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Physiology
and Training
SUBTITLE
Why do we train????
▪ The human body is an amazing ‘machine’ that will adapt I’s
systems to maintain homeostasis. As a result of this and our
intelligence we have the ability to survive in a variety of
environments:
▪
▪
▪
▪
Hot
Cold
Humid
Etc
▪ We have also used this knowledge to manipulate our bodies to
perform at higher levels in a number of sporting disciplines. We do
this predominately by training and training smart!
It all begins with energy
Energy is required for all kinds of bodily processes including growth and
development, repair, the transport of various substances between cells and
of course, muscle contraction. It is this last area that Exercise Scientists are
most interested in when they talk about energy systems.
Whether it's during a marathon run or one explosive movement like a tennis
serve, skeletal muscle is powered by one and only one compound...
adenosine triphosphate (ATP).
However, the body stores only a small quantity of this 'energy currency'
within the cells and its enough to power just a few seconds of all-out
exercise . So the body must replace or resynthesize ATP on an ongoing
basis. Understanding how it does this is the key to understanding energy
systems.
An ATP molecule consists of adenosine and three
(tri) inorganic phosphate groups. When a molecule of
ATP is combined with water (a process called
hydrolysis), the last phosphate group splits away and
releases energy. The molecule of
adenosine triphosphate now becomes
adenosine diphosphate or ADP
To replenish the limited stores of ATP, chemical
reactions add a phosphate group back to ADP to create
ATP. This process is called phosphorylation. If this
occurs in the presence of oxygen it is labelled aerobic
metabolism or oxidative phosphorylation. If it occurs
without oxygen it is labelled anaerobic metabolism
The Glycolytic System
Glycolysis literally means the breakdown (lysis) of glucose and consists of a series of enzymatic reactions. Remember
that the carbohydrates we eat supply the body with glucose, which can be stored as glycogen in the muscles or liver
for later use.
The end product of glycolysis is pyruvic acid. Pyruvic acid can then be either funnelled through a process called the
Krebs cycle or converted into lactic acid.
Traditionally, if the final product was lactic acid, the process was labelled anaerobic glycolysis and if the final product
remained as pyruvate the process was labelled aerobic glycolysis.
However, oxygen availability only determines the fate of the end product and is not required for the actual process of
glycolysis itself. In fact, oxygen availability has been shown to have little to do with which of the two end products,
lactate or pyruvate is produced. Hence the terms aerobic meaning with oxygen and anaerobic meaning without
oxygen become a bit misleading .
Alternative terms that are often used are fast glycolysis if the final product is lactic acid and slow glycolysis for the
process that leads to pyruvate being funnelled through the Krebs cycle. As its name would suggest the fast glycolitic
system can produce energy at a greater rate than slow glycolysis. However, because the end product of fast glycolysis
is lactic acid, it can quickly accumulate and is thought to lead to muscular fatigue.
Mitochondria…………
▪ And energy begins within cells which contain mitochondria…
▪ Mitochondria are cellular organelles that function as power plants within
a cell. In the same way that a local power plant produces electricity for
an entire city, mitochondria are responsible for the production of energy
derived from the breakdown of carbohydrates and fatty
acids. Mitochondria oxidize or “burn” carbohydrates, amino acids and
fatty acids for energy, yielding ATP. ATP (Adenosine Triphosphate) is the
cellular form of energy utilized by cellular processes all throughout the
body, providing the energy to pump your heart, power neurons in your
brain, contract muscles in your limbs, exchange gases in your lungs,
extract nutrients from food and regulate body temperature, just to name
a few.
▪ Simply stated, mitochondria produce ATP, and ATP is absolutely essential
for survival. Without a sufficient generation of ATP, life would cease to
exist.
Two Content Layout with Table
▪ Where are Mitochondria Found?
▪ Mitochondria are located in every cell type
and tissue in the human body, from your
brain to your thyroid gland to your Achilles
tendon. In short – trillions of mitochondria
are distributed all throughout your body with
the sole purpose of generating ATP. Red
blood cells are the only cell type that do not
contain mitochondria.
