Anaerobic Energy System
Anaerobic
Energy Systems
• 2 Types:
- ATP-PC <8 sec
- Lactic Acid OR Anaerobic Glycolysis
Page 57 of Lab
Manual
<3min
ATP-PC energy source is
Creatine Phosphate
Lactic Acid System uses
glucose (sugar) for its energy
By Jake and Charlotte
ATP-PC Energy System
• least complicated
• provides energy for activities of short duration (up to 10 seconds)
and high intensity (85-100% of maximal effort)
• most evident in events such as 100m sprints, swimming, high jump
• without this system fast powerful movements would not be able to
be performed
Lactic Acid System
(Anaerobic Glycolysis)
• Its more complicated than the ATP-PC system
• far more powerful, providing energy for events of up to
three minutes (400m, 800m)
• uses carbohydrates as its main fuel for rebuilding ATP
Definitions
Anaerobic Energy System
Highlight the ATP-PC System and Lactic Acid System
• Speed: The ability of the body, or part of the body, to move as
quickly as possible from one place to another
• Power: combination of speed and strength
• Work: Force expressed through distance, or a displacement,
independent of time
• Velocity:
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EPOC
Sources of Fatigue
Excess Postexercise Oxygen Consumption:- elevated oxygen consumption
above resting levels after exercise; at one time referred to as oxygen debt.
•
Example:
Running up a few flights of stairs in the education building to get to a class
on time. This leaves you with a rapid heart rate and feeling short of breath.
After a few minutes your pulse and breathing returns to normal. This is a
great example of excess postexercise oxygen consumption at work in
everyday life.
FATIGUE
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We typically use the term fatigue to describe general sensations of
tiredness and accompanying decrements in muscular performance. Most of
the underlying causes of fatigue focuses on:
the energy systems (ATP-PCr, anaerobic glycolysis & oxidation)
the accumulation of metabolic by-products, such as lactate
the nervous system
failure of the muscle fiber’s contractile mechanism
However, none of these alone can explain all aspects of fatigue, and other
factors such as stress or environment are thought to contribute to fatigue.
Many questions about fatigue remain unanswered!
PCr DEPLETION
• PCr (phosphocreatine) is an energy rich compound that plays a
critical role in providing energy for muscle action by maintainig ATP
concentration.
• PCr is used under anaerobic conditions to rebuild high-energy ATP
as it is used.
• As PCr is depleted, your body's ability to quickly replace the spent
ATP is hindered.
• ATP use continues but the ATP-PCr system is less able to replace
it, therefore ATP levels are also decreased.
• It now appears that P is a potential cause of fatigue.
NEUROMUSCULAR
FATIGUE (NERVE
IMPULSE)
• Evidence suggests that under some circumstances, fatigue may
result from an inability to activate the muscle fibres, a function of the
nervous system.
• Nerve impulses are transmitted across the neuromuscular junction
to activate the fibre's membrane, and it causes the fibre's
sarcoplasmic reticulum to release calcium. The calcium in turn,
binds with troponin to iniate muscle contarction.
• Evidence suggests that fatigue maybe attreibuted to calcium
retention within the sarcoplasmic reticulum, whihc would decrease
the calcium available for muscle contraction.
• Depletion of PCr and build-up of lactate might simple increase the
rate of calcuim accumulation with the sarcoplasmic reticulum.
• Remains speculative!
MUSCLE GLYCOGEN
DEPLETION
• Muscle ATP levels are also maintained by the aerobic and
anaerobic breakdown of muscle glycogen.
• In events lasting only a few seconds (eg.sprints), muscle glycogen
becomes the primary energy source for ATP synthesis.
• The muscle depends on a constant supply of glyocgen to meet the
high energy demands of exercise. However, glycogen reserves are
limited and are depleted quickly.
CENTRAL NERVOUS
SYSTEM (CNS MUSCLE
RECRUITMENT)
• Early studies showed that when a subject's muscles appeared to be
nearly exhausted, verbal encouragement, shouting or even direct
electrical stimulation of the muscle could increase the strength of
muscle contraction.
• These studies suggest that the limits of performance in exhaustive
exercise may, to a great extent, be psychological.
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METABOLIC BYPRODUCTS
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Sprints in running, cycling or swimming all lead to large accumulations of
lactic acid. However, the presence of lactic acid shouldn't be blamed for the
feeling of fatigue itself.
When not cleared, the lactic acid dissociates, converting to lactate and
causing an accumulation of hydrogen ions.
This H+ accumulation causes muscle acidification, resulting in a condition
known as acidosis.
Activities of short duration and high intensity, such as sprinting, depend
heavily on anaerobic glycolysis and produce large amounts of lactate and
H+ within the muscles.
Luckily, the cells and body fluids possess buffers, such as bicarbonate
(HCO3), that minimalise disrupting influence of the H+.
Without these buffers, H+ would lower the pH to about 1.5, killing the cells.
Because of buffering, the H+ concentration remains low even during severe
exercise, allowing muscle pH to decrease from a resting value of 7.1 to no
lower than 6.6 to 6.4 at exhaustion.
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