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Introduction
Louis Pasteur is considered a father of the scientific
study of glycolysis. This process was first studied through fermentation,
which occurs as yeast carries glycolysis extra steps to produce ethyl
alchohol, C02, and vinegar. This scientist also found a technique that
prevented table wine from going the extra steps mentioned. This process is
known as pasteurization. Further, Pasteur analyzed glycolysis in yeast and
in other single celled organisms in which 02 was removed, or present. He
noted that when 02 was included glycolysis occurred at a slower rate and
resulted in less lactate accumulation. However, when it was not included
glycolysis, it was rapid and lactate accumulated. As will be seen in part
three of this series, these slow and rapid velocities have much importance
in exercise science. Pasteur is also famous for discovering a vaccine for
rabies. Moreover, in 1888, the Pasteur Institute
was established in
Paris
to continue the fight against diseases.
A further subject
studied by this giant was Biogenesis.
Biogenesis explains that living things can be produced only by other
living things.
Abiogenesis is the supposed transformation of inanimate matter into living
matter; also know as spontaneous generation. Spontaneous generation has
never been observed. This has been seen so consistently that it is called
the law of biogenesis, which states that life comes only from life, a
fundamental law of biology. Louis Agassiz and Louis Pasteur scientifically
developed this law in the 1850s, yet science textbooks today still state
that abiogenesis happened. Dr Jonathan D. Sarfati (2004) states:
So far, there has not been a single observed exception to
the Law of Biogenesis, so it truly stands as a scientific law.
Nevertheless, billions of schoolchildren who are taught this law are also
taught that 'once upon a time, perhaps in a galaxy far, far away', there
was an exception, and possibly many more.
It
should be realized that textbooks do take a while to get up to date. But
150 + years are long enough to correct this error.
Professor Dr. Klaus, in “The Origin of Life; More Questions than Answers,”
states (p. 348):
More than 30 years of experimentation on the origin of life in the fields
of chemical and molecular evolution have led to a better perception of the
immensity of the problem of the origin of life on earth rather than to its
solution. At present all discussions on principal theories and experiments
in the field either end in stalemate or in a confession of ignorance.
Simply put, to believe in abiogenesis goes against all logic and
scientific support. George Wald, famous for being one of the founders of
the Neo Darwinian Religion, states:
One has only to contemplate the magnitude of this task to
concede that the spontaneous generation of a living organism is
impossible. Yet here we are as a result, I believe, of spontaneous
generation.
The present writers wholly agree with the impossibility aspect. Moreover,
British scientist Sir Fred Hoyle (1981), who won
the Nobel Prize for astronomy, can also sympathize. This great scientist
calculated the probability of just one functioning protein molecule
originating from nothing as being equivalent to filling the entire solar
system with blind men holding Rubik’s cubes, and for each of them to get
the right solution at the exact same time! Now if someone would like to
believe in spontaneous generation, that is fine. But just understand that
this belief goes against all logic, and takes complete blind faith to
trust in. However, it would behoove the reader to instead put their trust
in the way, the truth, and the life—Jesus Christ.
Jeremiah 17:5-8
5 Thus saith the LORD; Cursed be the man that
trusteth in man, and maketh flesh his arm, and whose heart departeth from
the LORD. 6 For he shall be like the heath in the desert, and shall not
see when good cometh; but shall inhabit the parched places in the
wilderness, in a salt land and not inhabited. 7 Blessed is the man that
trusteth in the LORD, and whose hope the LORD is. 8 For he shall be as a
tree planted by the waters, and that spreadeth out her roots by the river,
and shall not see when heat cometh, but her leaf shall be green; and shall
not be careful in the year of drought, neither shall cease from yielding
fruit. The heart is deceitful above all things, and desperately wicked:
who can know it?
The Phosphagen System
The immediate source of energy in the body comes from three interrelated
components (Brooks et al., 2000). Generally, three ounces of adenosine
triphosphate (ATP) are stored and broken down by ATPases when needed for
an immediate supply of energy. Further, the amount of free energy from ATP
hydrolysis is estimated to be –11 kcal.mol-1.This phase is quite short,
lasting only 1-2 seconds. The byproducts of ATP are adenosine diphosphate
(ADP) and inorganic phosphate (Pi). The former molecule is
rephosphorylated (has a phosphate attached) by the high-energy compound
creatine phosphate (CP). This is the second immediate source of energy.
