Transcript Exercise Physiology - Mrs N Benedict

Exercise Physiology
Topic Cue Cards
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ATP
Adenosine triphosphate, more commonly referred to as ATP, is the
only usable form of energy in the body
The energy we derive from the foods we eat such as carbohydrates,
has to be converted into ATP before the potential energy in them can
be used
ATP consists of one molecule of adenosine and three phosphates
Energy is released from ATP by breaking down the bonds (which are a
source of a lot of potential energy) that hold it together
Enzymes are used to break down compounds. ATPase is the enzyme
used to break down ATP into ADP + P
This reaction is exothermic because energy is released
A reaction that needs energy to work is called an endothermic
reaction
Rebuilding or re-synthesising ATP from ADP + P is an endothermic
reaction
Energy released from the breakdown of ATP is converted to kinetic &
heat energy
ATPase
ATP  ADP + P + energy
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Key point Make
sure you know
how the energy is
released from
ATP
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ATP-PC System
Phosphocreatine (PC) is an energy-rich phosphate compound found
in the sarcoplasm of the muscles, and is readily available. Its rapid
availability is important for providing contractions of high power,
such as in a 100 m sprint or in a short burst of intense activity
during a game, for example a smash in tennis or a slam-dunk In
basketball. However, there is only enough PC to last for up to 10
seconds and it can only be replenished when the intensity of the
activity is sub-maximal
The ATP-PC system re-synthesises ATP when the enzyme creatine
kinase detects high levels of ADP. It breaks down the
phosphocreatine (as potential energy is stored in the bonds of this
compound) to phosphate and creatine, releasing energy. This
energy is then used to convert ADP to ATP in a coupled reaction
(where more than one reaction takes place)
For every molecule of PC broken down, enough energy is released
to create one molecule of ATP. This means that the system is not
very efficient but it does have the advantage of not producing
fatiguing by-products and its use is important in delaying the onset
of the lactic acid system
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Key point The
advantages of
this system are
that it is quick
and easy to use
and there are no
by-products. The
disadvantage is
that the energy
yield is only one
molecule of ATP
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The Lactic Acid System
Once PC is depleted, the lactic acid system takes over and resynthesises ATP. This system, like the ATP-PC system, is an anaerobic
process where the energy comes from the food we eat namely
carbohydrate, which is digested to glucose
Glucose is stored in the muscles and liver as glycogen. Before glycogen
can be used to provide energy to make ATP, it has to be converted to
glucose, This process is called glycolysis
The lactic acid system is sometimes referred to as anaerobic glycolysis
due to the absence of oxygen, In a series of reactions, the glucose
molecule is broken down into two molecules of pyruvic acid, which are
then converted to lactic acid because oxygen is not available
The main enzyme responsible for the anaerobic breakdown of glucose
is PFK (phosphofructokinase), activated by low levels of
phosphocreatine, The energy released from the breakdown of each
molecule of glucose is used to make two molecules of ATP
The lactic acid system provides energy for high-intensity activities
lasting up to 3 minutes but peaking at 1 minute, for example the 400m
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The main
disadvantage of
using this energy
system is the
formation of lactic
acid. If lactic acid
accumulates in the
muscle, the pH of
the body is lowered
and this has an
effect on enzyme
action. PFK, the
controlling enzyme,
is then inhibited and
the ability to re-generate ATP is reduced. This affects performance, for
example ‘burning out’ at the end of a race
Key point When stating the use of this system, always refer to
the intensity and duration of the activity in your examples
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The Aerobic System: Glycolysis
The aerobic system needs oxygen. Glucose can be fully broken down
in the presence of oxygen. However, at the start of exercise more
oxygen is needed to break down glucose at a rate that matches the
demand for ATP. Until more oxygen can reach the working muscle,
through an increase in heart rate and ventilation rate, we have to
use the ATP-PC and lactic acid systems. This means the aerobic
system usually becomes predominant within 1-2 minutes
The aerobic system is a complex chain of events consisting of three
stages. The first stage is glycolysis. This is similar to anaerobic
glycolysis. ATP is re-synthesised from the breakdown of glucose. In
a series of reactions, the glucose molecule is broken down into two
molecules of pyruvic acid. But since, in this case, oxygen is present
the reaction can proceed further than in anaerobic glycolysis and
lactic acid is not produced
This reaction occurs in the sarcoplasm of the muscle and the energy
released from the breakdown of each molecule of glucose is used to
make two molecules of ATP
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Key point The
aerobic system
uses oxygen. The
complete
breakdown of
glucose yields 38
molecules of ATP,
as opposed to two
in the lactic acid
system and one in
the ATP-PC system.
Therefore the
aerobic system is a
much more efficient
method of resynthesising ATP
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The Aerobic System: Krebs Cycle
Pyruvic acid is broken down and diffuses into the matrix of the
mitochondria, combining with coenzyme A (CoA) to form acetyl
coenzyme A
A coenzyme is a molecule that can transport atoms from one reaction
to another
A complex cycle of reactions then occurs in a process known as the
Krebs cycle:
 The acetyl CoA combines with oxaloacetic acid, forming citric acid,
which is then oxidised
 The reactions that occur result in the production of two molecules
of ATP
 Oxaloacetic acid is regenerated and the whole series of reactions
begins again
 Carbon dioxide is formed as a waste product and this is simply
breathed out
 Hydrogen is removed during the oxidation process and taken to the
electron transport chain
This cycle is also referred to as the citric acid cycle or the tricarboxylic acid (TCA) cycle
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Key point The
three main
features t o
remember about
the Krebs cycle
are:
• carbon dioxide is
produced as a
waste product
• hydrogen is
removed
• The energy yield
is two molecules
of ATP
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The Aerobic System: Electron Transport Chain
The function of the electron transport chain is to enable the controlled
release of free energy to drive the re-synthesis of ATP. The electron
transport chain is the final stage of the aerobic pathway. It is a
complex system which is simplified as follows
 The hydrogen atoms removed during the Krebs cycle are
transferred to the electron transport chain by hydrogen carriers
(NAD and FAD)
 This occurs in the cristae of the inner membranes of the
mitochondria
 Within this inner membrane are the electron carriers of the
respiratory chain
 Here, the hydrogen splits into hydrogen ions and electrons, which
are charged with potential energy
 The hydrogen ions are oxidised to form water: while the electrons
provide the energy to re-synthesise ATP
 Water as a by-product is secreted as sweat
In the course of this process, 34 molecules of ATP are formed
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If we add the energy yield from the electron transport chain
(34 molecules of ATP) to that from the Krebs cycle (2
molecules) and glycolysis (2 molecules), we can see that the
total breakdown of one molecule of glycogen can provide
enough energy to resynthesise 38 molecules of ATP
Key point The three main
things to remember about the
electron transport chain are:
 Water is formed
 It occurs in the cristae of
the mitochondria
 The energy yield is 34
molecules of ATP
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The Aerobic System: an Overview
