E xplain the factors that contribute to a performers VO2 max 7 marks VO2 max definition maximum volume of oxygen that can be utilised per minuteunit of time Relative VO2 max definition takes into account body weight mlkg1min1 ID: 200314
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Slide1
Energy SystemsSlide2
Adenosine Triphosphate (ATP)
Our body uses ATP to produce energy.
The
body transforms the food we eat into ATP
.
When ATP is broken down it releases ADP + P + energy
.
The body can
resynthesise
ATP by the reverse reaction: ADP + P + energy = ATP
.
The body cannot store much ATP (only enough for about 2-3s of intense activity) so any energy required needs to be produced immediately
.Slide3
Sources of Energy
ATP can be
resynthesised
from the breakdown of carbohydrates (into glucose), fats (into fatty acids and glycerol), and protein (into amino acids
).
E
xcess
glucose
is
stored
as glycogen in
the muscles and
liver.
Glycerol can be converted into glucose when glycogen stores have been depleted (e.g. marathon
).
At rest most of our energy comes from fats, during exercise energy is mostly supplied from carbohydrates.Slide4
Energy Systems
There are 3 energy systems:
The aerobic system
This is the primary energy system for endurance events. It produces lots of ATP and no fatiguing by-products but it cannot produce energy quickly.
The lactate system
This is the primary energy system for middle distance events. ATP is produced quite quickly but there is a harmful by-product.
The ATP-PC system
This system produces energy extremely quickly but can only fuel around 10 seconds of activity.Slide5
Aerobic Energy Production from Glucose
When oxygen is present
glucose can be broken down completely.
This occurs in the mitochondria and produces CO2, H2O, and
energy
(ATP).
The advantages of aerobic energy production is that there are no fatiguing by-products, the energy sources are usually abundant and lots of ATP can be produced
.
The breakdown of glucose into energy (ATP) involves 3 stages:
Glycolysis
, Kreb’s cycle, and the
Electron Transport Chain
.Slide6
Glycolysis
The initial stage of glucose breakdown
.
This stage is identical in both the aerobic and anaerobic
systems.
Some
complicated reactions take place but
the basics you
need to know
are….
Pyruvic acid is produced (pyruvate
).2 ATP are used and 4 ATP produced, so there is a net gain of 2 ATP during this stage.As well as ATP we also gain NADH, which becomes important at a later stage (Electron Transport Chain).Slide7
Kreb’s Cycle
This follow’s on from
glycolysis, using the products from Glycolysis.
It only
occurs in the presence of oxygen
.
The pyruvic
acid from glycolysis is added to coenzyme
A, producing
A
cetyl Coenzyme
A in preparation for the Kreb’s Cycle.At this stage we gain another NADH for each Acetyl Coenzyme A.Again, lots of complicated reactions take place but all that you need to know is that 2 ATP are produced.In the Krebs cycle we also gain a further 6NADH and 2FADH
2Slide8
Electron Transport Chain
The final stage of glucose breakdown
.
Once again, numerous complicated chemical reactions take place but all that you need to know is;
Large
amounts of oxygen are required at this stage (thus it is aerobic energy production
).
The NADH and FADH2 from previous stages are utilised here.
34
ATP molecules are produced
.
So, at the end of these 3 stages 40 molecules of ATP are produced and 2 are used (net production = 38 ATP).Slide9
GLYCOLYSIS
2ATP are used to split glucose into two 3-carbon molecules.
For each of the 3-carbon molecules, 2ATP and 1NADH are produced when forming pyruvic acid.
KREBS CYCLE
Pyruvic acid is not able to enter the Krebs Cycle, so coenzyme A is added to form acetyl
coenzymeA
.
For
each
acetyl
coA
that enters the Krebs Cycle 1ATP, 3NADH and 1FADH2 are produced.ELECTRON TRANSPORT CHAINThe NADH and FADH2 molecules produced during Glycolysis and the Krebs Cycle enter the Electron Transport Chain, yielding 34ATP.Slide10
Aerobic Energy Production from Fat
Fatty acids are broken down by a process called beta-oxidation to acetyl CoA which enters the
Kreb’s
cycle (and eventually electron transport chain
).
