1 dnt 200 nutrition for health sciences fitness and nutrition

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DNT 200NUTRITION FOR HEALTH

SCIENCES

FITNESS AND NUTRITION

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I’d like to see tracks full of runners, pools full of swimmers, roads full of cyclists, trails full of hikers...

I’d like to see fewer cars on the road and more people walking...

I’d like to see my country once again become a nation of doers instead of spectators.

Kenneth H. Cooper, MD, MPH

Father of Aerobics

1968

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FITNESS AND NUTRITIONDEFINITION

Fitness is• The characteristics that

enable the body to perform physical activity

• The ability to meet routine physical demands with enough reserve energy to rise to a sudden challenge

• The body’s ability to withstand stress of all kinds

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BENEFITS OF FITNESS

• Sound, beneficial rest and sleep -- enables the body to– Repair injuries– Dispose of wastes

generated during activity

– Build new physical structures

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BENEFITS OF FITNESS (con’t)

• Improved nutritional health– Physical activity incurs

energy expenditure, enabling

– People eat more food, thereby

– Consume more nutrients and– Less likely to develop

deficiencies

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• Reduced fatness and increased lean body tissue– People who exercise have relatively less body

fat than sedentary people of the same body weight

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• Improved resistance to colds, other infectious diseases– Fitness builds immunity

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• Lower risks of some types of cancer– Lifelong exercise may help to protect against

colon cancer, breast cancer, and others

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• Reduced risk of heart, blood vessel diseases, and diabetes– Exercise that challenges the heart and

lungs• Slows the aging of the circulatory system• Lowers blood pressure• Slows the resting pulse rate• Lowers blood cholesterol• Normalizes glucose tolerance, especially

via the secretion of insulin

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• Reduced incidence and severity and depression– Physically active

people tend to deal better with stress

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• Improved self-image and self-confidence– The sense of achievement

that comes from meeting physical challenges promotes self-confidence

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• Longer life and improved quality of life in the later years– Active people have a

lower mortality rate than sedentary people

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COMPONENTS OF FITNESS

To be physically fit, a person needs to develop these components to meet the everyday demands of life

• Flexibility– Is the ability to bend and recover without injury

• Muscle strength– Is the ability of the muscles to work against resistance

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FITNESS AND NUTRITIONCOMPONENTS OF FITNESS (con’t)

• Muscle endurance– Is the ability of a muscle to contract repeatedly within a

given time without becoming exhausted

• Cardiorespiratory endurance– Is the ability to perform large-muscle, dynamic

exercise of moderate-to-high intensity for prolonged periods

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CONDITIONING BY TRAINING• Conditioning is the physical effect of

training– Results in improved flexibility, strength, and

endurance– Training is practicing an activity regularly

• Training is what you do, conditioning is what you get

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FITNESS AND NUTRITIONCONDITIONING BY TRAINING (con’t)

• Training should reflect the application of the progressive overload principle– A body system, in order to improve, must be worked at

frequencies, durations, or intensities that gradually increase physical demands• Frequency -- the number of occurrences per unit of time, e.g. the

number of exercise periods per week• Duration -- the length of time, e.g. the time spent in each exercise

session• Intensity -- the degree of exertion while exercising, e.g. the amount of

weight lifted or the speed of running

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• Applying overload – Be active all week

• Spend an hour per day doing moderate activity (e.g. brisk walking, swimming, cycling) -- don’t be a weekend athlete

– Train hard enough to challenge your strength or endurance once or twice per week, not every time you work out• Between times, do moderate workouts

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• Applying overload (con’t)– Pay attention to body signals

• Symptoms that demand immediate medical attention– Abnormal heartbeats– Pressure in the middle of the chest, teeth, jaw, neck, or arm– Dizziness– Lightheadedness– Cold sweat– Confusion

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FITNESS AND NUTRITIONCARDIORESPIRATORY

ENDURANCE• Is the component of fitness

relating to the ability of the cardiovascular system to sustain effort over a long time– Requires the heart and lungs to work

extra hard to deliver oxygen to the muscle cells for a sustained period

– Is therefore aerobic -- the energy producing process involving the immediate use of oxygen