▪ Muscles contain the highest mitochondrial
content of any tissue in your body, in order
to provide massive amounts of ATP for
movement and exercise. Muscle is
generally divided into three types – white
muscle, red muscle and mixed
muscle. The terms “red” and “white” are
derived from the way these muscles
appear during surgery or autopsies, but
largely refer to the mitochondrial content
of the muscle itself.
Mitochondrial Biogenesis
▪ What is Mitochondrial Biogenesis?
▪ Mitochondrial biogenesis is a
process that was first described over
40 years ago by a pioneer in the
field of exercise physiology
named John Hollosczy, a professor
at Washington University in St.
Louis, MO. Think of him as the
godfather of exercise physiology. In
his seminal paper on the effects of
exercise on mitochondrial structure
and function, he found that
endurance training induced large
increases in muscle mitochondrial
content and increased the ability of
muscle to uptake glucose during
and after exercise.
▪ The result of mitochondrial
biogenesis is an expansion of the
network of mitochondria within a
cell, and an increase in the maximal
amount of ATP that can be
generated during intense
exercise. In short – more
mitochondria means more ATP
production at peak exercise
conditions.
Exercise is the Most Effective Way to Make New
Mitochondria
▪ Exercise is the Most Effective Way to Make New
Mitochondria
▪ Muscle Mitochondria: Use Them or Lose Them!
▪ Exercise is the most potent signal for the increased
production of mitochondria in muscle, by increasing the
ability of the muscle to burn carbohydrates and fatty
acids for ATP.
▪ Chronic disuse of muscle, sedentary behaviour and aging
each independently result in a decline in mitochondrial
content and function, leading to the production of free
radicals and cell death. The muscle tissue of people with
type 2 diabetes has also been extensively studied,
revealing gross defects in mitochondrial number and
function.
▪ When you perform exercise, muscle cells generate a lowenergy signal known as AMP, and the accumulation of
AMP over time signals for increased ATP
production. occurs in the resting state immediately
following exercise.
▪ In response to a large demand for ATP production,
muscle cells respond by overcompensating in their ability
to produce energy for the next round of exercise, by
inducing mitochondrial biogenesis in the resting state.
▪ By doing this, mitochondria are able to consume larger
amounts of oxygen, carbohydrates and fatty acids, the
fuels needed to power the production of ATP. The ability
of muscles to overcompensate for exercise “stress” is
exactly why frequent exercise results in increased
strength, endurance, resistance to fatigue and whole
body fitness.
So what exactly is occurring in them
mitochondria?
The Krebs cycle
aka citric acid cycle
aka TCA cycle
▪
The pyruvic acid (3C) enters the matrix of the mitochondrion
where it is oxidized (i.e. 2H removed) and a carbon dioxide is
lost. Thus forming a two carbon molecule called acetyl-CoA
(2C).
▪
The hydrogens which have been removed join with NAD to
form NADH2.
▪
It begins when the 2-carbon acetyl CoA joins with a 4-carbon
compound to form a 6- carbon compound called Citric acid.
▪
Citric acid (6C) is gradually converted back to the 4-carbon
compound ready to start the cycle once more.
▪
The carbons removed are released as CO2.
▪
The hydrogens, which are removed, join with NAD to form
NADH2.
What the????
▪ In essence post the pyruvic acid
going through the complex
chemical reaction in the Krebs
cycle the body can in fact
walkaway with 36 ATP armed
and ready to use!!!! At a mere
cost of 2 ATP BOOOM!!!
▪ Thus, the aerobic system
produces 18 times more ATP
than does anaerobic glycolysis
from each glucose molecule.
▪ Basically this means you can
keep swimming just keep
swimming keep swimming……
Okay so now we got the energy what do our
muscles do with it???
▪ To understand this we need to
understand the structure of the
muscle
▪ The skeletal muscles are usually
made up of a muscle body and two
tendons which attach to the bones.
These muscles contract to create
movement,
▪ The muscle body is made up of
thousands of muscle fibres known
as fasciculi.
▪ Fascuculi are then made up of many
myofibrils which are similar to the
wires in a telephone cable.
Okay so now we got the energy what do our
muscles do with it???
▪ The myofibrils are divided into sections
known as sarcomeres.
▪ Sarcomeres run the length of the
myofibrils and each are separated by
what we refer to as the z line.
