Chapter 18Fitness and Health: Some Chemical

Connections

Daniel Fraser

University of Toledo, Toledo OH

©2004 Prentice Hall

Chemistry for Changing Times 10th editionHill/Kolb

Chapter 18 2

Fitness in America

• Ready access to food– Especially in last 50–75 years

• More people do not perform manual labor– Do not burn as many calories

• Estimated that 61% of population is overweight– ~26% in 2002 were obese

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Nutrition

• Require: fats, proteins, carbohydrates, vitamins, and minerals

• Get through balanced diet

• USDA recommends following the food guide pyramid

• USDA also encourages exercise

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Food Guide Pyramid

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Newer Food Guide Pyramid

• USDA currently trying to update food guide pyramid

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American Diet• Consume too many calories

– Average person should cut back

• Consume less fat– Especially saturated fats and trans fatty

acids– Consume less partially hydrogenated

vegetable oils

• Consume less red meat– Consume less fat and protein

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Vitamins and Minerals

• Vitamins: substances required by human body but cannot manufacture

• Minerals: inorganic elements that body needs

• Recommended daily allowance (RDA) – Excesses of any nutrient will be stored or

excreted

• Example: excess turned into fat, not muscle

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Daily Reference Intake (DRI)

• Established amount required for males and females at different ages

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Nutritional Supplements

• Not required for healthy individuals eating a well-balanced and healthy diet

• Times requiring extra vitamins: rapid growth, pregnancy, lactation, and recovery from disease

• In small doses vitamins are nontoxic but, in large doses, they may be– Especially fat-soluble ones

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A and B Vitamins

• Vitamin A: essential for vision, development, and skin maintenance– Can obtain from -carotene– Too much can increase risk of bone

fractures later in life

• Vitamin B family– Many sources

– No toxicity for B vitamins except B6, may cause neurological problems

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C and D Vitamins

• Vitamin C: essential to maintain collagen and immune system– Lack of it causes scurvy– Too much gets excreted

• Vitamin D: steroid-type vitamin– Promotes absorption of calcium and phosphorus– Too much may lead to formation of calcium

deposits

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Vitamin E

• Vitamin E: seems to have value in maintaining cardiovascular system

• Has anticoagulant properties

• Rats deprived of it suffer from sterility

• Protects against free radicals

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Electrolytes

• Substances that conduct electricity when dissolved in water

• Sodium, potassium, and chloride ions are major electrolytes

• Need to be replaced

• Sports drinks probably needed only by endurance athletes

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Water

• Best way to replace is to drink it

• Caffeine and alcohol are diuretics

• Thirst is delayed response– Drink on regular basis

• Lack of water can lead to heat stroke– Result of dehydration and overheating

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Weight Loss Diets

• Cut out 100 kcal/day and keep normal activity– Lose 1 lb in 35 days– People seldom so patient

• Diets below 1200 kcal/day likely lead to nutritional deficiency– Body will slow down metabolism to conserve energy

• Cannot return to old habits once weight is lost

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Example 18.1  Diet CalculationsIf you ordinarily expend 2200 kcal/day and you go on a diet of 1500 kcal/day, how long will it take to diet off 1.00 lb of fat?

Exercise 18.1AA person who expends 1800 kcal/day goes on a diet of 1200 kcal/day without a change in activities. Estimate how much fat she will lose if she stays on this diet for 3 weeks.

Exercise 18.1BA person who expends 2200 kcal/day goes on a diet of 1800 kcal/day and adds exercise activities that use 180 kcal/day. Estimate how much fat he will lose if he stays on this program for 3 weeks.

SolutionYou will use 2200 – 1500 = 700 kcal/day more than you consume. There are 3500 kcal in 1.00 lb of fat, and so it will take

3500 kcal x ––––––– = 5 days1 day

700 kcal

(Keep in mind, however, that your weight loss will not be all fat. You will probably lose more than 1 lb, but it will be mostly water with some protein and a little glycogen.)

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Crash Diets

• Quick = Quack• Loss of water using diuretics

– Weight comes back when body is rehydrated

• Low carbohydrate diets deplete body of glycogen: carbohydrate storage– 1 lb glycogen has 3 lb water held to it– Replace when carbohydrates are consumed

• Crash diets tend to be low in some nutrients

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Exercise• Studies consistently show that people

who exercise live longer– Sick less often and have fewer signs of

depression

• Metabolic rate increases during exercise and stays higher several hours afterward

• Moderate exercise (<1 hr/day) does not cause an increase in appetite

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Example 18.2  Exercise CalculationsA fast game of tennis burns off about 10 kcal/min. How long would you have to play to burn off 1 lb of adipose (fat) tissue?

