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THE PHYSIOLOGY OF THE PHYSIOLOGY OF EXERCISEEXERCISE

11251125Steven C SeidemanSteven C Seideman

Extension Food Processing SpecialistExtension Food Processing Specialist

Cooperative Extension ServiceCooperative Extension Service

University of ArkansasUniversity of Arkansas

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INTRODUCTIONINTRODUCTION

The lack of exercise was never been a The lack of exercise was never been a problem until the middle of the 20problem until the middle of the 20thth century century when the industrial age, with its when the industrial age, with its automation, replaced much of the physical automation, replaced much of the physical work in the United States.work in the United States.

This module briefly discusses the history, This module briefly discusses the history, benefits, types and purposes of physical benefits, types and purposes of physical activity.activity.

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RECENT POPULARITYRECENT POPULARITY

Prior to the 1980s, physical education was Prior to the 1980s, physical education was required in most schools for purposes of required in most schools for purposes of preparing the youth for jobs that required preparing the youth for jobs that required physical strength.physical strength.

The majority of the physically demanding jobs The majority of the physically demanding jobs decreased and the general population believed decreased and the general population believed that physical exercise was not the best way to that physical exercise was not the best way to spend their leisure time.spend their leisure time.

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RECENT POPULARITYRECENT POPULARITY

Physical activity was replaced by computer Physical activity was replaced by computer games, television and other non-physical games, television and other non-physical activities.activities.

Along with this shift toward less physical activity, Along with this shift toward less physical activity, came the problems with feelings of stress, came the problems with feelings of stress, obesity, diabetes, heart disease, and rampant obesity, diabetes, heart disease, and rampant depression among other physical problems.depression among other physical problems.

The obvious solution is EXERCISE. The obvious solution is EXERCISE.

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RECENT POPULARITYRECENT POPULARITY

People who exercise today can be divided People who exercise today can be divided into several groups;into several groups;

1)People interested in weight loss1)People interested in weight loss 2) People that believe that exercise will 2) People that believe that exercise will

increase their longevity.increase their longevity. 3) People who believe ”If some exercise is 3) People who believe ”If some exercise is

good, more is better” and ultimately good, more is better” and ultimately become addicted to exercise.become addicted to exercise.

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People Interested in Weight People Interested in Weight LossLoss

If being overweight is caused by excessive If being overweight is caused by excessive caloric intake (a fact) there are two things we caloric intake (a fact) there are two things we can do to remedy it; 1) Reduce our intake (diet) can do to remedy it; 1) Reduce our intake (diet) and 2)Burn excess calories via exercise. and 2)Burn excess calories via exercise. More information on nutrition can be found More information on nutrition can be found elsewhere in this series (Introduction to Human elsewhere in this series (Introduction to Human Nutrition; Module 1219).Nutrition; Module 1219).As a guide, 30 minutes of vigorous exercise 3 to As a guide, 30 minutes of vigorous exercise 3 to 4 times per week is considered a good program 4 times per week is considered a good program to maintain one’s weight.to maintain one’s weight.

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People That Believe Exercise will People That Believe Exercise will Increase Their LongevityIncrease Their Longevity

There is very little scientific data to support the belief that There is very little scientific data to support the belief that exercise will increase longevity, however the quality of exercise will increase longevity, however the quality of life will generally improve.life will generally improve.For example, if you do not exercise, you may develop For example, if you do not exercise, you may develop diabetes. In today’s world of modern medicine, you may diabetes. In today’s world of modern medicine, you may live with diabetes the same number of years as if you live with diabetes the same number of years as if you didn’t have it, however, you may have your legs didn’t have it, however, you may have your legs amputated, go blind or suffer other circulatory diseases.amputated, go blind or suffer other circulatory diseases.Longevity tends to be more genetically determined and Longevity tends to be more genetically determined and not altered as much as most believe by lifestyle and not altered as much as most believe by lifestyle and exercise.exercise.

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““If Some exercise is good, more If Some exercise is good, more is better” Addictedis better” Addicted

These are the exercise fanatics.These are the exercise fanatics.They live to exercise as opposed to They live to exercise as opposed to exercise to live.exercise to live.These are the people who run several These are the people who run several miles a day and occasionally run 26 mile miles a day and occasionally run 26 mile marathons.marathons.They get literally “addicted” to exercise.They get literally “addicted” to exercise.