M
ore
ATP can
be produced
from fat than from glucose (during electron transport chain) but far more O
2
is required.Fat is therefore an excellent energy source at rest or low intensity exercise but cannot be used during high intensity exercise when a lack of O2 becomes a limiting factor.Slide11
Effects of Training on Aerobic Energy Systems
Cardiac hypertrophy and increased resting stroke volume (SV
).
Decreased resting HR
.
Increased muscle stores of glycogen and triglycerides
.
Increased
capilliarisation
of
muscle and increased number and size of mitochondria.More efficient transport and effective use of O2 means that fat is used more during exercise (carbs saved for higher intensity).
Maximal oxygen
consumption
(V0
2
max)
increases
.Slide12
Oxygen Consumption (VO
2
)
The amount of oxygen used by our body is called oxygen consumption
.
During exercise we need more ATP so O
2
consumption increases
.
Often when we begin exercise there is insufficient O
2
available to produce ATP aerobically as it takes time for the body to adjust.When 02 consumed is lower than 02 used, there is an ‘oxygen deficit’.O2 consumption increases with exercise intensity until the point of max O
2
consumption (VO
2
max).Slide13
VO
2
Max
VO
2
max is the maximum amount of O
2
that the body can consume and use
.
A higher VO
2
max means a higher level of aerobic fitness.If exercise intensity is submaximal (below VO2 max) then O2 consumption reaches a ‘steady state.’ – O2 consumption matches O2
required
.
VO
2
max can be assessed
by measuring
amount of O
2
consumed in comparison
to amount
of CO
2
breathed out
during exercise with ever increasing intensity.Slide14
Factors affecting VO
2
Max
VO
2
max is the body’s ability to get O
2
to the lungs, transfer it to the blood, transport it to muscle cells and mitochondria, and use the O
2
in energy processes.
It is dependant on:
The surface area of alveoli (genetically determined)Red blood cell and haemoglobin levelsThe capillary density in the lungsThe efficiency of the heart and circulatory systemThe capillary density in muscle cellsThe transfer of O2 to mitochondria via myoglobinThe take-up and use of O2 by mitochondriaSlide15
Exam Question
Describe the changes that occur in the body to make the aerobic energy systems more efficient following prolonged endurance training. (4 marks)
Cardiac
hypertrophy – larger heart creates a stronger contraction (pump).
Increased resting stroke
volume – volume of blood leaving the left ventricle per beat.
Decreased resting heart
rate – number of beats per minute at rest.
Increased blood volume and haemoglobin
levels – higher volume of oxygen able to be transported at one time.
Increased muscle glycogen
stores – greater amount of glucose available for energy production from converted glycogen.
Increased myoglobin content in
muscles – greater initial receptors of oxygen from the circulatory system before it is transported to the mitochondria.
Increased
capilliarisation
of
muscle – more O2 can be diffused into working muscle from circulatory system.
Increased number and size of
mitochondria – more ATP can be resynthesized in the muscle cell.
Resulting increase in VO2 max
overall (maximal
oxygen consumption
).Slide16
O
2
Consumption – Rest & ExerciseSlide17
Post Exercise
Following exercise, bodily processes do not immediately return to resting levels, especially after intense exercise.
Consuming O
2
at higher than resting levels after exercise is
called
Excess Post-exercise
O
xygen
C
onsumption
(EPOC). There are 2 components:Fast (alactacid) component
O
2
used to
resynthesise
ATP and phosphocreatine levels,
re-saturates
myoglobin (which transports O
2
from blood to muscle fibres). This component will be very short after highly aerobic exercise
.