Exercise 18.2AWalking a mile burns off about 100 kcal. How far do you have to walk to burn off 1 lb of fat?

Exercise 18.2BA moderately active person can calculate the calories needed each day to maintain proper weight by multiplying the desired weight (in pounds) by 15 kcal/lb. How many calories per day do you need to maintain a weight of 120 lb?

SolutionOne pound of adipose tissue stores 3500 kcal of energy. To burn it off at 10 kcal/min requires

3500 kcal x –––––– = 350 min1 min

10 kcal

It takes 350 min (5 hr 50 min) to burn off 1 lb of fat, even with a fast-paced game of tennis. (You don’t have to do it all in one day.)

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Level of Fitness

• Usually measures fatness

• Males require 3% body fat

• Females require 10–12% body fat

• Hard to measure accurately– Not indicated by weight or weight/height

ratio

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Measuring Fitness

• Estimate fat by measuring density of body– Fat less dense than muscle– Requires dunk tank

• Measure hip to waist ratio– Males <1– Females <0.8

• Using skinfold calipers – not accurate

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Body Mass Index• Attempts to measure fat in body

• BMI = 705 x body weight (lbs)/[height (in)]2

• BMI 18.5–24.9 average

• BMI 25–29.9 overweight

• BMI >30 obese

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Example 18.3  Body Mass IndexWhat is the BMI for a person who is 6 ft 2 in. tall and weighs 230 lb?

Exercise 18.3AWhat is the BMI for a person who is 5 ft tall and weighs 120 lb?

Exercise 18.3BWhat is the maximum weight, in pounds, that a person 5 ft 10 in. tall can maintain and have a BMI that does not exceed 25.0?

SolutionThe person’s height is (6 x 12) + 2 = 72 + 2 = 74 in.

BMI = –––––––– = 29705 x 23074 x 74

The body mass index is 29.

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VO2 Max

• Maximum amount of O2 a person can use per kilogram of body weight

• The higher, the better

• Requires complex equipment to measure accurately

• Limited by how fast muscles use oxygen and how fast O2 can be transported to muscle

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Chemistry of Muscles

• ~600 muscles in human body

• Heart most important one– Need to keep healthy

• Training effect: person who exercises regularly is able to do more physical work with less strain

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Energy Conversion

• Energy currency in body is adenosine triphosphate (ATP)

• All food must be converted to ATP for use in muscles

• Use constantly for cell repair, nerve impulse, and body temperature regulation

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Muscles

• Made of actin and myosin

• Work together when muscles contract

• Use ATP to contract

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Exercise• Aerobic exercise

– Muscle contractions that occur in presence of O2

– Typically during endurance events

• Anaerobic exercise– Insufficient O2 available

– Build up lactic acid, causing muscle fatigue

– Oxygen debt: need O2 to get rid of lactic acid• Must be repaid

– Typically during sprints and weight training

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Muscle Fibers• Two types, one for each type of exercise

– Slow twitch: aerobic work– Fast twitch: anaerobic work

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Building Muscle

• Endurance training increases myoglobin levels, respiratory capacity, and faster O2 transport– Does not necessarily increase size of muscles

• Strength training increases size and strength of muscles– Does not necessarily increase respiratory

capacity

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Drugs and Athletics

• Restorative drugs: alleviate pain– Include painkillers, reduce swelling

• Stimulant drugs: try to improve performance– Include caffeine and amphetamines

• Anabolic steroids– Increase muscle mass more rapidly– Side effects: impotence, testicular atrophy, liver

damage, growth of breasts, …

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Exercise and the Brain

• With training, brain will produce endorphins– Natural painkillers

• May produce euphoric high during or after run– Runners may suffer withdrawal if they do not run

regularly

• Regular exercise increases blood supply to brain

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Smoking• Associated with 24 different diseases

• Increases risk of stillborn babies

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Chemistry of Sports Materials• Tend to try to make sports equipment lighter

and stronger– Large use of plastics

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End of Chapter 18

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