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THE BENEFITS OF THE BENEFITS OF EXERCISEEXERCISE

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The Benefits of ExerciseThe Benefits of Exercise

The benefits of exercise can be divided The benefits of exercise can be divided into several categories;into several categories;

1) Health Benefits1) Health Benefits

2) Mental Benefits2) Mental Benefits

3) Physical Benefits3) Physical Benefits

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HEALTH BENEFITSHEALTH BENEFITS

1) Heart Disease and Stroke1) Heart Disease and Stroke - Daily physical - Daily physical activity can help prevent heart disease and activity can help prevent heart disease and stroke by strengthening your heart muscle, stroke by strengthening your heart muscle, lowering your blood pressure, raising your lowering your blood pressure, raising your HDL (good cholesterol) and lowering your HDL (good cholesterol) and lowering your LDL (bad cholesterol), improving blood LDL (bad cholesterol), improving blood flow, and increasing you heart’s capacity flow, and increasing you heart’s capacity to work.to work.

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Health BenefitsHealth Benefits

2) 2) High Blood PressureHigh Blood Pressure – Regular exercise – Regular exercise reduces blood pressure in people with high reduces blood pressure in people with high blood pressure (hypertension).blood pressure (hypertension).

3) 3) DiabetesDiabetes – By reducing body fat, physical – By reducing body fat, physical activity can help to prevent and control type 2 activity can help to prevent and control type 2 diabetes.diabetes.

4) 4) OsteoporosisOsteoporosis – Regular weight-bearing exercise – Regular weight-bearing exercise promotes bone formation and may prevent many promotes bone formation and may prevent many forms of bone loss associated with aging.forms of bone loss associated with aging.

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Mental BenefitsMental Benefits

1) Exercise will reduce depression and anxiety and help 1) Exercise will reduce depression and anxiety and help you to better manage stress.you to better manage stress.

2) Promotes better, more restful sleep.2) Promotes better, more restful sleep.3) Long term, vigorous exercise causes the brain to release 3) Long term, vigorous exercise causes the brain to release

“dopamines” which create a feeling of well-being. This “dopamines” which create a feeling of well-being. This is often referred to as a “runners high”. It is your body’s is often referred to as a “runners high”. It is your body’s natural “high”. natural “high”.

4) Succeeding at setting a physical activity goal and 4) Succeeding at setting a physical activity goal and attaining that goal contributes to a feeling of attaining that goal contributes to a feeling of accomplishment.accomplishment.

5) Self esteem is often raised by reducing ones weight.5) Self esteem is often raised by reducing ones weight.

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Physical BenefitsPhysical Benefits

Physical exercise reduces some of the effects of Physical exercise reduces some of the effects of aging.aging.Keeps joints, tendons and ligaments flexible so Keeps joints, tendons and ligaments flexible so it’s easier to move around.it’s easier to move around.By increasing muscle strength and endurance By increasing muscle strength and endurance and improving flexibility and posture, regular and improving flexibility and posture, regular exercise can prevent back pain.exercise can prevent back pain.By losing weight via exercise, loss weight is By losing weight via exercise, loss weight is suspended in hip, knee and ankle joints thereby suspended in hip, knee and ankle joints thereby increasing their usefulness.increasing their usefulness.

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TYPES OF EXERCISETYPES OF EXERCISE

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Types of Physical ActivityTypes of Physical Activity

For weight control and general physical activity, For weight control and general physical activity, many types of daily activities can help;many types of daily activities can help;

SPORTSSPORTS

PLANNED EXERCISE PROGRAMSPLANNED EXERCISE PROGRAMS

HOUSEHOLD CHORESHOUSEHOLD CHORES

LAWN WORKLAWN WORK

All the above have some beneficial effect.All the above have some beneficial effect.

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Types of Planned ExercisesTypes of Planned Exercises

Exercises are broadly classified as one of Exercises are broadly classified as one of two types;two types;

1) Aerobic1) Aerobic

2) Anaerobic2) Anaerobic

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Aerobic ExerciseAerobic Exercise

Aerobic exercises are those that require a Aerobic exercises are those that require a substantial amount of oxygen over an extended substantial amount of oxygen over an extended period of time and causes you to breathe more period of time and causes you to breathe more deeply and your heart to work harder to pump deeply and your heart to work harder to pump blood. It is also known as “cardiovascular blood. It is also known as “cardiovascular exercise”. It improves the health of your heart, exercise”. It improves the health of your heart, lungs and overall cardiovascular system.lungs and overall cardiovascular system.Examples include walking, jogging, running, Examples include walking, jogging, running, aerobic dance, bicycling, rowing, swimming and aerobic dance, bicycling, rowing, swimming and cross-country skiing.cross-country skiing.