▪ Each myofibril sarcomere is further
divided into what are know as
myofilaments;
▪ A thick filament (myosin)
▪ A thin filament (actin)
▪ These in turn are surrounded by a
gelatin like substance sarcoplasm,
which contains mitochondria, myoglobin
(reasponsible for carrying O2 from the
blood to the mitachiondria) CP,
glycogen, fat and ATP.
Okay so now we got the energy what do our
muscles do with it???
▪ Actin and myosi filaments take up
different parts of the length of the
sarcomere.
▪ The light section that only contains
the thin actin filaments are known
as the I-Band.
▪ A-Band refers to where both actin
and myosin filaments overlap and is
a darker section.
▪ The H-Zone is very small and is
located in the middle of the A band,
this is where only the thick myosin
filaments occur.
So how do we control these muscles?
▪ Sensory neurons send messages
from the sense recpetors to the
brain, motor neurons carry
messages from the brain to the
Central Nervous sytem and
ultimately to the muscle.
▪ Many nerve cells extend the
length of a myofibril a bit like
sarcomeres.
▪ Each motor unit controls one
small portion of the muscle
The all or nothing principle
▪ The all or nothing principle means
that muscle fibres either contract
maximally along their length or not
at all. So when stimulated muscle
fibres contract to their maximum
level and when not stimulated there
is no contraction. In this way the
force generated by a muscle is not
regulated by the level of contraction
by individual fibres but rather it is
due to the number of muscle fibres
that are recruited to contract. This is
called muscle fibre recruitment.
▪ Hence contraction strength is
regulated by the message sent from
the brain in terms of how many
fibres are required for the
movement
Sliding Filament Theory
▪
Here is what happens in detail. The process of a muscle contracting can
be divided into 5 sections:
▪
A nervous impulse arrives at the neuromuscular junction
▪
In the presence of high concentrations of Ca+, the Ca+ binds to Troponin,
changing its shape and so moving Tropomyosin from the active site of
the Actin. The Myosin filaments can now attach to the Actin, forming a
cross-bridge.
▪
The breakdown of ATP releases energy which enables the Myosin to pull
the Actin filaments inwards and so shortening the muscle. This occurs
along the entire length of every myofibril in the muscle cell.
▪
The Myosin detaches from the Actin and the cross-bridge is broken when
an ATP molecule binds to the Myosin head. When the ATP is then broken
down the Myosin head can again attach to an Actin binding site further
along the Actin filament and repeat the 'power stroke'. This repeated
pulling of the Actin over the myosin is often known as the ratchet
mechanism.
▪
This process of muscular contraction can last for as long as there is
adequate ATP and Ca+ stores. Once the impulse stops the Ca+ is
pumped back to the Sarcoplasmic Reticulum and the Actin returns to its
resting position causing the muscle to lengthen and relax.
▪ Partially Contracted Muscle
▪ The diagram shows a partially
contracted muscle where there is
more overlapping of the myosin
and actin with lots of potential
for cross bridges to form. The I bands and H - zone are shortened
▪ Fully Contracted Muscle
▪ The diagram shows a fully
contracted muscle with lots of
overlap between the actin and
myosin. Because the thin actin
filaments have overlapped there
is a reduced potential for cross
bridges to form again. Therefore
there will be low force production
from the muscle.
Aerobic Limitations
▪ Why do we not use the Aerobic system all
the time? Basically because it is not fast!
▪ 100 metre sprint an athlete requires
around 8 litres of oxygen in 10 seconds, a
trained male can supply approx 5 litres of
oxygen per minute when working
aerobically.
▪ It takes a couple of minutes for the body
to respond to the demands and
requirements of exercise, i.e. heart rate to
be at ‘steady state’ thus we work
aerobically until all systems catch up, we
call this oxygen deficit, the body generally
stores lactic acid as a result of this in
manageable amounts, when we complete
exercise we take some time before
returning to a resting state, we call this
oxygen debt as the body is repaying the
oxygen used in the oxygen deficit stage.
Oxygen Delivery to the Working Muscles
▪ We now know that for the krebs
cycle to occur oxygen needs to be
present. There are a number of
systems which deliver this oxygen
to the working muscles. The
more efficient the bodies ability
to deliver oxygen to these
muscles the greater the working
capacity, we call this aerobic
capacity.
