promotion of wound healing, decreased tendency for infections) Increased oxygen uptake Improved lipid profile, decreased total cholesterol (increased HDL, decreased LDL), decreased triglycerides Decreased blood pressure Decreased heart rate Increased efficiency of metabolic processes (fat metabolism and carbohydrate metabolism)

Athletic Performance Improve competitiveness in sporting events Body Sculpting

Fitness Testing

•  The accumulated score from the elements of evaluating: – Aerobic capacity – Muscular strength – Muscular endurance – Flexibility – Body composition

•  A high overall score is associated with health and longevity

Developing a Total Fitness Program

•  A safe and effective fitness program to perform well in Physical Fitness testing and reduce the risk of injury includes a: – Warm-up – Aerobic exercise – Resistive exercise – Flexibility exercise – Cool-down

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Aerobic & Resistive Exercise •  Aerobic exercise demands a higher

functioning level of the cardio-respiratory systems – The capacity is reflected by VO2max

•  Resistive exercise demands a higher functioning level of the skeletal-muscular systems – The capacities are displayed through

measures of muscular strength and muscular endurance

Aerobic Exercise •  Physical activity where the heart rate can

be elevated and maintained steadily for at least ten minutes and there is increased oxygen uptake and delivery to the body and muscles

•  A few examples include walking, jogging, cycling, swimming, and cross country skiing

•  The three parameters that affect aerobic capacity are frequency, intensity and duration of the exercise

Heart rate, exercise intensity, and physiological responses The FIT Classification System

•  You can use: – F-frequency (times per week) –  I- intensity (percent of maximum heart

rate, %MHR) – T-time (the number of minutes that the

elevated heart rate is maintained •  To classify your level of cardiovascular

competency by the following table:

The FIT Classification System

Factor Low Average High F - frequency (days/wk)

3 4 5 +

I - intensity (%MHR)

60 – 69 (low)

70 – 79 (moderat

e)

80-90 (high)

T - time (continuous minutes)

10 - 20 15-45 30-60

Resistive Exercise •  One can improve muscular strength or muscular

endurance by determining first, the one-repetition maximum and then adjusting the amount of: –  Resistance (the amount of opposing weight during the

muscle contraction, strength train at 80% of the one-rep-max)

–  The number of repetitions of the muscular contraction and the number of sets completed

–  Speed of the muscle contraction

•  3-4 sets of 8-12 reps twice a week to maintain strength and three times a week to gain strength.

•  There are many ways to contract a muscle and affect muscle strength

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Muscle Contractions, Training Types, and Balanced Lifts

Muscle Contractions Training Types Balance Lifts Eccentric Muscle Contraction Muscle is elongating while contracting or generating tension Concentric Muscle Contraction Muscle is shortening while contracting or generating tension Isometric Muscle Contraction Static muscle length while muscle generates tension. This type of contraction is uses when joints are injured to attempt to maintain some muscle strength.

Isometric Training Program involves a series of isometric muscle contractions. Isokinetic Training The use of special equipment to control the speed of the muscle contractions. Circuit Training Combines aerobic activity with resistive activity for the purposes of increasing calorie burn, reducing boredom and improving fitness. Weight Training Program involves lifting weights.

Bench press/seated row Dumbbell bench press/ bent-over row Shoulder press/lateral pulls Seated leg press/truck flex Pectoral fly/bent-over fly Upright row/dips Lateral raises/medial pulls Leg extension/leg curls Bicep curl/tricep extension

The Overload Principle •  The Overload Principle involves applying

a greater work load than normal on the cardio-respiratory or skeletal-muscular systems that leads to increased functional capacity

•  For aerobic capacity improvement, one must work at least at 70%MHR

•  For muscular strength, one must lift at least at 80% of the 1-rep-max (3 sets of 8-12 reps)

Logging Activity for Weight Control and Health

•  An exercise volume that has been associated with reducing the risk of chronic disease is burning between 2,000-3,000 Calories per week in exercise

•  30-45 minutes of moderate intensity exercise, 3-5 times per week promotes weight loss.

•  60 minutes of rigorous activity per day is needed to lose weight, keep the weight off, and improve functional capacity.

Logging Activity for Health •  You can use the following activity log to

evaluate your exercise for; •  Total fitness format

– Warm-up – Aerobic exercise – Resistive exercise – Flexibility exercise – Cool-down

•  Calorie burn of activities – Time x factor x REE ÷ 24

Exercise Activity

Log

Summary •  The common dominator for exercise is

Calorie burn and a minimum amount of exercise to yield health benefits is burning between 2,000 and 3,000 Calories per week.