Catalyzed by the enzyme creatine kinase, the inorganic phosphate of CP is
transferred to the ADP molecule, forming ATP. CP is more prevalent in
muscle cells than ATP—approximately six times the amount. Here is a visual
analysis of this reaction:
Createine
CP
+ ADP à
ATP + C
Kinase
This newly formed molecule of ATP can now be hydrolyzed for another rapid
source of energy while CP is rephosphorylated by mitochondrial creatine
kinase.
Lastly, two molecules of ADP can be used to generate ATP. The enzyme
adenylate kinase, also known as myokinase in muscle cells, takes two ADP
molecules to form ATP; one is dephosphorylated, and the other is
phosphorylated by the removed phosphate of the former molecule, resulting
in one molecule of ATP and one molecule of Adenosine monophosphate (AMP).
Here is an illustration:
Adenylate
ADP + ADP
à
ATP + AMP
Kinase
In
total, this energy system can be maximally sustained for 5-15 seconds.
The Creatine Phosphate shuttle
Adenosine Triphosphate is a very volatile substance. Therefore a problem
in exercise physiology was finding how it was transferred from the
mitochondria to region of the myofibrils to provide for the initiation of
contraction. Enter the Creatine Phosphate Shuttle mechanism. The system
can be described as follows (Bessman, 1987):
1. ADP is rephosphorylated by creatine phosphate in the cytoplasm.
2. The free creatine is then rephosphorylated at the inner mitochondrial
membrane from ATP that was produced by the electron transport chain.
3. The ADP is then rephosphorylated by Oxidative phosphorylation (ETC).
4. Process continues until ATP and CP stores are filled.
5. Creatine Kinase is responsible for the phosphorylation process.
Glycolysis
Glycolysis can be defined as the dissolution of sugar (Plowman & Smith,
2001). More specifically, it is a concept representing the energy pathway
in which the catabolism of glucose in a 10 or 11 step process yields the
products pyruvate (10 steps) or lactate (11 steps). The subsequent
analysis will focus on the ever-constant molecules present in anaerobic
energy production. It should be noted, however, that several molecules can
be converted into substrates (a substrate is any molecule acted upon by an
enzyme) utilized during glycolysis.
Energy is directly available from glycolysis via substrate-level
phosphorylation. That is, the transfer of an inorganic phosphate (Pi)
directly from a phosphylated intermediate. If glucose is utilized, a net
total of two ATP molecules are produced; if glycogen, 3 molecules.
Each step is catalyzed by enzymes. For glycolysis to occur in the
musculature, glucose must first be absorbed, and transported into the
muscle cell. This then crosses the cell membrane by facilitated diffusion.
With the help of a protein carrier; this transpires by a concentration
gradient; as such, the transport is by passive systems, and energy is not
required. For more information on transport systems, refer to Venom (2003.
Sodium - A comprehensive Analysis.)
The protein carrier utilized is either GLUT-1 (non-insulin-regulated) or
GLUT-4 (insulin-dependent). When blood glucose levels are stable, most
glucose enters the cell by GLUT-1 receptors; and contrarily, when insulin
is high it enters primarily by GLUT-4 receptors (Wilson, 2003 Pre Contest
Preparation Analysis) as well as exercising activities. It is postulated
that calcium is a secondary messenger to insulin, which causes activation
of GLUT-4 receptors during exercise (Wilson, 2003).
The location of glycolysis is in the cytosol, with the
exception of a few glycolytic enzymes such as Lactate dehydrogenase, which
exist in organelles such as the mitochondria. Moreover, the process is
entirely anaerobic (occurs without utilizing oxygen). For a review of the
cell cytoplasm, see
Wilson
(2002,
The Anatomy of A Muscle.)
Additionally, 4 hydrogen atoms are carried of by 2 NAD coenzymes, and
potentially taken to the electron transport system for oxidative
phosphorylation. Pyruvate, the final product of glycolysis, may also be
converted to acetyl coenzyme A, and enter the Tricarboxylic Acid cycle,
sustaining the process of cellular respiration.
