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HOME CONTENT PREPARATION ANALYSIS DESIGN APPENDICES GLOSSARY
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SECTION II - ANALYSIS
LESSON 6 - FLEXIBILITY LESSON 7 - ENDURANCE LESSON 8 - STRENGTH LESSON 9 - SKILL
LESSON 10 - BODY COMPOSITION LESSON 11 - ENERGY LESSON 12 - NUTRITION
LESSON 11
ANALYSIS OF ENERGY
Energy: Fuel, Work, and Fatigue
Objectives
Upon completion of
this Lesson 11, you should be able to complete the following activities:
v Describe two forms of energy in the body.
v Define
adenosine triphosphate and explain how it is used in body.
v Explain
the relationship between energy production and level of physical activity.
v List
and describe the three energy systems in the body that are responsible for the
resynthesis of ATP.
v Define fatigue and explain the mechanisms that cause it.
The processes of the body
utilize two forms of energy to carry out its many functions, chemical and
electrical. Chemical energy is the energy possessed by compounds
such as adenosine triphosphate (ATP), a special substance in the cell that
provides energy, and water (HOH). The second, electrical energy;
is a result of the flow of electrons along a conductor. Both chemical and
electrical energy play major roles in the energy changes of the body. There are
two kinds of energy changes, potential and kinetic. Potential energy
is energy stored or inactive and kinetic energy is energy in
action. Both potential and kinetic energy become apparent when electrical and
chemical energy are converted from one to the other. For example ATP, a
compound stored in muscle, possesses potential chemical energy, but when it is
used to fuel the contraction of muscle, it is converted into kinetic energy.
Chemical energy is the most
fundamental form of energy in the life process. Every thought, every nerve
impulse, every muscle movement, and every activity of any sort shown by living
organisms is ultimately traceable to the release of chemical energy. This
includes the functions of the cardio respiratory system and its ability to
supply oxygen to its own fibers, as well as all other cells of the body.
The cardio respiratory system
contributes to the energy producing processes of the body by delivering oxygen
and other nutrients to exercising muscle cells and removing carbon dioxide and
other waste products from the muscles. However, it is the electrochemical
energy produced, when the heart, lungs, blood vessels, and blood perform their
roles that makes improvement possible in the functions of all system of the
body. Therefore, knowledge of the energy producing functions at all levels of
the organizational structural hierarchy of the body is the basis
for understanding how the systems of the body respond to physical activity.
This can be clearly demonstrated in an explanation of how the muscular system
produces energy to perform work.
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The organizational hierarchy of
the body is the mechanism for loss, maintenance, or improvement of body
functions in the seven areas of fitness: flexibility, cardio
respiratoryendurance, strength, skill, body fat composition, energy, and
nutrition. This mechanism begins at the chemical level and continues through
each higher level up to the organ systems level, by effectuating gradual changes
in the functions of the body at each level. As participation in physical
activities increases, so, also, do the activities of the chemicals of the body,
its cells, tissues, organs, and organ systems. Ultimately, all levels of the
organization hierarchy of the body are changed to reduce, maintain, or increase
the ability of the organs systems of the body to perform their many functions.
According to the level of physical activities experienced, the body is
constantly changing no matter how low or high one’s level of physical
activities. This is true because living is a continuous process comprised of
the many complex functions of the body;Ftthese functions change at all levels of
the structural hierarchy in response to physical activity. The body may
experience loss of functioning, if activities are reduced for extended periods
of time; it may experience the same level of functions, if the activities
experienced by the body are neither increased or decreased. Thus, if the
desired effect is an increase in ability of the body systems to function, this
effect can be achieved by gradually exposing the body to progressively higher
levels of activity.
The length of mmuscle becomes shorter, is maintained, or becomes longer, due to the level of or lack of physical activity experienced. Also, flexibility is lessened, maintained, or increased in accordance with the level of activity experienced; and as the ability of the body cells to supply and use oxygen is changed, cardio respiratory endurance is decreased, maintained, or increased. Likewise, as the ability of the muscles to work against changes in resistance, maximum strength or muscular endurance is decreased, maintained, or increased. The body is always changing, but whether the changes result in loss, maintenance, or improvement of fitness depends on the specific activities practiced and the frequency, intensity, and duration (time) of the activities. This approach to effectuating change in the body is the basis for selecting frequency of training, intensity of training, and the time (length or duration) of training; this model is known as the F. I. T. Model (frequency, intensity, and time model) and determines how much energy will be produced during a training session. All aspects of the chemical activity responsible for energy production, during exercise, contribute to the changes in metabolism, which is the chemical process that make it possible for the cells to continue living. This process is known as homeostasis.
