WHAT IS YOUR AEROBIC POTENTIAL?
GENETICS: heredity can account for up to 25-50% of the variance seen
between individuals. (e.g. skeletal muscle composition, structure of
cardio respiratory). There is a genetic upper limit beyond which, further
increases in either intensity or volume have no effect on aerobic power
AGE: in general VO2 max is the highest at age 20 and decreases nearly 30
percent by age 65.
GENDER: differences in body size and body composition (%body fat), blood
volume and hemoglobin content, a woman's VO2 max is in general
about 20 percent lower than a man's VO2 max.
ENVIRONMENT: Altitude - Because there is less air pressure, the pressure
difference between lungs and blood is decreased and less O2 enters the
blood, VO2 max decreases as altitude increases above 1600m (5249ft)
FITNESS LEVELS: maximal oxygen uptake increase to training. The
increase is specific to the training (training type, intensity, timing)
Two theories have been proposed:
1. Utilization Theory: sufficient amount of
oxidative enzymes within the cell's
mitochondria. The body's ability to utilize the
available oxygen that determines VO2 max
2.
Presentation Theory: the ability of the
cardiovascular system to deliver oxygen to
active tissues. VO2 max is improved with:
1.
2.
3.
Increased blood volume,
Increased cardiac output (due to increased stroke volume)
Better perfusion of blood into the muscles
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Glycolysis:
2 ATP (substrate-level
phosphorylation)
Kreb’s Cycle:
2 ATP (substrate-level
phosphorylation)
Electron transport &
oxidative phosphorylation:
2 NADH
(glycolysis) = 6ATP
2
NADH (acetyl CoA) = 6ATP
6 NADH (Kreb’s) = 18 ATP
2 FADH2 (Kreb’s) = 4 ATP
38 TOTAL ATP/glucose
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AEROBIC METABOLISM - take place in the
muscle Sarcoplasm. (Muscle Cell)
VO2 max change - depends on the starting
point. The fitter an individual is to begin with,
the less potential there is for an increase
VO2 max plateau - further improvements in
performance can still occur.
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Two major reasons for this are
improvements:
◦ in anaerobic threshold
◦ economy in sport technique.
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Fermentation:
lactic acid~
pyruvate to lactate
There are two systems within Anaerobic metabolism
1. ATP-PC System
 The breakdown of ATP increases ADP triggering an
enzyme known as Creatine Kinase to initiate the
breakdown of PC providing the energy required to
resynthesise ATP at a fast rate.
 We only have 120g of Creatine within our bodies
and so this repeated breaking down of PC in order
to produce energy to resynthesise ATP is
temporary and can only last a maximum of 10
seconds. Therefore the ATP-PC system is used
mainly for bursts of speed.
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2. Lactic Acid System
 Sometimes also known as Anaerobic Glycolysis due
to the initial process being the same as aerobic
glycolysis only without oxygen.
 Carbohydrate broken down to Pyruvic acid and 2
molecules of ATP.
 To try to prevent an increase in acidity the pyruvic
acid accepts the H+, forming Lactic acid.
 Lactic acid is thought to interefere with muscle
contraction due to disrupting the binding of Calcium
to Troponin. Acidity also stimulates free nerve
endings within the muscle, causing pain. Due to
lactic acid production, this energy system can only
be predominant for up to 2 minutes.
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Not the same thing
Lactic Acid is the endproduct of anaerobic
glycolysis
Blood lactate is a salt produced from the
recombination of lactic acid and ions
Lactate is an importance substrate that can
be used during submaximal exercise,
recovery and rest
Training accelerates lactate clearance
VO2 max is NOT a good predictor of
performance
More significant than VO2 max is the speed at
which an athlete can run, bike etc. at VO2
max.
A high VO2 max may be a prerequisite for
performance in endurance events at the
highest level BUT……
other markers such as lactate threshold are
more predictive of performance
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the speed at lactate threshold is more
significant than the actual value itself.
The point during exercise of increasing
intensity at which blood lactate begins to
accumulate above resting levels, where
lactate clearance is no longer able to keep up
with lactate production.