The aerobic system breaks down glucose into carbon dioxide and
water. The presence of oxygen makes it much more efficient than
anaerobic glycolysis, The complete oxidation of glucose can produce
up to 38 molecules of ATP in three stages:
 Glycolysis
 the Krebs cycle
 the electron transport chain
The aerobic system is the most efficient for producing energy but the
reactions that occur throughout this system rely on oxygen
At the start of exercise, or for high-intensity exercise such as sprinting,
oxygen is not always available in sufficient quantities for these
reactions to occur: so other methods of replenishing ATP have to be
used
Since the aerobic system produces huge quantities of ATP, it is
predominant in endurance-based activities where energy is required
over a long period of time. Examples of such low-intensity exercise
activities include jogging and power walking
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Energy system:
Type of reaction:
Chemical or food used:
Site of reaction:
Controlling enzyme:
Aerobic
Aerobic, coupled
Glucose
Fats
 Krebs cycle – matrix of the mitochondria
 Electron transport chain – cristae of the
mitochondria
PFK
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Energy yield:
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By-products
Duration:
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Glycolysis = two molecules of ATP
Krebs cycle = two molecules of ATP
Electron transport chain = 34 molecules of
ATP
Krebs cycle – carbon dioxide
Electron transport chain – water
Continuous
Key point The table above summarises what you need to
know about the aerobic system for the exam
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The Energy Continuum
When we start to exercise, the demand for energy rises rapidly. Although
all three energy systems are always working at the same time, one of them
will be predominant
The intensity and duration of the activity are the factors that decide which
energy system dominates. For example, jogging is a long-duration, submaximal exercise, so the aerobic system will be the predominant energy
system. A highly explosive, short duration activity, such as the 100 m, uses
the ATP-PC system, However: during a game (e.g., football) there will be a
mix of all three energy systems in use, with the performer moving from
one to another: This continual shifting between the energy system
thresholds is known as the energy continuum
The use of the energy continuum can be illustrated by looking at the
1500m. The energy sources for the 1500 m are very specific:
 During the first 10 seconds, the ATP-PC system is the main method of
re-synthesising ATP
 The lactic acid system is then used during the next minute
 In the middle of the race the pace settles into a short aerobic phase
 This is followed by a return to the lactic acid system for the final
sprint for the line
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The ATP-PC-lactic acid threshold is the point at which the
ATP-PC energy system is exhausted and the lactic acid
system takes over
The lactic acid-aerobic threshold is the point at which th3e
lactic acid system is exhausted and the aerobic system takes
over
The energy continuum
Key point Make sure that when you give examples of team
games you always state the intensity and duration
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Food fuels and energy systems
Food is the basic form of energy for ATP resynthesis. The main energy
foods are:
 carbohydrates - stored as glycogen and converted into glucose during
exercise
 fats - stored as triglycerides and converted to free fatty acids when
required
 protein - approximately 10% of energy used during exercise comes
from proteins in the form of amino acids
Carbohydrates and fats are the main energy providers; the intensity and
duration of exercise play a key role in determining which of these are
used. The breakdown of fats to free fatty acids requires more oxygen than
is required to break down glycogen, so during high-intensity exercise,
when oxygen is in limited supply, glycogen is the preferred source of
energy
Stores of glycogen are much smaller than stores of fat It is important
during prolonged periods of exercise not to deplete glycogen stores, as
some needs to be conserved for later when the intensity could increase,
for example over the last kilometre of a marathon
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Key point Lactic
acid can also be
used as an energy
source. During
low-intensity
exercise, lactic
acid can be
oxidised to carbon
dioxide and water
and the energy
released used to
resynthesise ATP
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Carbo-loading
A performer in hard training and competition needs to understand
the importance of carbohydrate in the diet Training diets should be
high in carbohydrates and low in fats and proteins
If too little carbohydrate is eaten, the glycogen stores in the
muscles and liver will drop. Obvious signs of glycogen depletion are
tired, heavy muscles, poor performance and, at times, complete
fatigue
Carbo-loading aims to prevent the onset of fatigue during
endurance events. It is a form of dietary manipulation involving
glycogen loading
Before an important competition, a performer eats a diet high in
protein and fats for 3 days and exercises at a relatively high
intensity to burn off any existing carbohydrate stores. This is
followed by 3 days of a diet high in carbohydrates and some light
training. This greatly increases the stores of glycogen in the muscle
If completed properly, carbo-loading can almost double the average
amount of stored carbohydrate found in a trained individual.
However; a disadvantage is that bloating can occur; together with
water retention
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Key point The term
carbo-loading can be
misleading. You need to
be specific and state
the type of
carbohydrate that you
are loading e.g.
glycogen
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Excess post-exercise energy consumption (EPOC)
The recovery process involves returning the body to its preexercise
state. The reactions that take place and how long the process takes
depend on the duration and intensity of the exercise undertaken and the
individual’s level of fitness
After strenuous exercise there are four main tasks that need to be
completed before the exhausted muscle can operate at full efficiency
again:
 replacement of ATP and phosphocreatine
 removal of lactic acid
 replenishment of myoglobin with oxygen
 replacement of glycogen
The first three tasks require a large amount of oxygen. Therefore,
during recovery the body takes in elevated amounts of oxygen and
transports it to the working muscles to maintain a high rate of aerobic
respiration. This surplus energy is then used to help return the body to
its pre-exercise state. This is known as EPOC (excess postexercise
oxygen consumption). The term oxygen debt is no longer used to explain
the whole of the recovery process. It is commonly thought that other
processes occur in addition to those covered by oxygen debt. The term
EPOC incorporates oxygen debt together with those processes requiring
an elevated rate of respiration
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Key point Glycogen
replenishment occurs
when you eat a
carbohydrate meal
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Oxygen deficit and oxygen debt
Oxygen deficit
When we start to exercise, insufficient oxygen is distributed to the
tissues for all the energy production to be met aerobically, so the two
anaerobic systems have to be used. The amount of oxygen that the
subject was short of during the exercise is known as the oxygen deficit
Oxygen debt
The oxygen debt is the amount of oxygen consumed during recovery
above that which would have been consumed at rest during the same
time. An oxygen debt occurs when the body has been working at high
intensity (anaerobically). This usually arises during the first 3 minutes
of exercise or when the anaerobic threshold is exceeded
Oxygen debt has two components:
 the alactacid component (fast replenishment) restoration of
muscle phosphagens (ATP and phosphocreatine)
 the lactacid component (slow replenishment) removal of lactic
acid
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Key point The
graph alongside
often
accompanies
questions on
oxygen debt.