It is known that the greater proportion of the chemical reactions in the cells are concerned with making the energy in foods available to the various cells of the physiological systems. For instance, energy is required for muscular activity, secretions of glands, synthesis of substances in the cells, and absorption of foods from the gastrointestinal tract. Adenosine triphosphate (ATP) plays a key role in making the energy of the foods available for all of these purposes.
ATP is a chemical compound that is present in all cells, so, essentially, all physiological mechanisms that require energy for operation obtain it directly from ATP. This means that the body needs and therefore has to maintain a supply of ATP at all times. To achieve this goal, ATP is reformed from substances released with the release of energy. This is why ATP has frequently been called the energy currency or fuel of the body that can be gained and spent again and again. The ability to exercise or do work depends on this cyclical process or using, restoring, and reusing ATP.
Three ATP and Energy Producing Systems
Carbohydrates, fats, and proteins are used to produce large amounts of ATP, which in turn can be used for an energy source for many cellular functions. The principal functions of ATP in the body are as follow: 1) to energize the synthesis of important cellular components, 2) to energize muscle contraction, and 3) to energize active transport across membranes (absorption from the intestinal tract, absorption from the renal tubules, formation of glandular secretions, and nerve impulse transmission).
There are three energy systems that produce ATP in the body. The first two are anaerobic systems, which means that they produce energy derived from foods without the simultaneous utilization of oxygen as a part of the chemical processes. The third system is aerobic, which means energy can be derived from foods only by metabolism or chemical processes that utilize oxygen. Carbohydrates are the only significant foods or nutrients that can be utilized to provide energy without utilization of oxygen. When a person stops breathing, he or she already has a small amount of oxygen stored in their lungs and an additional amount stored in the hemoglobin of their blood. This amount of oxygen is sufficient to keep the metabolic processes functioning for only about two. Thus, it is essential that an additional source of energy is capable of providing the energy required to sustain the metabolic processes of cells.. This means that the energy supplied by the potentially strenuous bursts of anaerobic energy, which exists without the use of oxygen for approximately two minutes, extends the period of metabolic activity to approximately four minutes. At this point, the physiological activities of the cells fail in their ability to sustain life, because energy is no longer being produced. In order for energy producing chemical activity to continue beyond two minutes (anaerobic energy), oxygen must be present (aerobic energy). Also, the amount of oxygen required increases as the amount of energy produced increases.
It is common knowledge that muscles can perform extreme feats of strength for a few seconds but are much less capable during prolonged activity. However, during periods of rest the reduction in the need for oxygen by other cells allows the build up of the by products, lactic acid or waste that causes muscle fatigue, to be dissipated . The two anaerobic energy systems, which permits fatigue to occur rather rapidly, are the creatine phosphate system(ATP-CP) and anaerobic glycolysis. The ATP-CP energy system can produce ATP anaerobically for up to 10 seconds. Anaerobic glycolysis or the lactic acid systems can produce ATP anaerobically up to 2 minutes. The third system is the oxygen system; it can produce large amounts of ATP for extremely long periods of time. This is true only when there are sufficient quantities of oxygen present and the steady and continuous supply of oxygen needed to convert carbohydrates to energy is acquired. As long as there is sufficient oxygen, fatigue may be avoided for long periods of time, as is the case of a 5 to 27 mile marathon run.
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Overcoming Fatigue
Physiologists have recognized
that the human body possesses great wisdom ever since they realized that little
goes wrong with the trillions of cells comprising the body and within its
thousands of physiological processes, which takes place every moment of
life. Walter Cannon, an American physiologist of the early twentieth century,
spoke of the “wisdom of the body,” and coined the word homeostasis(ho
me o sta¢sis) to describe the ability
of the body to maintain relatively stable internal conditions even in the face
of continuous change of the outside world. Although the true meaning of
homeostasis is unchanging, this term does not suggest static. To the contrary,
homeostasis refers to a dynamic state of equilibrium, or balance, in which
internal conditions change and vary within relatively narrow ranges. This
balance is essential for life, as we know it.
The body is said to be in
homeostasis when its cells receive what is needed to function
smoothly. However, the ability of cells to function smoothly is affected by
every level of the structural hierarchy of organization in the body. Virtually
every level plays a role in maintaining the constant but dynamic internal
conditions that exist every moment. For example, adequate amounts of blood,
blood pressure, rate of transport, cellular pressure, and nutrients must,
constantly, be monitored and maintained so that chemical activities, cells,
tissues, organs, and organ systems preserve complimentary functions. The
process is no different, if physical activities are the reason for homeostatic
change. When the body functions are stimulated by physical activity all levels
of the organizational structure enter into complementary functions to maintain
homeostasis. As the levels of physical activities change, cellular functions
are stimulated proportionately to trigger the adaptations needed to maintain
homeostasis. Thus, the complementary functions, at all levels of the body’s
organization, produce results that may cause loss, maintenance, or improvement
of the specialized functions in response to the physical activities
encountered.