Glycolysis is said to be controlled primarily by feed forward and feedback
controls (Brooks, 2000). Feed forward control factors include stimulation
of glucose uptake (i.e. muscular contraction) and glycogenolysis (by
epinephrine and contractions). These factors speed glycolysis. Feedback
controls refer to changes in levels of metabolites by glycolysis, such as
a decline in blood glucose at the end of exercise. These can either speed
or slow glycolysis.
Lastly, glycolysis is an exergonic reaction.
The following is a comprehensive 11-step analysis of glycolysis, after
glucose or glycogen has entered the cytoplasm of the cell (Brooks, 2000;
Plowman & Smith, 2001; Marieb 2001; and Frissel, 1982).
Step 1:
To
begin, glucose is phosphorylated by the rate limiting enzyme hexokinase.
In the process, adenosine triphosphate (ATP) is de-phosphorylated. This
phosphate is then transferred to the sixth carbon of glucose, resulting in
glucose-6-phosphate.
If
your body instead utilizes glycogen, glycogenolysis occurs; either way,
the same product—glucose-6-phosphate—is produced. In this event, the rate
limiting enzyme glycogen phosphorylase degrades glycogen into the molecule
glucose-1-phosphate, the enzyme phosphoglucomutase, and then transfers the
phosphate bond from the first carbon of glucose to the sixth, forming
glucose-6-phosophate. The advantage to using glycogen is ATP hydrolysis is
not required, effectively sparing energy.
In
review, phosphorylation refers to the addition of a phosphate group to a
molecule. De-phosphorylation is the exact opposite; a phosphate group is
removed from a molecule. Moreover, a rate limiting enzyme literally
regulates the speed of a process. As the activity of these enzymes
increases, the product increases; likewise, as the activity of these
enzymes decreases, the rate of the process decreases.
In
muscle cells, the electrical charge added to glucose (or glycogen) by
phosphorylation traps the molecule within the cell. The reasons for this
are twofold: first, the cell membrane is non-polar (has no charge),
thereby prohibiting the charged glucose molecule from crossing the cell
member, as the cell lacks transport mechanisms for phosphorylated
molecules; secondly, the enzyme which is able to separate this bond does
not exist in muscle cells. In the liver, however, (and to some extent, in
the kidneys) the enzyme phosphatase is present and able to readily split
the glucose-phosphate bond. Subsequently, glucose is de-phosphorylated; it
may now leave the cell and enter the blood stream, where it is partitioned
by the body to various sites.
This information is vital for the athlete. That is, glycogen depletion and
supercompensation are specific to individual muscle groups. Moreover, in
order for glycogen to be utilized during exercise, it must be already
present within the muscle cell. It follows that depleting muscle glycogen
stores must be done by training the specific muscle group. This is
especially significant when considering that glycogenolysis (the
catabolism of glycogen) is the preferred energy source for glycolysis
during exercise.
Step 2:
Glucose-6-phosphate is now rearranged to form fructose-6-phosphate. The
enzyme that catalyzes this reaction is called phosphoglucose isomerase.
Throughout this entry the reader will view the term, “isomer”. An isomer
refers to two or more molecules that have the same chemical formula but
different atomic arrangements. Enzymes, which catalyze these structural
changes, are known as isomerases.
Step 3:
Fructose-6-phosphate is phosphorylated on the first carbon of the hexagon
molecule, forming fructose 1, 6-diphosphate. The enzyme that catalyzes
this is phospho-fructokinase (PFK). Consequently, this is the most
essential rate-limiting enzyme in glycolysis. During this procedure,
another ATP molecule is de-phosphorylated. To clarify the name of this new
molecule, “1, 6” stands for the phosphate bonds attached to the first and
sixth carbon of the fructose molecule; “di,” meaning two, refers to there
being 2 phosphate bonds.
Step 4:
The following event is the namesake of glycolysis, for here, sugar
splitting—the meaning of the term “glycolysis”—transpires. Directed by the
enzyme aldolase, the 6 carbon molecule, fructose 1,6 diphosphate, is split
into 2, 3-carbon sugar molecules. While having identical component atoms,
this duo differs in atomic arrangement; hence, two different names are
given, these being dihydroxyacetone phosphate (DHAP) and glyceraldehyde
3-phosphate (G3P).
Step 5:
Here the enzyme Triose Phosphate Isomerase rearranges DHAP to form G3P.
Note:
From this point on, every reaction occurs twice.