Make sure you are
familiar with it
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Alactic component of oxygen debt
This is often referred to as fast replenishment and involves the restoration of
ATP and phosphocreatine stores. Elevated rates of breathing continue to
supply oxygen to provide the energy for ATP production and phosphocreatine
replenishment. Complete restoration of phosphocreatine takes up to 3 minutes
but 50% of stores can be replenished after only 30 seconds, during which time
up to 4 litres of oxygen are consumed
This knowledge is useful for a coach or performer who will want to prevent
the use of the lactic acid system with its fatiguing by-product. A time-out in
basketball, for example, allows for significant restoration of PC stores
The table below shows the replenishment of muscle phosphagens after
exercise
Percentage of phosphagens replenished
50
75
87
93
97
99
Recovery time
30
60
90
120
150
180
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The graph below shows the relationship between recovery time and
the replenishment of muscle phosphagens after exercise
Key point The three main
points to remember
about the alactic
component are:
 It involves the
restoration of muscle
phosphagens
 Full restoration takes 3
minutes; half takes 30
seconds
 It uses up to 4 litres of
oxygen
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Lactacid component of oxygen debt
The lactacid component of oxygen debt is concerned with the removal of
lactic acid. It refers to the volume of oxygen required to remove lactic acid
from the muscles. This process is slower than the alactacid component and
full recovery may take up to an hour, depending on the intensity and
duration of the exercise
Lactic acid can be removed in four ways:
 oxidation into carbon dioxide and water
 conversion into glycogen
 conversion into protein
 conversion into glucose
The lactacid oxygen recovery begins as soon as lactic acid appears in the
muscle cell, and continues using breathed oxygen until recovery Is
complete. This can take up to 5-6 litres of oxygen In the first half hour of
recovery, removing up to 50% of the lactic acid
Performing a cool down accelerates the process of removing lactic acid as
it ensures a quick and continuous supply of oxygen to the working muscles
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Destination
Oxidised into carbon dioxide and water
Conversion into glycogen, then stored in
muscles/liver
Conversion into protein
Conversion into glucose
Approximate % of lactic acid involved
65
20
10
5
It is important to note that the removal of lactic acid also relies on the buffering capacity
of the body. This weakens the inhibiting effect of lactic acid
In the blood, hydrogen carbonate ions produced by the kidneys absorb the lactate,
which forms carbonic acid. This is then broken down to carbon dioxide and water, both
of which are easily eliminated
Key point The three main points to remember about the
lactacid component are:
 How lactic acid is removed (quicker recovery if active)
 It takes up to an hour or until the next meal
 It uses up to 6 litres of oxygen
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Myglobin and oxygen store replenishment
Myoglobin is found in the sarcoplasm of the cell. It has a high
affinity for oxygen, stores oxygen in the muscle and transports it
from the capillaries to the mitochondria for energy provision
The role of EPOC
After exercise, oxygen stores in the mitochondria are limited or
totally depleted. The surplus of oxygen supplied through EPOC
(excess post-exercise oxygen consumption) helps replenish these
stores, taking up to 2 minutes and using approximately 0.5 litres of
oxygen
It is important to perform an active recovery to maintain elevated
rates of ventilation and heart rate. This speeds up the
replenishment of myoglobin
Aerobic training can increase the amount of myoglobin, especially in
slow-twitch muscle fibres. This results in a greater oxygen supply to
the working muscles so that the performer can work harder for
longer
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Key point It is
important to have
myoglobin stores
replenished because
if oxygen is present,
energy can be
produced aerobically.
This means that the
body does not have
to rely on the
anaerobic energy
systems, saving ATP-PC for short energy bursts and
preventing the use of the lactic acid system with its
fatiguing by-product, lactic acid
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Onset of blood lactate accumulation
Lactate is a product of lactic acid. Lactic acid splits to give lactate
molecules and hydrogen ions. Onset of blood lactate accumulation
(OBLA) is the point at which lactate starts to accumulate In the blood.
This occurs at around 4 mmol lactate per litre of blood
OBLA can be used to predict the endurance capacity of a performer;
since the longer an athlete can delay the build up of blood lactate, the
longer he/she can perform exercise
Lactate accumulation eventually reaches a point at which the
concentration of lactate in the blood is high enough to cause complete
muscle fatigue, with the result that the performer can no longer
continue
The multi-stage fitness test is a good practical example to illustrate
this. The performer eventually reaches a point due to the increasing
intensity of the test, at which energy cannot be provided aerobically.
This means that the performer has to use anaerobic systems to resynthesise ATP. Blood lactate levels start to increase until eventually
muscle fatigue occurs and the performer slows down or is no longer
able to keep up with the bleep
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Key point Lactic acid
is produced during
anaerobic glycolysis
but it will dissociate to
form the salt lactate
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Principles of training
Overload is achieved by increasing one or more of the following (FIT):
 frequency — the number of training sessions per week
 intensity — how hard the performer works
 time — the duration of the session
Progression involves the gradual application of overload. It is
important to overload the body in order to improve fitness, but this
should be done progressively
Specificity involves keeping the training relevant. For example, a
sprinter will do strength training on the muscles required for his event
and speed training to improve the efficiency of the energy system he
uses when competing
Reversibility is often referred to as detraining. If training stops, the
adaptations that have occurred as a result of training deteriorate
Moderation - don't overdo it! Over-training can lead to injury
Variance — a training programme needs to have variety in order to
maintain interest and motivation
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Training can improve and enhance fitness levels. The type of
improvements will depend on the training method used.
However, the principles must be applied to a training regime
in order for any improvement to be made
Key point Make sure
that you can define all
these principles and
apply them to a
practical activity
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Warm-up
A warm-up has both physiological and psychological benefits. It helps
prepare the body for exercise and should always be carried out before
the start of a training session
The first stage of any warm-up is to perform some kind of
cardiovascular exercise such as jogging, gently increasing the pulse.
