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Exercise
Physiology
There
are primarily three energy systems in the human responsible for
the production of fuel for your muscles. Learning about these
energy systems gives you a more complete and overall picture of
what is happening to your body when you exercise. This knowledge
will also enable you to differentiate between different exercises
to achieve a particular goal or maximize physiological adaptation.
A person's ability to perform an activity is based on the ability
to gain required energy. Energy requirements may be short term
or long term depending on the activity. Long-term performance,
usually requires a great deal of energy from aerobic (meaning
utilizing oxygen) sources. Those who train to enhance their endurance
or cardiovascular system will train aerobically. In contrast,
short-term performance requires its greatest energy from anaerobic
sources (meaning without utilizing oxygen) and is thus referred
to as anaerobic activity or training. There is a variety of different
training modes for anaerobic exercise including everything from
weight training to sprinting, all of which do not use oxygen as
a limiting factor in performance.
ATP
(adenosine triphosphate) serves as the energy currency for all
cells, however, its quantity is limited. Thus, ATP must be continuously
resynthesized to continuously supply energy for biological work.
Although anaerobic and aerobic exercises ultimately provide the
same resulting energy (ATP) to working muscles, their delivery
and mechanisms vary greatly. Let us examine these energy systems
more thoroughly.
There
are two types of anaerobic energy sources, the phosphogen system
and glycolysis. The phosphagen system provides ATP immediately
to the muscle, so the energy needs of fast and powerful movement
are met in the immediate area of the muscle's contractile machinery.
This type of energy is vital for sports of very intense and short
duration, such as sprinting, power lifting, wrestling, football,
etc. The ATP generated lasts less than 10 seconds.
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Sprinters
utilize the phosphagen system for 6-10 seconds for explosive
energy and high power output producing more work in a shorter
period of time. |
Glycolysis
is the breakdown of glucose to pyruvic acid and the conversion of
this intermediate, in the absence of oxygen, to lactic acid. The
primary food source of glucose for the body is carbohydrates. This
reaction needed to break down the glucose creates a greater time
delay in energy production compared to the phosphagen system. Sports
such as boxing and basketball use a relatively high ratio the glycolytic
system. After 20 to 30 seconds, the anaerobic contributions to delivery
ATP decrease and aerobic pathways steadily increase.
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Gymnasts
typically rely heavily on anaerobic glycolysis for increased
performance usually lasting less than 1 minute. |
Aerobic or endurance training has a direct physiological adaptation
associated with increased oxygen uptake and cardiac output. Metabolic
changes include an elevated respiratory capacity, lower blood lactate
leves, increased mitochondrial density and improved enzyme activity.
Aerobic athletes are able to show progressive improvement in their
abilities to extract and utilize oxygen. Aerobic training may also
change and alter body composition by decreasing relative percentage
body fat and has little or no significant effect on fat free mass.
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Marathoners
use the aerobic energy system to provide the maximum energy
release over extend time periods. |
For combinations
of energy systems used in various sports, please review the following
chart:
Reference
Source 28,29,31,63,82
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