However, they will only be listed once (with reminders given
throughout); keep this in mind when calculating the following reactions.
Step 6:
Two conditional reactions occur next. First, G3P is oxidized by the
hydrogen carrier nicotinamide adenine dinucleotide (NAD). NAD is
subsequently reduced to NADH + H+. Following the energy released from the
reaction, a second event results. The now oxidized form of G3P is
phosphorylated on the first carbon by an inorganic phosphate—ever present
in the cytoplasm—forming 1, 3-disphosphoglycerate. As noted above, this
reaction occurs twice. And lastly, this reaction is catalyzed by
Glyceraldehyde-3-Phosphate Dehydrogenase.
Venom (2003) explains the hydrogen carrier Nad as follows:
Niacin, also known as nicotinic acid nicotinamide and
vitamin b 3, is a water-soluble vitamin, and a part of the b-complex.
Digestion
In the human body, niacin is broken down to Nicotinamide
adenine dinucleotide phosphate (NADP), and nicotinamide adenine
dinucleotide (NAD). These are the primary forms which niacin functions
within the body…
Function
Almost 200 enzymes require NAD and NADP to function. To
name a few B3 functions, NAD helps glycolysis, oxidation of pyruvate,
acetyl CoA by the kreb cycle, and fatty acids. NADP assists with fatty
acid synthesis, cholesterols and steroid synthesis, oxidation of
glutamate, and DNA synthesis. Some enzymes which require NADP are
glutathione reductase, dihydrofolate, and tetrahydrofolate [107,56,43,33].
NAD+ is a prime hydrogen carrier in glycolysis. This derivative of Niacin
can accept two electrons and protons from two hydrogen atoms. It is
composed of the nucleotides adenine and nicotinamide.
The term “oxidation” means the loss of electron atoms. “Reduction”
describes a gain of electrons atoms.
Therefore, in the step 5, G3P is oxidized (loses electrons), while NAD is
reduced (gains electrons.
It
may seem odd that the term reduction is used, but think of it this way:
electrons have a negative charge; therefore, by gaining electrons, the
molecule effectively reduces its charge.
The final destination for the hydrogen atoms taken by NAD is the electron
transport system, where oxidative phosphoryalation takes place. Here, a
multitude of ATP molecules are produced. This vital step of cellular
respiration will be discussed in future entries. If the reduced form of
NAD is unable to enter the electron transport chain, the result is pyruvic
acid, which forms lactic acid.
NAD is often referred to as a taxi cab. It “picks up” hydrogen atoms
(passengers; resulting in reduction) from one point, and drops them off
(as a taxi cab would; resulting in oxidation) at another, without either
participant being permanently changed.
Step 7:
Finally, the high-energy molecule ATP is formed! 1, 3-disphosphoglycerate
is de-phosphorylated on the first carbon-phosphate bond by the enzyme
Phosphoglycerate Kinase. This phosphate is transferred to an ADP molecule,
resulting in ATP. Once again, this reaction occurs twice.
Step 8:
3-phosphoglycerate, the resulting product from the previous
step, is rearranged to form 2 phosphoglycerate (G2P). Here the phosphate
group is simply transferred from the third carbon to the second. This is
catalyzed by phosphoglycerate mutase.
Step 9:
Catalyzed by the enzyme enolase, a water molecule is now
removed, resulting in phosphoenolpyruvate. This causes the bond between
the phosphate group and the remaining atoms in the molecule to be
weakened.
Step 10:
The lone phosphate group is now transferred from
phosphoenolpyruvate to an ADP molecule by the rate limiting enzyme
pyruvate kinase. The end products are pyruvate and ATP.
Step 11:
Referring back to step six, if the hydrogen atoms picked up
by NAD are not able to participate in oxidative phosphorylation, they are
instead transferred to pyruvic acid (produced in step 10), resulting in
the formation of lactic acid.
Now, glucose, the first molecule in this process, has a
chemical formula of C6H1206, while
pyruvic acid has the structure 2C3H403.