This increases cardiac output and breathing rate and, through the
vascular shunt, directs more blood to the working muscles
The second stage is the performance of stretching/flexibility exercises,
especially with those joints and muscles that will be most active during
the training session. Each stretch should be held for at least 10
seconds and the stretching session should last for approximately 10
minutes
The third stage should involve the movement patterns that are to be
carried out, for example practising shooting in basketball and netball,
or dribbling in hockey and football
Together these three stages increase the amount of oxygen being
delivered to the muscles and at the same time reduce the risk of injury
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Key point Not all activities
follow this exact warm-up
procedure. For example, a
swimmer will complete stages 1
and 2 but not stage 3
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Cool-down
It is important to perform a cool-down at the end of any physical
activity as it helps to return the body to its pre-exercise state more
quickly
A cool-down consists of some form of light exercise to keep the
heart rate elevated. This keeps blood flow high and allows oxygen
to be flushed through the muscles, oxidising and removing any lactic
acid that remains
Performing light exercise also allows the skeletal muscle pump to
keep working and prevents blood from pooling in the veins. If we
stop exercising suddenly, the amount of blood going back to the
heart drops dramatically. This is because there is little or no muscle
action to maintain the skeletal muscle pump. Consequently, stroke
volume drops and there is a reduction in blood pressure. The
performer will begin to feel dizzy and light-headed
The cool-down is usually followed by a stretching session, working
on the joints and muscles that have been used during the activity
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Key point A cool-
down is performed
to keep the heart
rate elevated so
that we can use the
extra oxygen to
recover more
quickly
39
DOMS
One aim of training is to improve fitness levels. An individual who
wishes to improve strength will often work at higher intensities to
overload the muscle in order to stimulate muscle hypertrophy. When
this occurs, the individual may experience tender and painful muscles
some 24-48 hours after exercise. This is called DOMS, or delayed onset
of muscle soreness
This muscle soreness results from structural damage to muscle fibres
and connective tissue surrounding the fibres. DOMS usually occurs
following excessive eccentric contraction when muscle fibres are put
under a lot of strain. This type of muscular contraction occurs mostly
from weight training and plyometrics
Avoiding DOMS
A thorough warm-up and cool-down can help to avoid the delayed
soreness or at least keep it to a minimum
If eccentric muscle contractions are the major causal factor in DOMS,
training should try to minimise the use of these or at least ensure
training intensity Is increased gradually
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Key point It was
previously thought
that DOMS occurred
from the build-up of
lactic acid. However, it
is now recognised as
structural damage to
soft tissue
41
Continuous training
Continuous training involves exercise without rest intervals and
concentrates on developing endurance. This places stress on the aerobic
energy system. Examples include exercises such as cycling, jogging and
swimming
In order to gain any improvement in aerobic fitness, it is important to
adhere to the following guidelines:
 Frequency — training must be carried out a minimum of two or three
times per week
 Intensity — this should be at about 60-75% of maximum heart rate
 Time — the duration of the training session should be at least 20
minutes but ideally between 30 minutes and 2 hours to ensure the
aerobic system is working fully
 After a few weeks, the body will adapt to the exercise, so resting
heart rate is reduced. Therefore, to ensure the performer is working at
60-75% of maximum heart rate, he/she will have to work harder by
increasing either frequency, intensity or time
 Keep the session specific to the requirements of the activity. It has
been suggested that training should be over a distance of between two
and five times that covered in the activity
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Key point
Continuous
training develops
aerobic
capacity/VO2max
43
Fartlek training
The word 'fartlek' is Swedish and means speed-play This is a slightly
different method of continuous training
A typical fartlek session involves varying the pace of a run by integrating
intense sprints into the workout, and following these with recovery runs in
the form of slow
The route can also be varied to include both uphill and downhill work.
Changing the pace and route in these ways will stress both the aerobic and
anaerobic energy
systems,
Fartlek is a much more demanding type of training and improves an
individual's VO; {max) and recovery process. A typical session lasts for
about 40 minutes, with the intensity ranging from low to high.
The intensity and duration of training are determined by the individual.
Fartlek training offers more variety through the use of both aerobic and
anaerobic work and is greatly beneficial to the games player where the
demands of the game are constantly changing, so that both types of
respiration are required.
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Below are examples of two very different fartlek training sessions
Session A
 10 minutes jogging
 6 x (20 seconds fast running with 80 seconds recovery
 5 minutes walking
 5 minutes jogging
 2 x (run uphill for 1 minute, jog down
 3 minutes jogging
 2 minutes walking
Session B
 Easy jog for 100m
 Sprint for 30m
 Easy jog for 100m
 Sprint for 30m
 Repeat the above four stages three times
 Walk for 1 minute
 Jog at approximately 75% maximum heart rate for 5 minutes
Key point Although fartlek trainign is bcontinuous, it
does include both aerobic and anaerobic respiration
through variety of pace
45
Interval training
Interval training is popular especially among elite athletes. It is used most
frequently in athletics, cycling and swimming and can improve both aerobic and
anaerobic capacities. In interval training, periods of work are interspersed with
recovery periods. Four main variables are used to ensure the training is specific:
 duration of the work interval (or distance)
 intensity or speed of the work interval
 duration of the recovery period
 number of work intervals and recovery periods
It is possible to adapt interval training to overload each of the three energy
systems. Anaerobic intervals would be short distance and high intensity: aerobic
intervals would be long distance and sub-maximal intensity
 ATP-PC intervals have to be short and very high intensity, for example at
90-100% of maximum effort This allows for increases in muscle stores of
ATP and phosphocreatine
 Lactic acid intervals need to be moderate to high intensity, lasting between
15 and 90 seconds. This is so that the athlete can train with some lactic
acid present in order to improve the buffering capacity of the blood
 Aerobic intervals are much longer — up to 10 minutes duration — and at
lower intensity
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Energy system
Duration/distance of work interval
Intensity of work interval
Duration of recovery
Number of work intervals/recovery periods
ATP-PC
10s/60m
High
30s
10
Lactic acid
35s/200m
High
110s
8
Aerobic
6min/1500m
Sub-maximal
5 min
3
Aims of interval training
 ATP_PC system – to improve ATP and PC stores
 Lactic acid system – to increase the buffering capacity of the blood
 Aerobic system – to improve the oxidative capacity of the body
 Key
point The advantage of interval training is
that it can be adapted to suit most requirements,
ranging from the sprinter to the endurance athlete
to the games player
47
Strength training
Some individuals do a form of strength training to improve performance in
their chosen activity
Improvements in strength result from working against some form of
resistance. In this instance, it is also important to make any strengthtraining programme specific to the needs of the activity. To do this, the
following factors must be considered:
 the type of strength to be developed — maximum, elastic or strength
endurance
 the muscle groups to be improved
 the type of muscle contraction performed in the activity — concentric,
eccentric or isometric
Other individuals do strength training for muscle growth. They need to
ensure that any exercises they perform will overload the anaerobic energy
systems, which will result in hypertrophy of fast-twitch fibres
Strength can be improved by carrying out the following types of training:
 weights — high weights for maximum and dynamic strength; low
weights for strength endurance
 circuits for strength endurance
 pulleys and plyometrics for dynamic strength
48
Strength training is important to avoid muscle loss that
occurs through ageing. It can help to increase physical
capacity, improve athletic performance and reduce injury
risk
Key point In
some textbooks,
elastic strength is
also referred to as
power or dynamic
strength
49
Weights
Weight training is usually described in terms of sets and repetitions.