Lung Capacity
Gas Exchange
▪ Gas will diffuse from areas of high concentrations to low
concentrations.
▪ Blood arriving at the lungs is high in CO2 and low in Oxygen,
therefore C02 will be diffused into the lungs from the blood to be
breathed out
▪ Oxygen will be diffused from the lungs to the blood to be carried
around the body.
The Pump
▪ The heart has two sides, separated by an
inner wall called the septum. The right
side of the heart pumps blood to the
lungs to pick up oxygen. The left side of
the heart receives the oxygen-rich blood
from the lungs and pumps it to the body.
▪ The heart has four chambers and four
valves and is connected to various blood
vessels. Veins are blood vessels that carry
blood from the body to the heart. Arteries
are blood vessels that carry blood away
from the heart to the body.
Stroke Volume
Stroke volume: The amount of blood pumped by the
left ventricle of the heart in one contraction.
The stroke volume is not all the blood contained in
the left ventricle; normally, only about two-thirds of
the blood in the ventricle is expelled with each beat.
Together with the heart rate, the stroke volume
determines the output of blood by the heart per
minute (cardiac output).
Heart Rate
When your heart pumps blood through your
arteries, it creates a pulse that you can feel in the
arteries close to the skin's surface. Pulses can be
most easily felt at the wrist, elbow, groin, feet and
neck.
Heart rates increase in response to the body
needing more oxygen or nutrients e.g., when
exercising, or when you may need it to run for your
life when being chased by a lion (the fight or flight
response)!
The Pump
Cardiac Output
Cardiac output (CO) is the term used to show
the amount of blood pumped per minute by
each ventricle. When your body's at rest, your
heart beats about 75 times per minute. Each
time it pumps, it pushes out about 75 milliliters
of blood, which is about a third of a cup - it's
about the amount that you could hold in your
cupped hand. When you multiply the number of
heartbeats per minute times the amount of
blood being pumped during each heartbeat, we
get the cardiac output.
If we do the math using the examples above, we see
that 75 heartbeats per minute times 75 milliliters of
blood pumped during each heartbeat equals the
average cardiac output of about 5.6 liters of blood
pumped through your heart each minute. That's a lot
of blood, and if you consider that large bottles of
soda often come in 2 litre containers, that means
that your heart pumps the contents of more than 2
and a half of these soda bottles every minute.
Areteriovenous Oxygen Difference
▪ The arteriovenous oxygen difference is the difference between the
oxygen contents of the arterial blood and mixed venous blood. It is
a reflection of the amount of oxygen extracted from the blood by
the muscles. Obviously, the more oxygen that is actually extracted
from the blood, the more oxygen there is for aerobic energy
production. The oxygen content of venous blood can be reduced to
one-half to one-third of an individual’s resting levels by the
exercising muscles.
Maximum Oxygen Uptake
▪ Stoke Volume, Heart Rate, Cardiac
Output and Arteriovenous Oxygen
difference all combine to create
our Maximum Oxygen Uptake or
VO2max it is a beautiful thing!!!!!
▪ VO2 max is the maximum amount
of oxygen in millilitres, one can use
in one minute per kilogram of body
weight. Those who are fit have
higher VO2 max values and can
exercise more intensely than those
who are not as well conditioned.