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FITNESS AND NUTRITIONCARDIORESPIRATORY

ENDURANCE (con’t)• Benefits of aerobic training

– Increases muscle storage of glycogen– Increases capacity of mitochondria

to metabolize fat for energy– Lactic acid build-up begins to occur

at 70% of aerobic capacity instead of 50%

– “Spares” glycogen stores by using fat as energy source

– Minimizes excess fat stores and promotes weight loss

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FITNESS AND NUTRITIONCARDIORESPIRATORY ENDURANCE (con’t)

• Aerobic training can lead to cardiovascular conditioning, which is characterized by– An increase in total blood volume– A larger and stronger heart– Fewer heart beats– A slower pulse rate

• Anaerobic activity does not bring about cardiovascular conditioning but develops the strength and bulk of muscles

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FITNESS AND NUTRITIONENERGY SYSTEMS, FUELS, AND NUTRIENTS TO

SUPPORT ACTIVITY• The active body’s use of fuels

– At rest, body’ energy is derived• A little more than half from fatty acids• Most of the rest from glucose• A small percentage from amino acids

– At the beginning of exercise epinephrine and norepinephrine (stress hormones) signal the liver and fat cells to liberate their stored energy nutrients• Glucose• Fatty acids• A few amino acids

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FITNESS AND NUTRITIONENERGY SYSTEMS, FUELS, AND

NUTRIENTS TO SUPPORT ACTIVITY (con’t)

– How much of which fuels the muscles use during activity depends on• An interplay among the fuels available• The intensity and duration of the exercise• The degree to which the body is conditioned to

perform that activity

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FITNESS AND NUTRITIONENERGY SYSTEMS, FUELS, AND NUTRIENTS TO SUPPORT

ACTIVITY (con’t)• Carbohydrate and performance

– Carbohydrates are the most readily available sources of energy– How much carbohydrate you eat

• Partially determines how much glycogen you store• Influences the rate it will be used in any given activity -- the more

glycogen you store, the longer those stores will last as you work– Rate at which you use glucose also depends on

• The duration of the exercise• Its intensity• How well trained the person is

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• Carbohydrate and performance (con’t)– Glucose depletion brings on fatigue

• Drinking or eating sugary foods may be of value to endurance athletes who compete for 1-1/2 hours of non-stop exercise

• For everyday exercise, sugar will not help performance

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• Fat and performance– Fat is the most concentrated source of food

energy– Body fat stores can fuel hours of activity

without running out as long as the activity is not too intense

– After about 30 minutes of sustained moderate exercise, fat cells are significantly shrinking in size as they empty out their lipid stores

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SUPPORT ACTIVITY (con’t)

• Fat and performance (con’t)– Intensity also affects fat use

• As intensity increases, fat makes less and less of a contribution to the total fuel used

• Fat needs energy to be broken down into energy -- if you are breathing easily during exercise, your muscles are getting all the oxygen they need and are able to burn fat

– To burn the greatest amount of fat, a steady, long duration activity works best

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FITNESS AND NUTRITIONENERGY SYSTEMS, FUELS, AND NUTRIENTS

TO SUPPORT ACTIVITY• Fat and performance (con’t)

– Training also affects fat use• Stimulates the muscle cells to manufacture more and

stronger mitochondria (the cellular structures that conduct aerobic metabolism)

• Heart and lungs become better able to deliver oxygen to muscles at high activity intensities

• Hormones in the body of a trained person slow glucose release from the liver and speed up fat use instead

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• Protein and performance– Normally not used as fuel to any significant degree– Synthesis of protein is suppressed during periods of

exercise, but and for sometime afterward but rebounds

– The greater the glycogen stores, the less protein used

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TO SUPPORT ACTIVITY (con’t)

• Protein and performance (con’t)– Athletes, as well as people who work like

athletes, need about 25% more protein as sedentary people• Retain more protein in their muscles• Use more protein as fuel but at most contributes about

10% of the fuel used

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ACTIVITY (con’t)• Protein and performance (con’t)

– Diet affects protein use during activity• Diets adequate in energy and rich in carbohydrate result in less protein

use– Intensity and duration affect protein use during activity

• Aerobic activity of moderate intensity and long duration may result in depleted glycogen stores and somewhat more dependence on body protein for energy

– Training affects protein use• The higher degree of training, the less protein a person uses during an

activity

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TO SUPPORT ACTIVITY (con’t)

• Minerals and performance– Help regulate

• Muscle contraction• Conduction of nerve impulses• Clotting of blood• Heart rhythm

– Some minerals have added losses during exercise but research has not shown additional needs