The number of sets and repetitions and the amount of weight lifted
depend on the type of strength to be improved
Before a programme can be designed, it is important to determine the
maximum amount of weight that the performer can lift with one
repetition. Then, if maximum strength is the goal, it will be necessary
to lift high weights with low repetitions, e.g. three sets of 2-6
repetitions at 80-100% of maximum strength. However, if strength
endurance is the goal, it will be necessary to perform more repetitions
of lighter weights, e.g. three sets of 10 repetitions at approximately
50% of maximum strength
In addition, the choice of exercise should relate to the muscle groups
used in sport — both the agonists and antagonists. The exercises are
usually classed in four groups:
 shoulders and arms, e.g. bench press, curls, pull downs
 trunk and back e.g. sit-ups. back hyperextensions
 legs. e.g. squats, calf raises, leg press
 all-body exercises, e.g. power clean, snatch, dead lift
50
Key point Weight
training is excellent
for improving
strength but it does
not replicate
movement patterns
that are performed
during an activity
51
Circuit training
In circuit training, the athlete performs a series of exercises in
succession. These exercises should include;
 arm exercises, e.g. triceps dips and press-ups
 leg exercises, e.g. squats
 trunk exercises, e.g. srt-ups and dorsal raises
 cardiovascular exercises, e.g. jogging and skipping
The resistance used is the athlete's body weight and each exercise
concentrates on a different muscle group to allow for recovery
Structuring circuit training
A circuit is usually designed for general body conditioning and it is
easily adapted to meet the needs of an activity
Most circuits involve the performer working for a period of between 30
seconds and 1 minute, with a similar recovery period. This recovery
period is usually active, involving jogging or walking
Most circuits are completed in pairs, with one person recovering while
the other works
52
Key point Circuit
training can be
adapted to include
skill training while
at the same time
developing
strength. A series
of skills related to
a particular game
is performed,
interspersed with
jogging
53
Pulleys
These are rope or small
bungee-type harnesses
which allow an athlete to
tram against a resistance.
Swimmers are often
attached to an elastic-type
harness. They then swim
until the elastic is tense and
try to maintain this position.
If they stop or slow down,
the elastic rope drags them
in a backwards direction.
The advantage of this
method of strength training
is that the exact movement
pattern is performed while the resistance is applied
The resistance band shown here is a type of pulley. During skills practice, resistance can be applied by wearing
ankle weights or wrist weights
54
Pulleys are useful for building strength. Depending on the types of pulley used, it is possible to
improve motor skill coordination , increase motor unit activation and allow for neurological
adaptation
Key point Pulleys
are nor generally
used for maximum
strength.
Depending on how
they are used,
they can improve
elastic strength
and muscular
endurance
55
Plyometrics
If leg strength is crucial to successful performance, for example in the
long jump and the 100m sprint in athletics, or rebounding in
basketball, then plyometrics is one method of strength training that
improves power or elastic strength
Plyometrics works on the concept that muscles can generate more
force if they have previously been stretched. This occurs in plyometrics
when, on landing, the muscle performs an eccentric contraction
(lengthens under tension) followed immediately by a concentric
contraction as the performer jumps up. This stimulates adaptations
within the neuromuscular system and results in a more powerful
concentric contraction of the muscle group being worked
To develop leg strength, a line of benches, boxes and hurdles is made
and the performer has to jump, hop and leap from one to the other.
Recovery occurs during the walk back to the start line and the exercise
is repeated
Arm strength can be developed by performing press-ups with mid-air
claps or by throwing and catching a medicine ball
56
Strength gains through plyometrics usually become apparent
following a training period of about 8-19 weeks. This is due to
muscle hypertrophy (an increase in the size of the muscle)
Key point
Plyometrics
should only be
performed by
individuals with
a reasonable
amount of leg
strength. The
constant use of
eccentric muscle
contractions can
easily lead to
DOMS
57
Flexibility training
Sometimes called mobility training, flexibility training involves
stretching muscles and connective tissue. A stretch should be held for
at least 10 seconds and a session should last for 10 minutes. With
regular and repeated stretching, this soft tissue can elongate and this
may be beneficial in avoiding injury. There are three main types of
flexibility training:
 Static stretching can be active or passive:
− Active — the performer works on one joint, pushing it beyond
its point of resistance, lengthening the muscles and connective
tissue surrounding it
− Passive — a stretch occurs with the help of an external force,
such as a partner, gravity or a wall
 Ballistic stretching involves performing a stretch with swinging or
bouncing movements to push a body part even further: it is
important that this type of stretching should only be performed by
an individual who is extremely flexible, such as a gymnast or a
dancer
 PNF stands for proprioceptive neuromuscular facilitation. This is
where the muscle is isometrically contracted for a period of at
least 10 seconds. It then relaxes and is contracted again, usually
going further the second time
58
Key point For improvements to
be made, flexibility training
needs to take place three times
per week and best results occur
when the body is warm.
Wearing warm clothes helps to
maintain body temperature
during flexibility training
59
Planning a training programme
to structure a programme so that the individual can achieve optimum
performance. usually in readiness for the competitive season. Periodisation
involves dividing the year into periods when specific training occurs. Some
athletes prefer to use the seasonal approach where the periodised year is
divided into three parts:
 off-season — the period where general conditioning work is carried out
 pre-season — training is more specific to the activity and builds in
intensity
 competitive season — levels of fitness are maintained but the performer
focuses on competition-specific aspects
This seasonal approach can be adapted to macro-, meso-and microcycles,
which describe periods of time that are more prescriptive for individual
needs:
 An athlete will identify a macrocycle (the 'big period') of 6-12 months to
achieve a long-term goal
 The mesocycle relates to a short-term goal within the macrocycle,
which may last for 6-8 weeks
 The microcycle is normally a 1-week training schedule which is
repeated throughout the length of the mesocycle
60
When planning a training programme, it is important to take note of:
 The aim of the training programme, for example a faster time, a
longer distance or simply to score more goals
 Macro-, meso- and microcycles
 Which energy systems need training, for example a a sprinter would do
anaerobic training
 Which fitness components need improving; tests these first and re-test
at the end to see if there is any improvement
 The main muscle groups used
 The type of contractions needed
 The most suitable method of training – for example, if stamina is
important, then some form of continuous training should be
undertaken
 Ways of applying the principles – progression, overload, specificity,
variance, moderation and, to some extent, reversibility
Key point Applying the principles of training to a
programme is crucial if improvement is to be made. As
exercise gets easier, progression should be made to
overload the session
61
Fitness components
Physical fitness is the ability to carry out daily tasks without becoming
overly tired or fatigued. Components of fitness are usually considered
to be either health related or skill related
 Physical/health components are physiologically based and deal
with the physical demands of the activity. They include aerobic
capacity, strength, flexibility and body composition
 Skill/motor components are based on the neuromuscular system
and determine how successfully a skill can be performed. They
include coordination, agility, speed, balance and reaction time
All of these fitness components can be measured, but it is important to
remember that there are differences according to gender:
 The average female has a higher percentage of body fat than the
average male, which arguably can have an effect on VO2(max) and
therefore stamina
 More weight leads to an increase in effort and consequently a
decrease in VO2(max) when this is measured per kilogram of body
mass
 Higher levels of the male sex hormone testosterone can lead to
greater strength gains
62
Key point Make sure
you can define each
fitness component,
describe a method of
evaluation and know
how each can be
improved
63
Aerobic capacity
This is often referred to using terms such as stamina. VO2(max) and
cardiovascular endurance. Whichever term is used, aerobic capacity can
be defined as the ability to take in and use oxygen. This is dependent on
three factors:
 how effectively an individual can inspire and expire
 once they have inspired, how effective the transportation of oxygen
is from the lungs to where it is needed
 how well the oxygen is then used
Aerobic capacity is important for participation in continuous submaximal activity, such as jogging and cycling
In an average performer, it is usual to work at around 65% of VO2(max).