The amount of oxygen and hydrogen atoms in these molecules is equivalent;
however, pyruvic acid contains two less hydrogen atoms. These are the same
atoms that NAD picks up in step six. If lactic acid is formed, then the
result is 2C3H6O3; all original atoms are now accounted for. Additionally,
both pyruvic and lactic acid contain carboxyl groups, that is, one of the
oxygens is double-bonded to a carbon atom; another oxygen molecule is
single bonded to the carbon on one side, and single bonded to the hydrogen
on the other; and the remaining bond on the carbon atom is attached to the
rest of the molecule.
This is a reversible reaction, which means that lactate can
be reconverted to pyruvate. The enzyme which catalyzes step 11 is called
lactate dehydrogenase, which is a vital rate limiting enzyme, discussed
profoundly further on in this entry, in addition to the final destination
of lactic acid.
Lastly, pyruvate can be used for the formation of acetyl
coenzyme A, which then enters the Krebs Cycle.
Control of Glycolysis
As previously discussed, feedback and feed forward control
systems primarily regulate the rate at which glycolysis runs. This next
section will be comprehensive analysis of several of these elements
(Brooks, 2000).
Phosphofructokinase
PFK is the most essential rate-limiting enzyme in
glycolysis; this falls under the category of feedback control. PFK is a
multivalent, allosteric enzyme, which means that numerous metabolites can
bind to it and influence its catalytic capacity. High levels of ATP, CP,
and citrate slow PFK activity. Citrate is the first product in the
Tricarboxylic Acid Cycle (also known as Krebs and citric acid cycle). It
therefore follows that aerobic metabolism can lower anaerobic metabolism
from the formation of citrate. These modulators are high during rest;
however, when exercise starts their activity subsequently decreases,
promoting the activation of PFK. Some stimulators of PKF are ADP, AMP, Pi,
and elevated Ph and ammonia.
Glycogenolysis
At rest, glycogen catabolism is minimized; contrary to
this, anabolism is often prevalent. As such, during rest glycolysis
utilizes glucose at a heightened extent. During exercise, however, this is
not the case. Glycogen catabolism is immensely accelerated during physical
events, and subsequently becomes the dominant source of fuel for
glycolysis. In fact, during steady exercise at 65% VO2 max, glycogenolysis
can surpass muscular glucose absorption by 5 times. This again solidifies
the importance of having high glycogen stores to maximize exercise
performance. Incidentally, glycogen depletion results in extreme muscular
fatigue (Wilson, 2003 Precontest Preporatory Strategies).
Lactate Dehydrogenase
LDH is the rate-limiting enzyme responsible for the
production of lactic acid from pyruvic acid. The rate of lactic acid
production is highly dependent on this enzyme, and its respective
isoenzymes. This enzyme and its regulation are discussed in-depth further
on.
Pyruvate Dehydrogenase
Along with the aforementioned rate-limiting enzyme, this
will be discussed thoroughly later in this entry.
Hexokinase & Pyruvate Kinase
Hexokinase is the first rate-limiting enzyme in glycolysis,
and is responsible for the phosphorylation of glucose into
glucose-6-phosphate. Consequently, its rate is inhibited by the production
of the later molecule, but enhanced by the former. Pyruvate Kinase is
responsible for the production of pyruvate and ATP in step 10. Its rate is
inhibited by ATP and CP, and increased by the production of
phosphoenolpyruvate.
Efficiency of Glycolysis
Many falsely claim that glycolysis is an “inefficient”
energy pathway, as only 2-3 molecules of ATP are generated. However, this
could not be farther from the truth. Glycolysis is in fact very
efficient.
The energy transformation (from
glucose to lactate is -47kcal.mol-1. The amount of free energyG) produced from glycolysis is 11 kcal.mol-1 of ATP. When 2 ATPs are
formed, calculations find that:
Efficiency = 2 * -11 = .47 * 100= 47%
-47
20% efficiency is considered incredible. Glycolysis has
nearly 50% efficiency! This is a great amount of energy conserved. Indeed,
glycolysis is a very efficient pathway.
The Time Energy System Continuum
The manufacture and utilization of ATP occurs through three
energy systems: the phosphagen system (ATP-PC), glycolysis, and the
oxidative system. The sequence at which these energy systems are recruited
is known as the “Time Energy Continuum” (Plowman & Smith, 2001). The
following section will analyze which systems predominates in a given
event; particular emphasis will be placed on anaerobic metabolism.
The first two energy systems discussed—ATP-PC and
glycolysis—are known as anaerobic systems, as they do not utilize oxygen.