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• Minerals and performance (con’t)– Supplementation is unnecessary, with the

exception of• Iron

– Physically active young women, especially those who engage in endurance activities are prone to iron deficiency

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SUPPORT ACTIVITY (con’t)• Minerals and performance (con’t)

– Iron (con’t)• Iron deficiency impairs physical performance

– Is crucial to the body’s handling of oxygen– Without available oxygen you can’t burn fat as fuel– You will be unable to perform aerobic activity and will tire

easily– Over-the-counter supplementation is available

» Absorption is poor» May mask other medical conditions

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ACTIVITY (con’t)• Minerals and performance (con’t)

– Iron (con’t)• Sports anemia

– A transient condition of low hemoglobin in the blood -- not a true iron deficiency condition

» Does not respond to iron supplementation» Blood plasma volume is expanded during strenuous activity

-- Red blood count per unit of blood is reduced however-- Red blood cells do not diminish in size or number-- Oxygen carrying capacity is not diminished

– Associated with early stages of sports training or other physical activity– Requires no treatment

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• Electrolytes and performance– Include the electrically charged minerals sodium,

potassium, chloride, and magnesium– Are lost from the body in sweat– A regular diet that meets energy and nutrient needs

also supplies all the electrolytes needed– Unless a person works up a drenching sweat,

electrolyte replacement is not necessary during exercise

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ENERGY SYSTEMS, FUELS, AND NUTRIENTS TO SUPPORT ACTIVITY

(con’t)

• Fluids and performance

– Working muscles produce heat as a

byproduct of energy metabolism

– Body cools itself by sweating -- each liter

of sweat dissipates almost 600 kcalories

of heat

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ENERGY SYSTEMS, FUELS, AND NUTRIENTS TO SUPPORT ACTIVITY (con’t)

• Fluids and performance

– Athletes should use thirst as a guide

– First sign of dehydration -- fatigue

– Overhydration (and accompanying hyponatremia) is a danger

– International Marathon Medical Directors Association recommends 12 - 25 oz fluid per hour

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HEART RATE AND AEROBIC CAPACITY

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FITNESS AND NUTRITIONHEART RATE AND AEROBIC CAPACITY

• The Karvonen formula is used to calculate your training heart rate

• Using your resting heart rate (pulse), estimate your maximum heart rate by subtracting your age from 220 -- never exercise at this rate

• Subtract your resting rate from your maximum rate and calculate 50%/60% to 75%/85% of this figure, depending on your fitness level

• This result, when added to the resting heart rate defines the bottom and top end of your target heart rate zone -- Your heart should beat in this range when you work aerobically

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KARVONEN FORMULA EXAMPLE (Lower target heart rate)• Find your resting heart rate -- 62• Estimate your maximum heart rate -- For a 25 year old, 220-

25 = 195– Never exercise at this rate

• Subtract your resting rate from your maximum rate -- 195-62 = 133

• Calculate 50% of this figure -- 133*0.5 = 67• Add the resulting number to the resting heart rate -- 67+62 =

129– Your heart should beat at least this fast when you work aerobically

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KARVONEN FORMULA EXAMPLE (Upper target heart rate)• Find your resting heart rate -- 62• Estimate your maximum heart rate -- For a 25 year old, 220-

25 = 195– Never exercise at this rate

• Subtract your resting rate from your maximum rate -- 195-62 = 133

• Calculate 85% (assuming a high fitness level) of this figure -- 133*0.85 = 113

• Add the resulting number to the resting heart rate -- 113+62 = 175– Your heart should not beat faster than this when you work

aerobically

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KARVONEN FORMULA EXAMPLE SUMMARY

For a 25 year old with a resting heart rate of 62 beats per minute:

– Lower target heart rate -- 129 beats per minute

– Upper target heart rate -- 175 beats per minute

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FOOD FOR FITNESS

• No one best diet supports physical performance

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FITNESS AND NUTRITIONFOOD FOR FITNESS

• Water is the most important nutrient– Exercise blunts the thirst mechanism, especially in cold weather– During exercise, thirst signals too late– To find out how much water you need to replenish exercise

losses• Weigh yourself before and after activity• One pound loss equals approximately two cups fluid (approximately

1/2 liter)– Plain cool water is best

• Rapidly leaves the digestive tract to enter the tissues• Cools the body

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FITNESS AND NUTRITIONFOOD FOR FITNESS