Working harder than this results in crossing the anaerobic threshold,
when the aerobic system is no longer the main energy provider and
instead the ATP-PC and lactic acid systems are the predominant
methods of resynthesising ATP. Elite athletes can work at a much higher
percentage of their VO2(max) before crossing the anaerobic threshold
(usually 85%)
VO2(max) is largely determined genetically and there are also
differences due to gender and age
64
Key point A
definition of
VO2(max) is the
maximum volume of
oxygen consumed
per unit of time. It is
often expressed as
millilitres per minute
per kilogram of body
weight
65
Factors affecting aerobic capacity
Differences in gender
A male long-distance runner has a VO2(max) of approximately
70ml/min/kg. A female long-distance runner has a VO2(max) of around
60ml/min/kg. This is because the average female is smaller than the
average male. Females have:
 a smaller left ventricle and therefore a lower stroke volume
 a lower maximum cardiac output
 a lower blood volume, which results in lower haemoglobin levels
 lower tidal volumes and ventilatory volume
Differences in age
VO2(max) declines as we age and our body systems become less efficient
 Maximum heart rate drops by around 5-7 beats per minute per
decade
 An increase in peripheral resistance results in a decrease in maximal
stroke volume
 Blood pressure increases at rest and during exercise
 Less air is exchanged in the lungs due to a decline in vital capacity
and an increase in residual air
66
In terms of health, a good aerobic capacity is undoubtedly
beneficial. Regular aerobic training can reduce blood pressure
and lower the risk of blood clots and heart attacks
Key point
Differences in
gender and age
are two key
factors most
exam questions
focus on
67
Evaluation of aerobic capacity
There are various methods of evaluating aerobic capacity/VO2(max).
The Douglas bag is an accurate technique, carried out under laboratory
conditions. An individual runs on a treadmill to the point of exhaustion
while the air that is expired is collected in a Douglas bag. The volume
and concentration of oxygen in the expired air is measured and
compared with the percentage of oxygen in atmospheric air to see how
much oxygen has been used during the task
Another method of evaluating aerobic capacity or VO2(max) is the
multi-stage fitness test developed by the National Coaching
Foundation (NCF). An individual performs a 20m progressive shuttle run
in time with a beep, until he/she reaches complete exhaustion. The
level reached depends upon the number of shuttle runs completed and
is ascertained from a standard results table
The multi-stage fitness test gives only an estimate of VO2(max) and is
much less accurate than the Douglas bag. However, it is easy to set up
and does provide a guide from which progress can be monitored. The
equipment required is limited, making it a cheap alternative. It is also
possible to test large numbers simultaneously, so it is not as time
consuming as the Douglas bag
68
Key point Make sure you
can talk about the
advantages and
disadvantages of methods
of testing
69
Strength
Strength is the maximum force that can be exerted by a muscle or
group of muscles during a single contraction. In sport we use various
types of strength:
 Maximum strength is the maximum force a muscle is capable of
exerting in a single voluntary contraction. It is used, for example,
in weight lifting. Due to higher levels of testosterone, men have a
larger muscle mass and so can exert greater maximum strength
than women. Fast glycolytic fibres are important for maximum
strength as they can produce more force than slow-twitch fibres
 Elastic strength (power) is the ability to overcome resistance with
a high speed of contraction. This can be seen in explosive events
such as sprinting, throwing or hitting, where a high percentage of
fast glycolytic fibres is needed for a good performance
 Strength endurance is the ability of a muscle to perform repeated
contractions and withstand fatigue. It is important for rowers and
swimmers. In addition. when a team game goes into extra time,
the players with better strength endurance will be in a stronger
position to maintain a high level of performance
70
Strength decreases with age by about 1% per year. This occurs
due to a loss of mean muscle mass though a decreases in the
ability to synthesise protein
Key point Some
textbooks refer to
elastic strength as
dynamic or
explosive strength;
others call it power.
These terms are all
interchangeable
71
Evaluation of strength
One simple method of assessing maximum strength is the handgrip
test, using a muscle dynamo meter: However, it must be noted that
this test concentrates on the muscular strength of the forearm
A method of assessing elastic strength is the Wingate test, performed
under laboratory conditions on a cycle ergometer. Maximum effort is
required for a period of over 30 seconds and the number of pedal
revolutions is counted every 5 seconds of the test. A simpler test is the
vertical jump which can be performed to measure leg power. The
table below gives a rating scale for this test
Distance (cm), males
>59
51-59
41-50
<41
Distance (cm), females Rating
>46
Excellent
36-46
Good
29-35
Average
<29
Poor
A test for strength endurance assesses the ability of one or more
muscle groups to work continuously. The NCF abdominal curl test
measures the endurance of the abdominals. The test involves doing
sit-ups in time with a beat until complete exhaustion is reached
72
Key point You
need to know a
test for each type
of strength and be
able to explain
how to carry it
out. You do not
need to know the
results of the tests
73
Flexibility
Static flexibility is the range of movement around a joint, for example doing the
splits
Dynamic flexibility is the resistance of a joint to movement, for example kicking
a football without hamstring and hip-joint resistance
Many factors determine the flexibility of an individual:
 the elasticity of ligaments and tendons
 the amount of stretch allowed by surrounding muscles
 the type of joint - the knee is a hinge joint allowing movement in one plane
only (flexion and extension); a ball-and-socket Joint, such as the shoulder,
allows movement in many planes (flexion, extension, abduction, adduction,
medial and lateral rotation, circumduction)
 the structure of a joint - the hip and shoulder are ball-and-socket joints but
the hip joint has a deeper joint cavity and tighter ligaments to keep it more
stable but less mobile than the shoulder
 the temperature of surrounding muscle and connective tissue
 training - flexibility can decrease during periods of inactivity
 age - older people tend to be less flexible
 gender - women tend to be more flexible than men due to hormonal
differences
74
It is imperative for flexibility training to be carried out after
a thorough warm-up. All of the movements need to be
smooth to avoid injury and to ensure that the stretch reflex
is not triggered
Key point
Increasing
flexibility helps to
improve
performance and
avoid injury. For
example, a
footballer with
good hamstring
flexibility can
stretch that bit
further in a tackle
75
Evaluation of flexibility
The sit-and-reach test gives an
indication of flexibility
Cvcb
of the hamstrings and lower back.