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Anaerobic ExerciseAnaerobic Exercise

Anaerobic exercise usually refers to Anaerobic exercise usually refers to resistance training whereby large amounts resistance training whereby large amounts of oxygen are not needed. of oxygen are not needed. Anaerobic exercise is done primarily for Anaerobic exercise is done primarily for increased muscle mass and bone increased muscle mass and bone strength.strength.Examples include weight lifting, sit-ups, Examples include weight lifting, sit-ups, push-ups, stretching, etc.push-ups, stretching, etc.

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Rate Limiting StepsRate Limiting Steps

In aerobic exercises where large groups of In aerobic exercises where large groups of muscles are used repeatably over a long period muscles are used repeatably over a long period of time, the rate limiting step is the update and of time, the rate limiting step is the update and utilization of oxygen.utilization of oxygen.

In anaerobic exercise, where only single or small In anaerobic exercise, where only single or small localized muscle groups are utilized, the rate localized muscle groups are utilized, the rate limiting step is in the number of sarcomeres limiting step is in the number of sarcomeres present in the muscles used. present in the muscles used.

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The Amount/Type of Exercise The Amount/Type of Exercise RecommendedRecommended

Most experts suggest 30 minutes/day of Most experts suggest 30 minutes/day of moderate-intense aerobic exercise 3 or moderate-intense aerobic exercise 3 or more times per week plus some form of more times per week plus some form of anaerobic exercise twice per week.anaerobic exercise twice per week.

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HOW TO GET STARTEDHOW TO GET STARTED

The single most important ingredient is The single most important ingredient is determination.determination.Decide on the best time of day (morning, noon Decide on the best time of day (morning, noon or evening).or evening).Decide on the type of activity (walking, jogging, Decide on the type of activity (walking, jogging, stretching etc).stretching etc).Set an exercise plan starting slow and easy and Set an exercise plan starting slow and easy and building up more as time passes.building up more as time passes.You don’t need fancy equipment- good shoes You don’t need fancy equipment- good shoes and appropriate clothing are enough.and appropriate clothing are enough.

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SAMPLE PLANSAMPLE PLAN

Here is a get-started simple plan.Here is a get-started simple plan. 1) Get up 1 hour earlier than usual.1) Get up 1 hour earlier than usual. 2) Do about 10 minutes of serious stretching 2) Do about 10 minutes of serious stretching

exercises.exercises. 3) Walk vigorously for 30 minutes.3) Walk vigorously for 30 minutes. 4) Do 10 to 20 sit-ups and push-ups.4) Do 10 to 20 sit-ups and push-ups. 5) Shower5) Shower 6) Go to work. Notice the improvement in attitude 6) Go to work. Notice the improvement in attitude

and reduced anxiety.and reduced anxiety.

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The Physiology of ExerciseThe Physiology of Exercise

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The Physiology of ExerciseThe Physiology of Exercise

This section will take you through the This section will take you through the concept of calories in foods, the body concept of calories in foods, the body tissues and the biochemistry of exercise .tissues and the biochemistry of exercise .

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FOODFOOD

Food consists of water, carbohydrates, fats/oils, Food consists of water, carbohydrates, fats/oils, proteins, vitamins and minerals.proteins, vitamins and minerals.Water is by far the most abundant but contains Water is by far the most abundant but contains no calories.no calories.Vitamins and minerals are present in very small Vitamins and minerals are present in very small amounts and do not contribute to calories.amounts and do not contribute to calories.This leaves us with carbohydrates, fats/oils and This leaves us with carbohydrates, fats/oils and proteins.proteins.

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CALORIESCALORIES

Calories associated with food Calories associated with food components;components;

Carbohydrates – 4.5 kcal/gramCarbohydrates – 4.5 kcal/gram

Proteins- 4.5 kcal / gramProteins- 4.5 kcal / gram

Fat- 9 kcal/ gramFat- 9 kcal/ gram

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Food ComponentsFood ComponentsCarbohydrates, fats and proteins are all Carbohydrates, fats and proteins are all inter-convertible in the body.inter-convertible in the body.This is a very important yet poorly This is a very important yet poorly understood concept.understood concept.If we eat a 3,000 calorie per day diet and If we eat a 3,000 calorie per day diet and only utilize 2,000 calories, the remaining only utilize 2,000 calories, the remaining 1,000 will be stored in the body in a priority 1,000 will be stored in the body in a priority order, usually as fat.order, usually as fat.This could conceivably mean that if you ate This could conceivably mean that if you ate 3,000 calories of only carbohydrates and 3,000 calories of only carbohydrates and protein, it would still be stored as fat if not protein, it would still be stored as fat if not utilized.utilized.