Conversely, the oxidative system does utilize oxygen, and is therefore
termed aerobic. When the phrases “aerobic” and “anaerobic” exercise are
used, they refer to which energy systems dominates, not which one
exclusively is utilized, as all 3 are used for all exercise modalities.
The anaerobic systems are delineated by lactic acid
production. The ATP-PC system does not produce lactic acid, while
glycolysis does. As such, these pathways are referred to as alactic and
lactic anaerobic, respectively.
In addition to these energy pathways, the body stores a
small amount of ATP, which can be used for 1-2 seconds of maximal work.
Afterwards, the byproduct ADP can be instantaneously phosphorylated by
phosphocreatine, effectively reforming ATP. There is roughly triple the
amount of PC than ATP in the muscle. Stored ATP is utilized whenever
energy demands increase. Be it typewriting, turning a page, or lifting a
weight, a portion of the energy provided will be from this stored form of
ATP, which subsequently is replenished. This system predominates for
approximately 10 seconds of all out exercise, after which glycolysis
begins to dominate.
When the need for ATP surpasses the capacity of alactic
anaerobic metabolism and the aeorobic system, glycolysis becomes the
dominant energy supplier. Together, anaerobic metabolism is chiefly
utilized for exercise lasting less than 2 minutes.
After 5 minutes of exercise, the oxidative
system—consisting of the Krebs cycle and oxidative phosphorylation—becomes
dominate. The longer exercise lasts, the more this system is utilized.
Astrand and Rodhal (1977) and Gollnick and Hermansen
(1973) have reviewed the time energy continuum at various intensities.
Evidence indicates that in the first 10 seconds, the phosphocreatine
system is dominant; at 30 seconds, anaerobic metabolism is called upon for
80% of the energy requirements, but glycolysis is now much more prevalent.
At this point, 33% of the energy is supplied by the alactic anaerobic
system and 47% by glycolysis. At one minute, glycolysis is used at a
slightly heightened extent, as well as aerobic metabolism, while the
ATP-PC system continues to decrease. At five minutes, aeorobic metabolism
dominates as much as aneorobic metabolism did at 30 seconds. Now, 80% of
the energy utilized is from aerobic work, and approximately 20% is from
anaerobic metabolism; 3, and 17% coming from phosphocreatine and
glycolysis, respectively. The longer exercise continues the more aerobic
metabolism is called upon. It should be noted that these results can and
do vary among individuals; however, this is generally an accurate account.
Ergogenic Aid
Supplementation with creatine can change the time energy
continuum so that the ATP-PC system is predominantly relied upon for an
extended period of time, effectively enhancing athletic performance. For
more on the benefits of creatine, refer to
Wilson (2001,
Creatine Myths And Facts. )
Anaerobic Metabolism
No sufficient procedure exists to directly measure the
amount of energy anaerobic metabolism contributes to exercise. Two
indirect approaches exist, however. The first estimates how much work was
done, or the power produced during a short duration, high intensity
activity. The second monitors changes in chemical substances which are
produced by glycolysis (lactic acid) and alactic anaerobic metabolism (ATP
and PC levels).
Analyzing PC and Lactate levels
The most often used measure of blood lactate levels is
taking a blood sample of the participant. This is done by either
venipuncture (the puncture of a vein with the purpose of obtaining a blood
sample) or finger prick. This method is very cheap, as well as accurate,
and easy to use; thus, it is quite popular.
The reason blood tests are used is that lactic acid (2C3H6O)
at normal pH values dissociates in the blood stream into hydrogen ions and
lactate (C3H503-). Though lactate and lactic acid are different compounds,
they are often used interchangeably. Properly though, lactate is the salt
of the acid. Consequently, the same logic applies to pyruvic acid, which
is also used interchangeably with its respective salt pyruvate (Brooks,
1985).
From here, lactate values are measured from blood samples.
It’s important to note that it takes a bit for lactate to reach the blood
stream from the muscle cell (approximately 5-10 minutes). Therefore,
highest levels of lactate must be viewed within several minutes into
recovery, rather than during exercise.
The measurement for lactate is usually measured by
millimoles per liter. Resting levels of lactate are around 1-2 mmol.L.
Eight mmol.L-1 usually represents the maximum work of an individual.
However, values up to 32 mmol.L have been reported.
