Lecture  |  Study Guide | 

Major Assignment

Lecture 

Lecture - Chapter 11 Nutrition, Exercise, and Sports
(On our syllabus, this is actually Week 5)

The benefits of regular, moderate physical activity suggests that exercise is medicine.  There is evidence that regular physical activity slows the aging process.

Fitness:
*  the ability to perform physical activity
*  includes flexibility, strength, and endurance
*  ability to meet routine physical demands with enough reserve energy to rise to a
    physical challenge
*  ability to withstand stress of all kinds, including physical, emotional, mental, and
    psychological stresses.

Opposite of fitness = sedentary life
*  sitting down a lot
*  physically inactive

Minimal physical effort = weak  = unfit = unwell.

Physical inactivity is linked to chronic disease:
*  cancer
*  stroke
*  diabetes
*  high blood pressure
*  heart disease

Even moderate activity provides health benefits.

Consider applying the dietary principles of variety, balance, and moderation to your exercise plan:

"More people need to get moving more of the time."

Regular physical activity is a vital part of a healthy lifestyle, ideally consisting of a total of at least 30 minutes (and preferably 60-90 min., especially if weight loss/weight control is an issue) of aerobic activity on most (or all) days. Physically active people show lower risks of cardiovascular disease, type 2 diabetes, obesity, and other common chronic diseases.

As people start exercising regularly 4-5X/week, they experience a "training effect". Initially, these individuals might be able to exercise for 20 minutes before tiring. Months later, exercise can be extended to an hour before they feel tired. During the months of training, muscle cells have produced more mitochondria and thus can burn more fat. Training also increases the number of capillaries in muscles, which increases oxygen supply to the muscles. As a result, lactic acid production from anaerobic glucose metabolism decreases. Because it contributes to short-term muscle fatigue, the less lactic acid produced, the longer the exercise can be sustained. Other contributors to the training effect include increased aerobic efficiency of the heart and muscles, and elevations in muscle triglyceride content, with an enhanced ability of muscles to use triglycerides for energy needs.

Benefits of fitness:
*  restful sleep
*  nutritional health
*  optimal body composition
*  optimal bone density
*  resistance to colds/other infectious diseases
*  low risk of colon and breast cancers
*  strong circulatory and respiratory systems
*  low risk of cardiovascular disease
*  low risk of diabetes
*  low incidence/severity of anxiety and depression
*  high quality of life 

Components of health related physical fitness:
*  cardio-respiratory endurance = aerobic fitness
*  muscular strength
*  muscular endurance
*  flexibility

Where do muscles get the energy to contract during exercise?
This energy comes from the chemical energy released by the breakdown of food.
As carbohydrates are broken down to glucose, energy is released; as protein is broken down to amino acids, energy is released; as fat is broken down to fatty acids, energy is released.

This released energy is used to manufacture a substance called ATP, adenosine triphosphate.

ATP (adenosine triphosphate):
*  chemical energy is stored as ATP
*  ATP is the main energy for cells; ATP is the currency that runs cells
*  used for ion pumping, enzyme activity, muscle contraction, etc.; ATP is the fuel that
    runs the body machinery
*  immediate source of energy for body functions
*  one of the reasons for eating CHO, fat, and protein is to make ATP
*  cells constantly use and reform ATP; this is done over and over again.

Food provides - CHOs, fats, and proteins.
When CHOs are digested, glucose is the result and energy is released. The muscles can't use this energy until it has been transformed in the muscle cells to ATP. ATP is the fuel used for muscle contraction.

When fats are digested, fatty acids are the result and energy is released. The muscles can't use this energy until it has been transformed in the muscle cells to ATP. ATP is the fuel used for muscle contraction.

When proteins are digested, amino acids are the result and energy is released.  The muscles can't use this energy until it has been transformed in the muscle cells to ATP. ATP is the fuel used for muscle contraction.

There are 2 systems in the body that can produce ATP: the aerobic and anaerobic systems.

The anaerobic system does not require oxygen to produce energy. the prefix "an" means without; "aerobic" means oxygen.

Anaerobic ATP Production:
*  Can only use glucose/glycogen as an energy source
*  ATP produced at the beginning of exercise
*  ATP produced during short-term, high-intensity exercise lasting 30-60 seconds.
*  Muscles produce large amounts of lactic acid

Disadvantages:
*  The body can't sustain ATP production for long
*  Only ~5% of energy available from glucose as it's broken down; this is inefficient.
*  Accumulation of lactic acid increases the acidity of muscle cells. High acidity inhibits
    activity of key enzymes in glucose breakdown, so anaerobic ATP production slows and
    fatigue sets in.

The aerobic system does require oxygen to produce energy.

Aerobic ATP Production:
*  This is in effect when physical exercise lasts longer than 60 seconds.
*  This system uses CHOs, fats, and proteins to make ATP.
*  CHOs and fats are the primary sources of energy for ATP production.
*  At the beginning of physical exercise, CHOs are the principle food stuff that's broken
    down during ATP production.
*  During prolonged physical exercise (20 minutes or longer), there's a shift from CHO
    to fat as an energy source.
*  This pathway is used when physical activity is of moderate to low intensity.