Average VO2 max (ml/kg/min) for non-trained athletes
Age
Male
Female
10-19
47-56
38-46
20-29
43-52
33-42
30-39
39-48
30-38
40-49
36-44
26-35
50-59
34-41
24-33
60-69
31-38
22-30
70-79
28-35
20-27
Sport
Age
Male
Female
Baseball
18-32
48-56
52-57
Basketball
18-30
40-60
43-60
Cycling
18-26
62-74
47-57
Canoeing
22-28
55-67
48-52
Football (USA)
20-36
42-60
Gymnastics
18-22
52-58
Ice Hockey
10-30
50-63
35-50
Specific Sports
Specific Athletes
Sport
Age
Male
Female
Baseball
18-32
48-56
52-57
Basketball
18-30
40-60
43-60
Cycling
18-26
62-74
47-57
Canoeing
22-28
55-67
48-52
Football (USA)
20-36
42-60
Gymnastics
18-22
52-58
Ice Hockey
10-30
50-63
Orienteering
20-60
47-53
46-60
35-50
Rowing
20-35
60-72
58-65
Skiing alpine
18-30
57-68
50-55
Skiing nordic
20-28
65-94
60-75
Soccer
22-28
54-64
50-60
Speed skating
18-24
56-73
44-55
Swimming
10-25
50-70
40-60
Track & Field - Discus
22-30
42-55
Track & Field - Running
18-39
60-85
50-75
Track & Field - Running
40-75
40-60
35-60
Track & Field - Shot
22-30
40-46
Volleyball
18-22
Weight Lifting
20-30
38-52
Wrestling
20-30
52-65
40-56
Individuals
O2 max (ml/kg/min)
Athlete
Gender
Sport/Event
96.0
Espen Harald Bjerke
Male
Cross Country Skiing
96.0
Bjorn Daehlie
Male
Cross Country Skiing
92.5
Greg LeMond
Male
Cycling
92.0
Matt Carpenter
Male
Marathon Runner
92.0
Tore Ruud Hofstad
Male
Cross Country Skiing
91.0
Harri Kirvesniem
Male
Cross Country Skiing
88.0
Miguel Indurain
Male
Cycling
87.4
Marius Bakken
Male
5K Runner
85.0
Dave Bedford
Male
10K Runner
85.0
John Ngugi
Male
Cross Country Runner
73.5
Greta Waitz
Female
Marathon runner
71.2
Ingrid Kristiansen
Female
Marathon Runner
67.2
Rosa Mota
Female
Marathon Runner
Why do you think that Cross Country skiiers have the highest VO2max?
Means to Test V02max
▪ Measuring VO2 max accurately requires an all-out effort (usually on a
treadmill or bicycle) performed under a strict protocol in a sports
performance lab. These protocols involve specific increases in the speed
and intensity of the exercise and collection and measurement of the
volume and oxygen concentration of inhaled and exhaled air. This
determines how much oxygen the athlete is using. An athlete's oxygen
consumption rises in a linear relationship with exercise intensity -- up to a
point.
▪ Multistage Fitness Test
▪ The objective of the Multi-Stage Fitness Test (MSFT), developed by Leger
& Lambert (1982), is to monitor the development of the athlete's
maximum oxygen uptake.
▪ This test is very good for games players as it is specific to the nature of
the sport but, due to the short sharp turns, it is perhaps not suitable for
rowers, runners or cyclists.
So how come I will be forced to stop?!
▪ So my Cardio Respiratory system is supplying plenty of oxygen to
the lungs, my blood has heaps of haemoglobin to carry this
around, my lung is strong and has a powerful stroke volume plus a
quality cardiac output, my muscles are efficient and have plenty of
mitochondria to promote the Krebs cycle and produce more ATP,
basically my aerobic system is the shiz nit……..why can’t I just keep
swimming?
Causes of Fatigue
▪ Lactic Acid Accumulation
▪ Lactic acid is rapidly broken down into a compound called lactate,
resulting in the release of hydrogen ions. Your body can clear
lactate by metabolizing it for energy, but when lactate production
exceeds the clearance rate, it accumulates in your muscles and
bloodstream. While rising levels of lactate are associated with
tired muscles, lactate does not actually cause fatigue. Rather, it is
the increased acidity in your tissues, due to the buildup of
hydrogen ions, that contributes to the sensation of fatigue.
Depletion of Energy Stores
▪ Glycogen Depletion
▪ If glycogen stores are not being replenished with
carbohydrates from food or drinks, glycogen stores
can run out. Once this occurs, the body will find
alternative ways to create more glucose. This process
is called gluconeogenesis, or the formation of glucose
from new sources. The liver will begin to break down
fat and protein to form glucose, which can then be
used for energy. However, this process takes longer
than glycogenolysis, and is therefore considered a less
efficient way of producing energy.
▪ Hypoglycemia
▪ After glycogen stores have been depleted and before
gluconeogenesis kicks in, an athlete may experience
symptoms of hypoglycemia, which occurs when blood
glucose levels are low. During hypoglycemia, a person
may feel extreme fatigue and a near complete loss of
energy, often referred to as "bonking". When this
occurs, it is not uncommon to see athletes collapse
from the extreme fatigue. Dizziness and hallucinations
may also occur under these conditions.
https://www.youtube.com/watch?v=g_utqeQALVE
Elevated Body Temperature
▪ As the corebody temperature
increases vasodilation occurs
which is when blood is directed
to the veils located near the
skin in an effort to cool it
down.