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The Burning of FoodThe Burning of Food

The Krebs cycle or tricarboxyclic acid The Krebs cycle or tricarboxyclic acid cycle utilizes carbohydrates, fats and cycle utilizes carbohydrates, fats and proteins to generate energy (ATP), COproteins to generate energy (ATP), CO22

and water (sweat).and water (sweat).

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PRIORITY OF NUTRIENT PRIORITY OF NUTRIENT UTILIZATIONUTILIZATION

Our body has a priority in which nutrients Our body has a priority in which nutrients (carbohydrates, fats and proteins) are utilized by (carbohydrates, fats and proteins) are utilized by various tissues.various tissues.

1) Nervous System1) Nervous System

2) Skeletal system-bones2) Skeletal system-bones

3) Muscle3) Muscle

4) Fat4) Fat

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Priority of Nutrient UtilizationPriority of Nutrient Utilization

If we exercise, our nutrient supply is used If we exercise, our nutrient supply is used at the muscle level and fat is never at the muscle level and fat is never formed. formed.

This same priority system reverses when This same priority system reverses when we experience lack of nutrients. We start we experience lack of nutrients. We start using fat for energy and then begin to burn using fat for energy and then begin to burn muscle as fat stores are depleted.muscle as fat stores are depleted.

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THE MARATHON RUNNERTHE MARATHON RUNNER

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THE MARATHON RUNNERTHE MARATHON RUNNER

Can you imagine what happens as a person Can you imagine what happens as a person runs a 26.25 mile marathon?runs a 26.25 mile marathon?

1) The first utilized component is glucose in the 1) The first utilized component is glucose in the blood. Blood sugar, or glucose, generally only blood. Blood sugar, or glucose, generally only lasts 15- 20 minutes. When we run low of blood lasts 15- 20 minutes. When we run low of blood glucose, our brain generally signals us that we glucose, our brain generally signals us that we are hungry. Immediately before a big race, you are hungry. Immediately before a big race, you often see athletes eating chocolates bars for that often see athletes eating chocolates bars for that instant energy.instant energy.

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THE MARATHON RUNNERTHE MARATHON RUNNER

2) As blood glucose starts to bottom out, the 2) As blood glucose starts to bottom out, the runner begins to utilize muscle glycogen. runner begins to utilize muscle glycogen. Muscle glycogen are long chain glucose Muscle glycogen are long chain glucose molecules stored in the muscle that look molecules stored in the muscle that look like sand under an electron microscope like sand under an electron microscope ( see next slide). This glycogen supply can ( see next slide). This glycogen supply can last 30 minutes to an hour.last 30 minutes to an hour.

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The Marathon RunnerThe Marathon Runner

3) As the glycogen level becomes lower, the 3) As the glycogen level becomes lower, the runner starts utilizing fat as energy. We all runner starts utilizing fat as energy. We all have stores of fat in various parts of our have stores of fat in various parts of our body. Distance runners generally have body. Distance runners generally have very little subcutaneous ( under the skin) very little subcutaneous ( under the skin) fat. Fat is also stored around kidneys, in fat. Fat is also stored around kidneys, in between muscle groups and even within between muscle groups and even within the muscle. the muscle.

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THE MARATHON RUNNERTHE MARATHON RUNNER

4) As the marathon runner begins to run out 4) As the marathon runner begins to run out of easily utilizable fat, they begin to utilize of easily utilizable fat, they begin to utilize muscle for energy. If not much muscle is muscle for energy. If not much muscle is used for energy by the runner, they will used for energy by the runner, they will recover from the run fairly quickly, recover from the run fairly quickly, however, if excessive muscle utilization however, if excessive muscle utilization has taken place, recovery could last over a has taken place, recovery could last over a month.month.

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DIETINGDIETING

The same chain of events (utilization of glucose, The same chain of events (utilization of glucose, glycogen, fat and then muscle) are exactly the glycogen, fat and then muscle) are exactly the same if one goes on a diet. same if one goes on a diet.

Anorexia Nervosa, a condition where a person is Anorexia Nervosa, a condition where a person is mentally repulsed by food, goes through the mentally repulsed by food, goes through the above process and if not treated, the person above process and if not treated, the person dies from digesting their heart ( a protein).dies from digesting their heart ( a protein).