To complete this test, a sit-andreach box is required
 Sit on the floor with your feet flat
against the box, legs straight
 Reach forward as far as possible,
pushing the marker with your
fingertips
 Read off your score and get a rating from tabulated values
(see
the table below)
Male
Female
Rating
>34
>38
Excellent
31-34
33-38
Good
27-30
29-32
Average
<27
<29
Poor
76
To test shoulder flexibility:
 Raise your right arm, bend the elbow, then reach down your back as
far as feels comfortable
 At the same time, bend the left elbow but with this arm reach up your
back and try to overlap the fingers of both hands
 Measure the amount of overlap in centimetres; if the fingers fail to
meet, record a minus
 Repeat the test with the left arm at the top and the right arm at the
bottom
 Record your results from a standard rating scale (see the table below)
Men
Right up
7+
6
4-5
4
Women
Left up
7+
3-6
0-2
0
Right up
8+
6-7
4-5
4
Left up
8+
3-7
0-2
0
Rating
Excellent
Good
Average
Fair
Key point The main drawback with flexibility testing is
that it measures only one muscle group
77
Body composition
This is the physiological make-up of an individual in terms of the
distribution of lean body mass and body fat. On average, men have less
body fat than women approximately 15% as opposed to 25%
Somatotyping is a classification of body shape into three categories:
 endomorph - a pear-shaped body
 mesomorph - a muscular shaped body
 ectomorph - a lean body
Body composition obviously has an important role in sport. Excess body
fat can lead to health problems, such as cardiovascular disease, and
any exercise requires greater energy expenditure as more weight has
to be moved around
It is generally agreed that the less body fat the better the
performance, although some sports have specific requirements for
larger amounts of fat, such as a defensive linesman in American
football or a prop in rugby league
In most team games, excess body fat would affect a performer's ability
to move freely around the court or field, and would increase the onset
of fatigue during a game
78
A performer with a high percentage of body fat could be at a
disadvantage in activities involving speed or vertical jumping
such as rebounds in basketball. Excess body fat can also
decrease heat loss over the skin by conduction, convection and
radiation
Key point Most
sports performers
carry less fat than the
average person
simply because fat is
a fuel used for aerobic
respiration
79
Evaluation of body composition
When assessing body composition, it is important to take into account
factors such as age, gender, adipose levels (storage of body fat),
physical activity and ethnic origin, as these can all influence the choice
of method used
Body composition can be assessed by:
 the skin fold test — skin fold callipers are used to take
measurements from one side of the body, from the biceps, triceps,
sub-scapular (below the shoulder blade) and supra iliac (hip
region). The sum of all sites is calculated and standard tables give
an indication of the percentage of body fat
 body mass index — the mass of an individual (in kilograms) divided
by his/her height (in metres)
 hydrostatic weighing — the water displaced when the body is
submerged in water
 bioeleetrical impedance — electrodes are attached at the ankles
and wrists and a small electrical current is passed through them.
Fat restricts the flow of current, so the amount of impedance gives
an estimate of body fat percentage
80
Key point The
simplest evaluative
method is the skin
fold test. Hydrostatic
weighing is only
available under
laboratory conditions
81
Agility
Agility is the ability to move and position the body quickly and effectively
while under control. The combination of speed, coordination and
flexibility is very important. For example, it is used in netball for catching
and passing on the run or in basketball for dribbling around opponents
Method of evaluation
Agility is assessed by the Illinois agility run. The performer runs around a
10m course as fast as he/she can, weaving and sprinting between a series
of four evenly spaced cones (see overleaf). The run is timed and rated by
standard tables
Males
Females
Rating
<15.3s
<17s
Excellent
15.3-16s
17-17.9s
Good
16.1-18s
18-21.7s
Average
18.1-19s
21.8-23s
Fair
>19s
>23s
Poor
Agility can be improved to some extent through various activities, but
development of this component is limited
82
Key point The
Illinois agility
run is a
recognised
national test.
More detail can
be found in
most A-level
textbooks
83
Balance
This is the ability to keep the centre of gravity over the base of
support. Balance can be static, such as in a handstand in
gymnastics, which has to be kept still, or dynamic, where balance is
retained while in motion, for example when side-stepping in rugby
to get around an opponent
To be in a balanced position, the centre of gravity needs to be in
line with the base of support. If you lower your centre of gravity,
your stability increases, while if your centre of gravity starts to
move near the edge of the base of support, you will start to
overbalance.
Method of evaluation
Balance can be assessed using a balance board
The performer stands on the board and tries to keep the sides of the
board away from the floor. The time spent
balancing is recorded and compared with
the results of other performers
It is difficult to provide specific methods of
training to improve balance, but it can be
done as part of a skills session
84
Key point another
method of
assessment is the
bench test.