▪ As a result this blood is
directed away from the
working muscles which will
cause fatigue due to no oxygen
arriving for ATP resynthesis.
▪ Central Nervous System Inhibition
▪ Brsin senses fatigue and as a matter of self preservation it transmiots
less messages to the working muscles to contract. Hence an athlete
slows down.
▪ Transmitter Tiredness
▪ Nerve fibres do not connect directly to the muscles but transmit it
through acetylcholine a substance which is released which crosses the
gap. As the muscles fatigue the amount of this substance released is
reduced.
Muscle Fibre Type
▪ Fast Twitch Fibres contain high
stores of PC which mean they
fatiugue less quickly when
operating Anaerobically
▪ Slow twitch muscle fibres
contain greater amounts of
Glycogen and Triglycerides
meaning that they can convert
ATP longer in the aerobic
system
▪ Generally our fibre type make
up is a result of genetics.
Responses to Exercise
▪ When you begin to exercise your body must immediately adjust to
the change in activity level. Energy production must increase to
meet demand with changes to the predominant energy system
and fuel source occuring throughout the exercise in order to
maintain the required level of performance.
Short term effects of exercise
▪ Acute Responses
▪ When we begin to exercise the
body has to respond to the
change in activity level in order to
maintain a constant internal
environment (homeostasis). Here
are the changes which must take
place within
the muscles, respiratory and circ
ulatory system:
Long term responses to exercise
▪ Chronic Responses
▪ Long-term Effects of Exercise
▪ Regular exercise results in
adaptations to the circulatory,
respiratory and muscular
systems in order to help them
perform better under additional
stress. Here are the changes
which must take place within
the muscles, respiratory
system andcirculatory system:
Biomechanics of Running
▪ Summary of Running Form:
▪ 1. Body Position- upright, slight lean from
ground. Head and face relaxed.
▪ 2. Feet- As soon as knee comes through, put
the foot down underneath you. Land mid or
forefoot underneath knee, close to center of
the body.
▪ 3. Arm stroke- controls rhythm, forward and
backwards from the shoulder without side to
side rotation
▪ 4. Hip extension- extend the hip and then leave
it alone.
▪ 5. Rhythm- Control rhythm and speed through
arm stroke and hip extension.
▪ http://www.scienceofrunning.com/2010/08/h
ow-to-run-running-with-proper.html
Biomechanics of Cycling
▪ Most of us don’t spend enough time setting up our
bikes correctly to get the optimum position for speed.
With a little time and understanding, you may be able
to go faster without any hard training sessions or
extra cost.
▪ The most important factor is saddle position: if the
saddle is too low, you won’t be able to make full use
of the power in your legs, and if the saddle is too high
you’ll feel your hips roll from side to side as your legs
stretch too far at the bottom of each pedal stroke.
▪ The fore and aft position of the saddle is also very
important to ensure effective use of your quadriceps
and prevent any knee injuries.
▪ Another common problem for riders is a stiff neck or
shoulders – check your posture throughout your rides
to make sure your neck and shoulders are relaxed to
prevent unnecessary aches and pains, and keep
yourself in the right position to unleash your speed
potential.
Simple Bike Setup
▪ Saddle height: Sit on the bike
with one of the pedals at 6
o’clock. Position your foot so it’s
parallel to the floor. In this
position, your leg should be
almost straight.
▪ Saddle fore and aft: Sitting on
the bike, position one foot
forwards so the crank is parallel
to the floor at 3 o’clock. Hold a
length of string with a weight on
the end at the front of your knee.
The string should drop down in
line with the pedal axle. Adjust if
necessary.
▪
▪ Handlebar height: This depends
on a number of factors such as
suspension travel and the type of
terrain. The higher the bars are,
the more comfortable you’ll feel
but you’ll lose that sense of being
in a race position
▪ Handlebar reach: Make sure you
can reach the bars with your
arms slightly bent. If the bars are
too close your back will not be in
neutral and will become rounded.
If the bars are too far away, you’ll
have to work your core muscles
to stay in position, which can
lead to lower back pain.