Yes, it's possible for your body to be producing ATP through both anaerobic and aerobic systems during your exercise session. You could be out walking. You're going along at a moderate intensity (you can talk and/or sing at this level of intensity), your body is producing ATP aerobically;  all of a sudden you're chased by a ferocious dog. During the sprint, your body is producing ATP anaerobically. When you slow down again, your body switches to making ATP aerobically again.

Yes, you are taking in oxygen/breathing while you're exercising both aerobically and anaerobically. But during anaerobic exercise your muscles aren't receiving oxygen. Your exercise intensity is so great your muscles are forced to make ATP anaerobically. Your body can't sustain this for long; after ~60 seconds your muscles begin to ache. 

Which type of fuel the muscles use depends on:
*  which fuels are available
*  the intensity of the exercise
*  the duration of the exercise
*  the body's prior conditioning

Fat = main fuel.
The rate at which muscles use fat depends on:
*  the more trained a muscle, the greater the ability to use fat for fuel.
    Why?  There are more and larger mitochondria present in aerobically trained muscles.
    So muscle cells can produce more ATP aerobically.
*  The greater the concentration of fatty acids (the breakdown of products of fat) in the
    blood stream, the greater the use of fat by muscles.
*  As exercise duration becomes longer (more than 20 minutes), fat use predominates,
    especially at low to moderate activity rates.

Protein:
*  Amino acid (the breakdown products of protein) use for fuel is small compared to
   glucose and fat.
*  ~ 2-5% of body's energy needs are supplied by amino acids.
*  As much as 10% of energy needs can be supplied by amino acids during an endurance
    event. An endurance event is one lasting 90 minutes or longer.
*  Protein is used less in weight lifting type exercise than endurance exercise.
*  The primary fuel of weight lifting is  CHO.
*  Consuming high-CHOs, moderate protein foods immediately after a weight training
    workout enhances the anabolic effect of the activity.
    How?  Most likely by increasing the concentration of insulin and growth hormone in the
    blood.

Good eating habits, physical training, and genetic endowment contribute to good athletic performance and endurance, and helps speed the repair of injured tissue.

All athletes would do well to plan a diet following the Food Guide Pyramid. High CHO foods should be emphasized, and these should dominate in pre-event meals. Protein intake above 2X the RDA is not supported by scientific evidence. Most athletes easily consume enough protein from typical food choices. If nutrient supplements are used, dosages generally should not exceed the Upper Level set for each nutrient. Fluid should be consumed as liberally as possible before, during, and after an event. CHO and electrolytes in the fluid are especially helpful to help delay fatigue and maintain electrolyte balance when exercise duration is expected to exceed 60 minutes.

Physical fitness:
*  the ability to do moderate to vigorous activity without undue fatigue.
*  the greater one's fitness, the more fat is used to supply energy needed for activity,
    especially if the activity last for 20 minutes or more.

Target Heart Rate:
* the range that corresponds to an exercise intensity of approximately 60-85% of 
   VO2 Max.
*  this range of training results in improvement in aerobic capacity

VO2 Max = (V=volume; O2= oxygen; Max=maximum) 
*  the highest oxygen consumption achievable during exercise
*  a lab measure of endurance capacity of both the cardiovascular system and the
    exercising skeletal muscles.

Since we're not in a lab setting with elaborate equipment to measure our VO2 Max, we'll measure our Target Heart Rate instead.

Do the following calculations:
a)  Maximal Heart Rate:
                                      220 - age = _____ heart beats/minute

For example: 220-20 years= 200 heart beats/minute

b)  Target heart rate (THR):

For example: using 200 heart beats/minute for a 20 year old, do the following calculations:

                       200 heart beats/minute  X 0.60 = _____ heart beats/minute
                       200 heart beats/minute  X 0.85 = _____ heart beats/minute

This 20 year old's Target Heart Rate would be between 120-170 heart beats/minute.

Keeping their heart beat in this range during aerobic exercise would allow for improvement in aerobic capacity.

The following activity is for practice. You will not turn-in anything to me.

Activity 1:  What is your THR?

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Study Guide

1. What are the guidelines for developing and maintaining physical fitness?

2. What are the guidelines for obtaining health benefits?

3. Provide 3 definitions of fitness. Define sedentary.

4. What does research state about regular physical activity? What percent of the U.S.
   adult population exercises regularly? What degenerative diseases are directly linked to
   the lack of physical activity? How does being physically inactive relate to early death? 

5. Explain how being more active impacts the following: sleep, nutritional health, body
    composition, bone density, immunity, risk for cancer, circulation and lung function, risk
    for cardiovascular disease, risk for type 2 diabetes, gallbladder disease, anxiety and
    depression, self-image, and longevity.

6. Define the following components of a sound fitness program: flexibility, muscle
    strength, muscle endurance, and cardio-respiratory endurance. Explain the following
    principles of conditioning: progressive overload, frequency, intensity, duration,
    warm-up, and cool-down.

7. What are the benefits of weight training? What are the benefits of aerobic training for
    cardio-respiratory endurance? For muscle conditioning? Provide an example of a
    balanced fitness program.

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