•  To lose weight, to keep the weight off, and to improve functional capacity 60 minutes of rigorous activity is needed daily.

•  The parameters evaluated in physical fitness testing include; body composition, flexibility, aerobic capacity, muscular strength, and muscular endurance.

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Summary •  A total fitness program can support a good

rating on physical fitness testing because it includes; a warm-up, cool-down, flexibility exercises, aerobic activities, and resistive muscular work.

•  The three parameters to increase for improving aerobic capacity are frequency, intensity and time.

•  The three parameters to increase for improving muscular strength are the amount of resistance, the number of reps and sets, and the speed of the muscle contractions.

References for this presenta/on are the same as those for this topic found in module 4 of the textbook

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Fundamentals of Exercise for Nutrition


© 2013 Cengage

Presentation Overview •  Fuel and Utilization During Exercise •  Carbohydrates

–  Carbohydrates in the Body and Diet –  Carbohydrate Management for Enhanced Exercise Performance –  Recovery Nutrition after Exercise

•  Proteins –  Proteins in the Body and Diet –  Protein Management for Enhanced Exercise Performance

•  Fats –  Fats in the Body and Diet –  Fat Management for Enhanced Exercise Performance

•  Thermal Regulation and Hydration –  Understanding and Controlling Body Temperature –  Dehydration to Hydration

Fuel Utilization During Exercise •  ATP production is primarily from carbohydrate and

fat •  As the intensity of the exercise increases, the

percent of carbohydrates used to produce ATP increases

•  Nutrition supplies the substrate or fuel (carbohydrate, fat and protein) and the essential structural components of enzymes (cofactors) needed to drive chemical reactions to generate ATP through: –  Glycolysis –  The citric acid cycle –  The electron transport chain.

ATP energy production through glycolysis, the citric acid cycle, and the electron transport chain

Carbohydrates

•  The objectives of dietary carbohydrate management is to maintain blood sugar and replete muscle glycogen

•  Carbohydrate as fuel supports high intensity exercise

•  Carbohydrate are limited in the body

Carbohydrates in the Body and Diet

•  Blood Glucose –  4.5 grams of glucose total – Constantly used by RBC and CNS

•  Liver Glycogen –  75 (to 100) grams when repleted – Used to maintain blood glucose

•  Muscle Glycogen – Amount of exercise and dietary

carbohydrate intake determines the amount – Used to produce ATP in the muscle during

exercise

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Carbohydrate Management for Enhanced Exercise Performance •  Diet and exercise influence glycogen stores in

the muscle. –  High carbohydrate intake (7-10 gm/Kg/day) –  60-65% of Calories from carbohydrate

•  The timing of the carbohydrate intake in relation to exercise is important: –  Prior to the Exercise (4 hours before or 2 hours

before and 5-10 minutes before) –  During the Exercise (about every 15 or 20

minutes) –  After the Exercise (immediately after and again

2-6 hours later)

The timing of carbohydrate intake for exhaustive athletic performance

Timing and Amount of Intake

68 Kg Exchange List Pattern 68 Kg Food and Beverage Options for Exchange List Patterns

4 hours prior 4 gm/kg 1.82 gm/lb

10 starch 5 fruit 3 other carbohydrate

2 cups pasta (90 g) 1 bagel (60 g) 1 cup juice (45 g) 1 cup fat-free frozen yogurt (45 g) 1 large banana (30 g) (270 g total)

2 hours prior 2 gm/kg 0.91 gm/lb

6 starch 3 fruit exchanges

1.33 cups pasta (60 g) 2 slices of bread (30 g) 1 cup juice (45 g) (135 g total)

5-10 minutes prior 0.5-1 gm/kg 0.23-0.45 gm/lb

2-4 other carbohydrate Exchanges

1-2 low-fat sport bars (2 ounce size) or the equivalent of 2-4 tablespoons of sugar (34-68 g total)

During 60 gm/hr

2-4 other carbohydrate exchanges/hour

A six percent glucose electrolyte replacement solution provides about 15 grams of carbohydrate per cup of fluid (1 tablespoon of sugar and ¼ teaspoon of salt per one cup water, drink 2-4 cups per hour)

Immediately after Carbs: 1.65 gm/kg or 0.75 gm/lb Protein: 0.55 gm/kg or 0.25 gm/lb

7 starches, 3 meats Or 2 milk, 2 fruit, 4 starches, 2 meats Or 1 milk, 2 fruit, 4 starches, 3 meat

2 cups low-fat milk (24 g carbs, 16 g protein) 2 cup ready-to-eat cereal (60 g carbs, 12 g protein) 4 tablespoons raisins (30 g carbs) 2 egg whites (14 g protein) (114 grams of carbohydrate and 42 grams of protein total)