However, as an athlete trains
to prevent loss and to make gains in his or her ability to perform in sport,
they will experience limitations that are the result of fatigue. Fatigue is a
condition that ultimately occurs when exercise is intense and continues long
enough for certain conditions to prevail. An athlete should be familiar with at
least three conditions that causes fatigue. They are as follow:
1) When the supply of ATP that is produced by the ATP-CP or phosphagen system is
depleted (10 seconds), the
metabolic processes are changed and fatigue occurs;
2) When lactic acid accumulates during
anaerobic glycolysis and there is an insufficient amount of oxygen present to
produce more ATP the metabolic processes are changed and fatigue occurs;
and
3) When there is not enough glucose present
with sufficient amounts of oxygen in the body to trigger the use of
fat during long-term ATP production, by the oxygen or aerobic energy system,
the metabolic processes are
changed and fatigue occurs.
When fatigue occurs, muscle contraction is diminished or loss, which causes the inability of an athlete to perform at his or her normal level. Athletes perform at high levels of intensity as long as there is a sufficient amount of ATP present to fuel their muscle contractions. Thus, each of the three energy systems should be trained to improve an athlete's ability to produce ATP. This should be done through the use of the FIT Model. For example, Interval training, which is repeated bouts of intense exercise separated by rest periods of various lengths, is used to train the two anaerobic systems (ATP-CP and lactic acid systems); and long periods of continuous exercise with low to moderate intensity is used to train the aerobic system (oxygen system). The end result is that fatigue can be pushed back from a point in distance and time to permit higher levels of performance after proper training of each of the three ATP or energy producing systems. Development of the three energy systems brings about changes in performance that is caused by the ability of the muscles to produce and utilize greater amounts of ATP, which includes an increase in the ability of the body to store and utilize oxygen.
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The Three Phases of A Training Session
It is important to know and to understand each component of fitness in relationship to its effect on energy production, during each training period. For instance, a training session that emphasizes cardio respiratory training requires emphasis on a different energy system than strength exercises. This approach to planning should also be applied to the three essential divisions of a training session: 1) Warm-up, 2) Workout, and 3) Cool-down. Proper management of training, during each of the three divisions of training, must be managed with respect to energy production, which is directly related to the energy system utilized to produce ATP for muscle work. As the intensity of exercise increases energy production increases and vice versa. An understanding of the three phases of training in relationship to intensity and the energy systems that are relied upon to deliver ATP, is instrumental in reducing risks of injury or illness and achieving the desired training effect, during a training sessions.
The warm-up is used to gradually increase the heart rate, blood pressure, oxygen consumption, dilation of blood vessels, elasticity of the active muscles and the heat produced by active muscle groups. The components of the warm-up are graduated aerobic activity and flexibility. Examples of appropriate aerobic activities are jogging or slow tempo rhythmic calisthenics. Flexibility exercises should be specific to the biomechanical nature of the primary conditioning activity. For instance, calf, quadriceps, and Achilles stretching should precede running.
The workout is used to emphasize conditioning of the fitness component (flexibility, cardio respiratory endurance, strength, or body fat composition) that an athlete is interested in improving. There are four criteria that must be addressed in each of the three conditioning phases of a training session: mode of exercise, frequency of exercise, intensity of exercise, and duration of exercise (time). More than one component of fitness and other principles of fitness training must be included in each workout to ensure balance and control of the training effect, which must always be achieved, if progressive improvement is to be experienced
When the cool down period is completed the heart rate and breathing rate are reduced to near the rate they were before exercise. Thus, much of the waste that was accumulated in muscle tissues and blood, during the workout, is removed in this phase of a training session. The goal of the cool down is to reduce body temperature, prevent soreness, and off sets blood pooling, which causes undesirable stress on the cardiovascular system. This makes having a plan to cool the body down very important. So, to minimize the risks of experiencing the ill effects of training, a cool down period should be included at the end of every training session. Failure to do so may become evident before and during the next training session.