Muscle biopsy (a procedure in which a small amount of
muscle is removed for an analysis) is also used to measure ATP-PC and
lactae values, but this is a more complicated and costly procedure, and
therefore not used as often.
Anaerobic Power and Capacity
When speaking of energy systems, the term “capacity” means
the total amount of energy which can be produced by a particular energy
pathway. While “power” refers to the maximal amount of energy that can be
produced per unit of time. The rank of power from high to low is: ATP-PC,
glycolysis, and aerobic. The system with the most capacity, accordingly,
is the exact opposite: aerobic, glycolysis, and ATP-PC.
The following is a chart of the capacity and power of the
three energy systems in untrained individuals (Bouchard, Taylor, & Dulac,
1991):
Table 1 Time
Energy System Continuum Power and Capacity
|
|
Energy Pathway |
Capacity |
Power |
Time |
|
|
Kcal |
Kcal.min-1 |
Hr:min:sec |
|
Aerobic System |
359-1268 |
7-19 |
2:21:0 |
|
ATP-PC |
11 |
72 |
0:0:10 |
|
Glycolysis |
48 |
36 |
0:1:20 |
Table 1 illustrates the ATP-PC system has a high power
ranking of 72 kcal per minute. However, it can only sustain this for
approximately 9-10 seconds, resulting in a capacity of only 11 kcal. This
is calculated by dividing 72 (power) by the time span (one minute)
resulting in 1.2 kcal per second. Further dividing 11 (capacity) by 1.2
gets the result 9.17 seconds, or 11kcal produced in 9-10 seconds.
Glycolysis has less power, but more capacity than the
alactic acid system. In total, it can manufacture 36 kcal per minute; but,
it can maintain this power for 1 minute, and 20 seconds, resulting in 48
kcals.
The aerobic system has the lowest power at 7-19 kcal per
minute, but by far the highest capacity. When using only carbohydrates,
the oxygen system can maintain its power for 2 hours, resulting in
360-1268 kcals. When all fuels are taken into account, this system can
potentially last for hours on end.
Measuring Anaerobic Pathways
As stated previously, no experiment exists that can
directly measure power and capacity. Instead, indirect tests are performed
by 3 means:
-
The time required to
perform a given amount of anaerobic work.
-
The total mechanical
power produced during high intensity, short duration work.
-
The amount of
mechanical work done in an allotted period of time.
Two commonly used tests are the Maragariat-Kalamen Stair
Climb, field tests, and the Wingate Anaerobic Test (WAT) (Bouchard, et
al., 1982)
Note:
The following section will continue various calculations;
whenever you see a “.” between numbers, this represents
per unit of time.
Maragariat-Kalamen Stair Climb
Lasting for approximately five seconds, the
Maragariat-Kalamen Stair Climb is a short, explosive test used primarily
to test the ATP-PC system (Bouchard, et al., 1982).
To perform this test, the participant runs for 6 meters on
level ground, and then climbs a staircase, taking three steps each time.
Power is calculated by kilogram-meters per sec using measurements of the
subjects’ weight, vertical height between the third and ninth steps, and
the amount of time it takes to reach from the third, to the ninth step.
Field Experiments
Vertical jumps, sprints, and short distance runs are
sometimes used to test anaerobic power and capacity.
For vertical leaps, several modalities are used. Sometimes
the contestants use their arms, or do not. Often the test will be
performed on a force platform, and power values are calculated. Also, it
may be performed on the field to test work (force*distance). It is
important to note that the height of vertical jump and peak power
determined by force plate information are highly correlated (r=.92). As
such, vertical leap height is an acceptable measurement of anaerobic
alactic power (Vandewalle, et al., 1987).
Sprints are related to all out activities. Runs cover short
time distances, and can therefore be used to test anaerobic metabolism.
Sprints under 15 seconds can cover the alactic system, while sprints from
30-120 seconds can indicate LA power and capacity. Faster speeds would
indicate enhanced power and/or capacity.
Note:
Though these are generally utilized, because of
specificity, anaerobic power is best measured using similar procedures
within the criterion task (i.e. power on a bench press, tests power on the
bench press).