Place a gym
bench upsidedown so the
beam support is
uppermost. Stand
on the beam on
one foot. Record
how long you stay on the beam. Compare your results
with others in the class and repeat the test at a later
date to see if improvement has occurred
85
Speed
This refers to how fast a person can move over a specified distance or how
quickly a body part can be put into motion. Speed is important in most
sports: a winger in rugby needs to be a fast sprinter and a pace bowler in
cricket needs to be able to move his arm quickly
Fibre type plays a major role in terms of speed. A greater number of fast
glycolytic fibres means that stimuli are received more rapidly and energy is
released anaerobically, making the performer faster than someone with a
greater number of slow-twitch fibres. The proportion of fast glycolytic
fibres is determined genetically
Method of evaluation
In the 30 m sprint test the performer runs 30 m as fast as he/she can. The
time is compared with a rating table
Males
Females
Rating
<4s
<4.5s
Excellent
4-4.2s
4.5-4.6s
Good
4.3-4.4s
4.7-4.8s
Average
4.5-4.6s
4.9-5s
Fair
>4.6s
>5s
Poor
86
Key point
Increasing speed
does nota always
result in an
improvement in
performance. It is
possible to be too
quick to the point
of making
mistakes
87
Reaction time
This is the time taken from detection of a stimulus to initiation of a
response, for example the time taken between the starting pistol going off
and movement from the blocks, or reacting to a tennis serve
Method of evaluation
Various computer tests and electrical reaction timers are available. A
simple, cheap method is the metre ruler test but this is less accurate. A
partner holds a metre ruler at the zero end. The performer places the
index finger and thumb of his preferred hand on either side of the 50cm
mark but not touching it. Without warning the partner lets go of the ruler
and the performer must close his finger and thumb to catch it. The results
can be compared with a rating table
Reaction gap (cm)
Rating
>42.4
Excellent
37-42.4
Good
29-36.9
Average
22-28.9
Fair
<22
Poor
Reaction time can be improved indirectly through skills training
88
Key point An
individual with a high
percentage of fast
twitch glycolytic fibres
has a better reaction
time because these
fibres respond more
rapidly than other
types. The speed of
conduction of nerve
impulses and the
speed of muscular contractions are both higher in this
fibre type
89
Coordination
Coordination is the ability of the motor and nervous systems to interact
so that motor tasks can be performed accurately. Examples include the
hand-eye coordination required to hit a tennis ball, and being able to
coordinate the swing of a golf club to hit the ball correctly. Speed,
precision, rhythm and fluency of execution of the skill are all important
components of coordination
Method of evaluation
An easy self-evaluation test is the alternate hand/wall ball toss. The
performer stands 2 metres from a wall with a tennis ball in her right
hand. She throws the ball underarm against the wall and catches it
with her left hand. Then she throws the bail from her left hand and
catches it with the right. The number of successful catches made in 30
seconds is recorded
There is no rating for this test but a retest can be done at a later date
to check for improvement
Coordination can be improved indirectly by learning new skills and by
performing those already learnt in a continuously changing and
competitive environment
90
Key point
You need to
be able to
define
coordination
and describe
a method of
testing it
91
Physiological adaptations to aerobic training
If you perform continuous, fartlek or aerobic interval training over a
period of time, physiological adaptations take place that make the
initial training sessions appear easy. This is because your aerobic
capacity/VO2(max) improves as the following adaptations take place:
 heart — hypertrophy of the cardiac muscle (myocardium): stroke
volume increases; maximum cardiac output increases; resting heart
rate decreases
 blood — slight increases in red blood cells and haemoglobin; blood
plasma volume increases; in addition, during maximal exercise,
blood activity increases as there is a greater tolerance to lactic
acid
 vascular system — arterial walls become more elastic; number of
capillaries in the lungs and muscles increases
 muscle — increase in size and number of mitochondria, enzyme
activity, myoglobin levels and muscle glycogen stores
 lungs — respiratory muscles become more efficient: lung volume
increases due to use of more of the available alveoli: greater tidal
volume and an increase in breathing rate lead to an increase in
maximum pulmonary ventilation
92
Key point
Physiological
adaptations are
long-lasting
changes that
occur in the
body as a result
of following a
training
programme
93
Physiological adaptations to strength training
The type of strength training determines the specific adaptations. For
example, weight training with light weights and high repetitions allows
adaptations to occur in the slow oxidative fibres: heavy weights and
low repetitions allow adaptations in the fast glycolytic fibres
Aerobic adaptations in slow oxidative fibres
Hypertrophy of the muscle fibres occurs together with an increase in
mitochondria number and myoglobin. There is an increase in glycogen
and triglyceride stores and in capillarisation surrounding the muscle
tissue
Anaerobic adaptations in fast-twitch fibres
Hypertrophy of muscle fibres occurs due to a growth in muscle cell
size, and an increase in total protein. There are also increases in ATP,
PC, glycogen stores and lactic acid tolerance
Neural adaptations
The number of motor units recruited is increased, synchronisation of
contraction is improved and the effects of the inhibition of the Golgi
tendon organ are reduced. allowing the muscle to create more force
during contraction
94
Key point Hyperplasia
theory suggests that a
muscle fibre can split and
develop two new fibres.
This is still in the early
stages of research
95
Physiological adaptations – flexibility
Most sports performers undertake flexibility training to improve the
range of motion around their joints. For example, swimmers have good
flexibility in their shoulders. which allows them to glide their arms
through the water using shoulder elevation, easily accommodating the
required joint angles without placing stress on the surrounding tissues
Adaptation to flexibility training is one of the least understood areas of
sports science research. Some argue that flexibility training can cause
the tendons, ligaments and muscles surrounding a joint to increase
their resting length due to greater elasticity. Others argue that longterm adaptation to a regular, static, stretching training programme
increases the stretch tolerance (the ability to withstand the force of
the stretch) This is because the muscle spindle can become used to the
increase in length caused by the stretch and reduce the stimulus to the
stretch reflex, which when activated will work to prevent elongation of
the muscle being stretched. This means the muscle can stretch further.
Most of this increase occurs in muscle tissue rather than connective
tissue
With regular ballistic stretching, the nervous system learns to
accommodate by delaying the stretch reflex until near the end of the
range of movement
96
If the change in length is temporary (after a warm-up), it is
referred to as an elastic change. If it is permanent (following
a period of flexibility training), it is known as a plastic
change
Key point An
increase in flexibility
can help in the
prevention of injury
and in recovery. It
can lead to
improvement in
posture and may
improve motor
performance and
skill execution through a better range of movement
around the joints
97
Ergogenic aids (legal)
Method of enhancement
High carbohydrate diet –
increased intake of pasta,
rice, bread etc
Glycogen loading (see
slide 19)
Caffeine – stimulant
Creatine monohydrate –
used to increase
phosphocreatine stores in
the muscles
Reasons used
Compensates for lower
levels of glycogen during
exercise
Raises glycogen levels
and hence increases
endurance performance
Thought to improve the
mobilisation of fatty acids
in the body
Allows the ATP-PC
system to last longer and
can improve recovery time
Side effects
None
More water stored in the
muscle; possible
psychological problems
Increased danger of
dehydration
No harmful side effects
known
98
With the huge demands and expectations placed on top sports
performers, together with the extrinsic rewards that can be
gained for winning, it is understandable why the use of legal
ergogenic aids is important. Anything that can help in the
pursuit of excellence needs to be considered
Key point ‘Ergogenic’
refers to anything that
improves performance
99
Ergogenic aids (illegal)
Method of enhancement
Anabolic steroids
Beta blockers
EPO – hormone that
increases red blood cell
count
Blood doping – blood is
removed and stored; body
makes more red blood
cells to compensate;
stored blood is then
injected back
Amphetamines –
stimulants
Reasons used
Promote muscle growth
and lean body weight
Can improve accuracy in
precision sports by slowing
the heartbeat
Improve aerobic capacity
by increasing the oxygencarrying capacity of the
blood; this allows the
performer to work for
longer
Side effects
Liver damage; acne;
excessive aggression
Tiredness
Decrease tiredness;
increase metabolism
Insomnia; weight loss;
cardio-vascular problems
Increased viscosity of the
blood could lead to clotting
and a risk of stroke or
death
100
Key point Unfortunately,
the use of illegal
ergogenic aids is more
prevalent than ever,
despite increasingly
sophisticated drug-testing
methods. The use of such
performance- enhancing
drugs is not a new
phenomenon. It can be
traced back through history. For example, the Ancient
Greek Olympians supposedly ate ergogenic mushrooms,
while in the late 1800s cyclists were known to take heroin
and cocaine