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BODY TISSUESBODY TISSUES

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FAT CELLSFAT CELLS

Fat is the ultimate storage depot for unutilized energy.Fat is the ultimate storage depot for unutilized energy.Fat cells, call adipocytes are actually cells that develop Fat cells, call adipocytes are actually cells that develop and become filled with fatty acids.and become filled with fatty acids.If one exercise, the fatty acids are utilized for energy and If one exercise, the fatty acids are utilized for energy and one experiences a loss of weight. However, as one “falls one experiences a loss of weight. However, as one “falls off” the diet, the adipocytes refills with fatty acids quite off” the diet, the adipocytes refills with fatty acids quite easily. Therefore, to be successful, one must stay on the easily. Therefore, to be successful, one must stay on the diet and keep the fatty acids out of the adipocytes for 6 diet and keep the fatty acids out of the adipocytes for 6 months to a year in order for the adipocyte to disappear.months to a year in order for the adipocyte to disappear.

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MUSCLE AND MUSCLE MUSCLE AND MUSCLE FIBERSFIBERS

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MUSCLE FORMATIONMUSCLE FORMATION

Before we were born, our muscle cells formed Before we were born, our muscle cells formed into fibers whereby at birth our number of into fibers whereby at birth our number of muscle fibers were determined and cannot be muscle fibers were determined and cannot be changed.changed.We can increase the length and diameter of We can increase the length and diameter of muscle fibers through exercise.muscle fibers through exercise.Weight lifters subject muscle to increasing loads Weight lifters subject muscle to increasing loads and repetition whereby the muscle is damaged. and repetition whereby the muscle is damaged. After a day or two, they again subject muscle to After a day or two, they again subject muscle to damage.damage.

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Muscle FormationMuscle Formation

The body responds to this damage by not The body responds to this damage by not only repairing itself but repairing itself to only repairing itself but repairing itself to resist even damage. Correspondingly, the resist even damage. Correspondingly, the muscle get larger by adding more, muscle get larger by adding more, structural components called sarcomeres structural components called sarcomeres and by adding more mitochondria.and by adding more mitochondria.

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Muscle Fiber TypesMuscle Fiber Types

All muscle contain muscle fibers that are All muscle contain muscle fibers that are one of three types.one of three types.

RED, WHITE and INTERMEDIATERED, WHITE and INTERMEDIATE

Notice the difference between beef Notice the difference between beef (primarily red muscle fibers) vs chicken (primarily red muscle fibers) vs chicken breast ( primarily white muscle fibers)breast ( primarily white muscle fibers)

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Characteristics of Muscle Fiber Characteristics of Muscle Fiber TypesTypes

REDRED-More myoglobin-More myoglobin-More fat-More fat-More mitochondria-More mitochondria-Small in diameter-Small in diameter-Aerobic metabolism-Aerobic metabolism-Dark in color-Dark in color-High in iron-High in iron-Less glycogen-Less glycogen-Slow twitch but very strong-Slow twitch but very strong

WHITEWHITELess myoglobinLess myoglobin-Less fat-Less fat-Less mitochondria-Less mitochondria-Large diameter-Large diameter-Anaerobic metabolism-Anaerobic metabolism-Light in color-Light in color-Less iron-Less iron-More glycogen-More glycogen-Fast twitch but weak-Fast twitch but weak

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Muscle Fiber TypesMuscle Fiber Types

Intermediate muscle fibers are in between red Intermediate muscle fibers are in between red and white in characteristics.and white in characteristics.All muscles vary by location, type of exercise, All muscles vary by location, type of exercise, function, etc,function, etc,Some experts claim you can exercise to obtain a Some experts claim you can exercise to obtain a certain fiber type ( sprinter vs distance runner)certain fiber type ( sprinter vs distance runner)Some experts claim the muscle fibers are Some experts claim the muscle fibers are genetically determined (take biopsy to determine genetically determined (take biopsy to determine your ability to either sprint or run distances).your ability to either sprint or run distances).

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MUSCLE FIBER EXAMPLESMUSCLE FIBER EXAMPLES

Duck breast muscle vs chicken breast Duck breast muscle vs chicken breast muscle.muscle.

Hummingbird vs crowHummingbird vs crow

Beef vs pork vs chickenBeef vs pork vs chicken

Support muscles vs muscles used for Support muscles vs muscles used for locomotion.locomotion.

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SUMMARYSUMMARY

Physical exercise has many benefits and should Physical exercise has many benefits and should certainly become a part of our lifestyle.certainly become a part of our lifestyle.

Understanding how the human body responds to Understanding how the human body responds to food and exercise at the tissue and cellular level food and exercise at the tissue and cellular level is important to developing a well-rounded is important to developing a well-rounded exercise program including both aerobic and exercise program including both aerobic and anaerobic types.anaerobic types.

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