Wingate Anaerobic Test
The Wingate Anaerobic Test is probably the most well-known
and useful modality for testing anaerobic capacity and power. Moreover,
many participants claim that this is the cruelest anaerobic test in
existence. It consists of a 30 second all out ride on a bicycle ergometer,
with resistance according to body weight. It is short, but quite effective
for tearing muscle fibers and testing anaerobic energy systems at various
levels. Resistance for children, adult females, and adult males are .0075,
.086, and .095 kilograms per kilogram of body weight, respectively.
Athletes may need as much as .1 kg.kg-1 of body weight. Additionally, the
revolutions of the flywheel are counted per second amidst the experiment.
Computer-generated results determine 3 distinct variables from the
experiment. These are: mean power, fatigue index, and peak power (Plowman
& Smith, 2001).
“Mean power” refers to the average power
(force*distance/time) exhibited during short (30 seconds) work. “Fatigue
Index” means the percentage of peak power drop off amidst high intensity,
short duration work. And lastly, the term “peak power” is defined as the
maximal power performed during only 5 seconds of work. These variables are
calculated accordingly:
-
Mean Power (kgm per
30 sec) = the total amount of revolutions in 30 seconds*distance that
the flywheel travels per revolution (m)* force settings (kg). This can
also be expressed as MP = revolutions (total) in 30 sec * D.REV-1*F
-
Fatigue Index (%) =
[1 – (lowest power kgm.5 seconds-1 %(peak power kgm.5 seconds-1)] *100
or FI=[1 – (LP/PP) *100.
Note:
Calculating the lowest
power is the same as peak power, except you would use the lowest power
during 5 seconds of a 30 second ride instead of the highest power; this
would typically be the last 5 seconds of the ride rather than the first 5
or so seconds, as you would use with peak power.
-
Peak Power (kgm.5
seconds-1) = maximal revolutions in 5 sec*distance that the flywheel
travels per revolution (m)*force setting (kg) or PP = rev (max) in 5
sec*D.rev-1*F
Mean Power
Using the samples of 58.45 revolutions per minute, a
flywheel distance of 9 meters per revolution, and 7 kg of resistance, here
is an example of this method:
MP= 58.45 rev * 9 m.rev-1 * 7 kg= 3682.35 kgm.30 seconds
Translated to one minute, this would be:
MP= 3682.35 kgm.30 seconds * 2= 7364.7 kgm.minute-1
According to body weight (using the measurement for
athletes; 7kg/.1=70kg) this would be:
7364.7 kgm.minute-1/70kg=105.21 kgm.min-1.kg-1
Using a measurement of watts (one watt=6.12 kgm.min-1):
105.21 kgm.min-1.kg-1/6.12 kgm.min-1= 17.2 W.k.g-1
Since the time energy continuum for glycolysis is dominate
at 30 seconds, this variable is often used to determine LA anaerobic
capacity.
Fatigue Index
With the stats of the 300 kgm of peak power in 5 seconds,
and 150 kgm of lowest power per 5 seconds, here is an example of fatigue
index:
[1- (150 kg.5sec-1/300kg.5 sec-1)] * 100= 50% FI
The Fatigue index is a measure of the peak power drop of
during high intensity, short duration work. This index, in theory, would
determine glycolytic power.
Peak Power
Here is an example of Peak Power in 30 seconds, using the
numbers given in the aforementioned variables, with the additional
statistic of 4.8 maximal revolutions per five seconds:
PP=4.76 rev * 9 m.rev-1 * 7 kg= 300
To convert this relative to body weight, watts, or to a
minute, use the same calculations listed under MP.
Peak power is primarily used to determine alactic capacity.
However, results show that a significant amount of lactic acid can be
produced with 10 seconds of high intensity work (Bar-Or, 1987). Therefore
glycolysis, by necessity, occurs immediately with the alactic acid system.
As such, peak power is not solely a determinate of alactic capacity, but
is nonetheless a useful methodology.
Note:
Though the Wingate test is primarily a measure of anaerobic
power and capacity, the aerobic system does participant (from 13-30%)
during this 30 second ride.
It is still an excellent modality, however, and compares
favorably with other solidified tests of anaerobic power and capacity
(correlations rank above .75) (Patton and Duggan, 1987).
Conclusion
The anaerobic systems are an integral part in supramaximal
exercise modalities. A clear understanding of these systems will afford
the athlete a needed edge for manipulative and training strategies.
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