• Poor beverage choices– Caffeine

• Is a stimulant• Is also a diuretic -- can be especially hazardous for people competing

in hot environments– Alcohol

• Energy from alcohol breakdown generates heat but does not fuel muscle work because alcohol is metabolized in the liver (not in the muscle)

• Diuretic effect impairs the body’s fluid balance• Impairs the body’s ability to regulate its temperature• Alters perceptions• Slows reaction time• Reduces strength, power, and endurance• Hinders coordination in general

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FITNESS AND NUTRITION FOOD FOR FITNESS (con’t)

Dietary supplements– Protein powders

• Can supply amino acids -- lean meat, milk and legumes supply these also…and more

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FITNESS AND NUTRITIONFOOD FOR FITNESS (con’t)

• Dietary supplements– Amino acid supplements

• Single amino acids do not occur naturally in food and offer no benefit to the body

• Excesses of one amino acid can create such a demand for a carrier that it prevents absorption of another amino acid, leading to a deficiency

• Toxicity possible from those amino acids winning the competition when they enter the body in excess

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• Dietary supplements– Carnitine

• Often promoted as a ‘fat burner’• Supplementation neither raises muscle carntine

concentrations nor influences carbohydrate or fat oxidation• Causes diarrhea in about half of users• Milk and meat products are good natural sources --

supplementation is not needed

– Vitamin E• Some research findings support megadosing to prevent

oxidative damage to muscles• Studies as to the long term effect are lacking• Little evidence that it can improve performance

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• Dietary supplements– Creatine

• Theoretically, the more creatine phosphate in the muscles, the higher the intensity at which the athlete can train, which in turn improves performance

• Research is conflicting• Safety has not been established• Long term studies not available

– Caffeine• Research supports endurance enhancement effects• Adverse effects must be weighed

– Stomach upset– Nervousness– Irritability– Headaches– Diarrhea

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• Dietary supplements– Anabolic steroids

• Derived from testosterone -- promotes male characteristics and lean body mass

• Have toxic side effects

– DHEA & androstenedione• Are hormones made in the adrenal gland and are precursors to testosterone• Evidence to support fat burning and muscle building qualities is lacking• Long term effects unknown

– Human growth hormone• Often taken during growth years• Expensive• Side effects include acromegaly (over-enlarged body, diabetes, heart

disease, shortened life span)

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• Dietary supplements– Ephedra

• Promoted for short-term weight loss• Speeds heart rate and constricts blood

vessels• Particularly risky for those with heart

disease, high blood pressure, or who engage in strenuous exercise

• Linked to 155 deaths and dozens more heart attacks and strokes

• Banned by FDA in April 2004• U.S. District judge overrules FDA and

allows the marketing of low dose ephedra products in April 2005

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• Food choices must be made within the framework of the food pyramid -- should provide– 60% carbohydrate– 12-15% protein– 25% or less fat

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FITNESS AND NUTRITIONCONTROLLING WEIGHT

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• Contributions of physical activity to weight control– Directly increases energy output by muscles and

cardiovascular system– Increases basal metabolism– Helps to control appetite

• After a good workout, most people do not feel like eating

– Reduces stress– A fit person looks and feels healthy -- has high self

esteem

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• Weight loss without exercise can have a negative effect on body composition– Lose both fat tissue and lean tissue– Yo-yo effect

• Is repeated rounds of dieting without exercise• Person rebounds to a higher weight and higher body fat

content at the end of each round• Weight gained without exercising is mostly fat• Fat tissue burns fewer calories to maintain itself

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BODY COMPOSITION

• Determining body fatness– Techniques

• Underwater weighing– Determines body density

from which you can determine body fat percentage

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FITNESS AND NUTRITIONBODY COMPOSITION


• Measuring electrical impedance– Requires expensive equipment– Lean tissues are full of electrolyte-

containing fluids which conduct electricity

– Fat is a poor conductor

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• Determining fat-fold thickness

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• Body measurements

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% Body Fat Males Females

Normal 9 - 18% 14 - 28%

Overweight 18.1 - 22% 28.1 - 32%

Obesity > 22% > 32%

1 dnt 200 nutrition for health sciences fitness and nutrition

Documents

body weightfitness

body fat

routine physical demands

meeting physical challenges

later yearsactive people

activity regularlytraining

blood vessel diseases

improved quality of