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Fitness Goals and Cycles of Periodization
An understanding of how energy is produced and used to effectuate changes in body functions to produce higher levels of performance in sports is fundamental to goal setting and the establishment of cycles of progression (periodization). Successful planning must include the establishment of realistic goals, and the goals should focus on both, short and long term outcomes. Long term goals embrace the big picture. That is, they address outcomes for the year or as in the case of Olympic participants, they are relegated to four years. The main period for which a fitness training program is designed is the basis of periodization. This period, whether it is a four years, a year, or less, should be divided into shorter periods, which make up the principal time frames referenced for various stages of training and progress toward goals. The shorter time frames are called cycles. For instance, in training for a college level football program, the main period of interest is four years, macrocycles. Each year of the four year period is considered to be a sub training cycle, mesocycles, which can be further divided into multi-week cycles, microcycles (3, 6, or 8 to 16 weeks). Thus, a college career for a football player may be four or five years (macrocycle), which is comprised of four or five cycles (mesocycle), each of which is a one year in length and is divided into shorter cycles of training of 3, 6, or 8 to 16 weeks (microcycle). A strategy for remembering the order of the three divisions of training is to associate the order, alphabetically, with the second letter. As an athlete moves through the various cycles of training, his or her ability to produce and use energy should increase and subsequently his or her level of performance should improve. The ideal effect is that athletes will perform at higher levels, as time passes (the principle of progressive overload)
Periodization provides a foundation for goal setting that makes planning fitness programs more meaningful and realistic Thus, it makes successful planning and management of fitness training programs, based on the level of energy production, more successful. Periodization should, indeed, be considered an essential part of one's ability to manage his or her production of energy to achieve higher levels of fitness.
The principle of progressive overload
When the amount of activity is gradually increased from short to long periods of time and increased in intensity both, flexibility and cardio respiratory endurance, as well as all of the other components of fitness, can be improved. The more intense an athlete can exercise comfortably, the greater his or her improvements will be. "It is what an athlete does that makes a difference, not what he or she almost does." When athletes lessen their participation in sports, utilize less energy, and become older, the range of motion in their joints (flexibility) and the ability of their bodies to utilize oxygen (cardio respiratory endurance) to produce energy decreases, drastically. Unless careful attention is given to these components with a fitness maintenance program, all that was gained through training will gradually be lost (the principle of reversibility).
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It is important to understand
the functions of the cardio respiratory system in order to understand how it
responds to endurance or aerobic fitness activities. Such knowledge requires an
understanding of the structure of the heart, blood flow through pulmonary and
systemic circulation, and how and where oxygen must be extracted from the blood
to be used in the synthesis of ATP or to produce aerobic energy.
The study of fitness improvement involves the study of several concepts related to energy. Three questions that contribute to the knowledge needed about energy and athletic performance are as follow: "What is energy? How is energy produced?" and "How does energy affect performance?" Knowledge of these concepts leads to an understanding of energy formation, use, and transformation with the principle concept the synthesis and resynthesis of ATP.
There are three ATP energy systems: the creatine phosphate system (ATP-CP system), the anaerobic glycolysis system (lactic acid system), and the oxygen system (aerobic system). Both the ATP-CP and lactic acid systems are anaerobic, results from chemical activity that produces ATP for muscle contraction, which does not require oxygen. The oxygen system is aerobic, which means that oxygen is required for the chemical activity responsible for producing ATP.
The balancing of all metabolic or chemical activities in the body is referred to as homeostasis. Homeostasis is the continuous interaction of cellular physiology to achieve smooth operation of thousands of body functions. Physical or fitness activities also stimulate metabolic changes in the body to ensure balance. Activities can be selected with respect to the components of fitness to effectuate specific changes to improve performance in athletics.
There are three important phases of athletic training sessions, warm-up, workout, and cool down. When physical activities are manage for these three periods of a training session are honored, the desired training effect can be accomplished and the risk of injury or other ill effects of training can be reduced. All training sessions should be planned with respect to periodization, which is the division of a greater period of time into smaller training periods. The longest period of training referenced is known as the macrocycle; this period is divided into shorter periods of training called mesocycles, which is divided into even shorter periods of training called microcycles.
When energy is produced, it becomes apparent that it increases according to the level of intensity, which are due to the bodily effects that make the rate of exertion perceivable. Strategies that can facilitate the control of frequency, intensity, and duration of exercise is essential for continuous progress toward goals. The use of these and other principles improves the ability of athletes to reach their goals.
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Marieb, Elaine N (1992). Human Anatomy and Physiology. Benjamin/Cummings Publishing, Inc., Redwood City, CA
McArdle, W. D., Katch, F. I.., and Katch, V. L (1991). Exercise Physiology: Energy, Nutrition, and Human Performance. Lea & Febiger, Malvern, PA.
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