2-6 hours after Carbs: 1.65 gm/kg or 0.75 gm/lb Protein: 0.55 gm/kg or 0.25 gm/lb

5 starches, 2.5 vegetables, 3 meats, 2 fruits or similar to immediately after meal

3 ounces chicken (21 g protein) 1 large baked potato (60 g carbs, 12 g protein) 1.25 cups cooked broccoli (12 g carbs, 5 g protein) 1 small roll (15 g carbs) 1 large pear (30 g carbs) (117 grams of carbohydrate and 38 grams of protein)

Recovery Nutrition after Exercise

•  Muscle glycogen repletion begins immediately after the exercise and prepares the energy stores for the next workout!

•  Consuming meals that provide the combination of carbohydrate and protein at a three gram to one gram ratio promotes muscle glycogen repletion

Proteins •  Athletes require more protein to stay in

nitrogen balance as compared to individuals who are meeting their DRI for physical activity

•  The range is 1.2 to 1.6 grams of protein per kilogram of body weight

•  To support lean body mass gains, a strenuous weight-lifting program, 1.6 grams of protein per kilogram of body weight and a positive energy balance of 200 Calories is needed

•  High quality or the complement equivalent is needed for 2/3 of the protein consumed

Fats •  The dietary fat recommendations made to the

athlete are the same that support health and meet the DRIs

•  Consume low-fat foods prior to exercise and a low-fat (20-25% of Calories) diet in general

•  Adding MUFAs may be the best choice of fats if weight gain is desired

•  MCT have been touted to be useful during exercise, but not proven, however, they are useful for malabsorption syndromes due to their direct absorption into the blood stream

Thermal Regulation and Hydration

•  The ability to keep the body cooled during exercise is key to exercise capacity and avoiding injury.

•  A lot of heat is generated in the body due to the inefficiencies of energy transfer to make ATP.

•  Sweating creates the evaporative cooling system employed during exercise to keep the core body temperature in a functional range.

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Understanding and Controlling Body Temperature

•  The core body temperature rises during exercise

•  If the core body temperature >104oF, exercise capacity diminishes and risk of thermal injury increases

•  Fluid, salt, and other components are lost in sweat during exercise – about a liter of fluid per hour of exercise, and 2.6 grams of salt per liter

•  Salt (NaCl) is 40% sodium, ½ t salt replaces the sodium lost in 1 hour of vigorous exercise

Dehydration to Hydration

•  The fluid lost in sweat comes from the blood stream

•  The plasma volume is the fluid reserve for sweat

•  This is why there is such large deterioration in aerobic exercise capacity due to dehydration

Dehydration to Hydration •  The sensation of thirst signifies 2%

dehydration, cardiovascular and aerobic function is reduced.

•  5% dehydration, serious thermal injury risk. •  The body can absorb 1 liter of fluid per hour. •  Replacing fluids (cool, dilute, small, and

frequent amounts) during strenuous exercise is important: –  1 cup at 41oF, every 10-15 minutes –  Drink without thirst to avoid dehydration

Hydration Happy and Dehydration Demise

Importance of hydration during exercise

Cardiovascular demise during dehydration

•  Optimize muscle strength •  Optimize aerobic capacity •  Prevention of thermal injury

which include dizziness, cramping, fainting, heat exhaustion and heat stroke

•  Pool of fluid to draw upon for sweat loss is the blood stream.

•  The cardiovascular system is affected dramatically by fluid losses.

•  Plasma volume decreases •  Osmolarity of the blood

increases •  Blood pressure goes down. •  Constriction of the blood

vessels •  Increase in heart rate •  Decrease in heart filling •  Decrease in cardiac output •  Decreased sweating •  Increase in core body

temperature

Summary •  Fuel and hydration management are so

influential on exercise capacity. •  As the intensity of the exercise increases, so

does the percent of carbohydrate used to produce ATP.

•  Carbohydrate stores in the body are limited. •  Dietary carbohydrate intake before, during,

and after exhaustive exercise can enhance exercise performance.

•  A combination of carbohydrate and protein (3:1 ratio) consumed after exercise can support muscle glycogen repletion.

Summary

•  The protein needs of most competitive athletes range between 1.2 to 1.6 grams of protein per kilogram of body weight per day.

•  A low fat diet that provides all of the essential fatty acids in adequate amounts can support most athletic endeavors.

•  Adequate hydration from fluid and salt intake is important for aerobic performance and avoiding thermal injury.

References for this presenta/on are the same as those for this topic found in module 4 of the textbook

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