Slow (
lactacid
)
component
O2 used to remove lactate and excess H ions.Slide18
EPOC
During the
alactacid
(fast) component 75% of PC stores are restored within 1min and nearly 100% in 4mins. It takes 2mins to reload myoglobin with oxygen.
The removal of lactic acid (slow component) can take up to several hours.
As O
2
is vital during these processes it is essential to perform a cool
down – breathing rate/heart rate is raised slightly above resting level to ensure more oxygen is provided.
Fitness levels along with exercise intensity levels determine the duration of EPOC.Slide19
EIMD & DOMS
Exercise induced muscle damage (EIMD)
Delayed onset of muscle soreness (DOMS) is a symptom of this.
EIMD is most severe during different or high intensity training (this is why overload is a key principle of training)
One reason these is damage to the sarcomeres (actin/myosin filaments). Protein intake in the 2-hour window of opportunity helps minimise this.
Glucose depletion is also a contributing factor so a high carb diet is important.
Does muscle soreness mean that training is working?Slide20
Exam Question
During recovery from exercise, Excess Post-exercise Oxygen Consumption (EPOC) occurs. Explain the differing functions of the fast and the slow components of EPOC, and how EPOC varies with intensity of exercise. (7 marks)
Fast component -
resynthesis
of ATP / PC levels;
Alactacid
component
Resaturation
of myoglobin with oxygen
75% PC restored within one min, 100% within 4
mins
;Slow component - removal of lactate / lactic acid;By oxidation / energy production;Conversion to replenishment of glycogen (glucose) by reconverting lactic acid into pyruvate and continuing through the aerobic processes of Kreb’s cycle and electron transport chain;
Some converted to protein / some excreted in sweat and / or urine;
Oxygen used to maintain high work rates of heart / breathing muscles;
Extra oxygen used as temperature remains high;
More recovery time with higher intensities;
Greater oxygen consumption with higher intensity;
EPOC is
larger
with higher intensity
.Slide21
At the 2008 Beijing Olympic Games, David Davies won the silver medal in the swimming 10 kilometre marathon event, in a time of 1 hour 51 minutes and 53.1 seconds.
Explain how the majority of energy used during the race would be provided. (7 marks)
A. Majority produced by the aerobic system/oxygen
B. Glycolysis/Anaerobic glycolysis
C. Carbohydrates/glycogen/glucose
D. broken down into pyruvate/ pyruvic acid
E. Some ATP produced/2 ATP
F. Krebs cycle
G. Fats/triglycerides/fatty acids/glycerol
H. Beta oxidation
I. Oxidation of acetyl-coenzyme-A/Citric acid/ production of CO2
J. Electron transport chain
K. Water/H2O formed/hydrogen ions formed (H+)/ hydrogen/protons
L. Large quantities of ATP produced or
resynthesised
/34- 36 ATPSlide22
Figure
4 shows the effects of daily 10-mile runs on the concentration levels of glycogen
in muscles
.
(a) Explain
what Figure 4 shows, and briefly explain the role of glycogen in
endurance performance.
(
4 marks
)
(b) How could elite endurance performers try to artificially increase their glycogen stores in
an attempt
to improve performance
?
(
2
marks
)
Exam QuestionSlide23
a)
Shows
that levels of stored glycogen are depleted during 10 mile run;
Limited glycogen stores;
1 day / 24 hours insufficient time for complete replenishment / equivalent;
Lack of glycogen causes fatigue or deterioration in performance;
Provides energy (store);
For ATP
resynthesis
;
Through oxidation / aerobic;
(b) Either –1 Dietary manipulation – (3-4 days) prior to competition ingest no carbohydrates;2 (Day) before competition – high carbohydrate diet, e.g. pasta / carbo loading;Or –3 Exercise plus diet – 4-6 days prior to competition take exhausting run;
4 Maintain low carbohydrate diet until day before competition – then
carbo
load;
Or -
5 Reduce intensity of training leading up to event;
6 Maintain high carbohydrate diet.
Mark SchemeSlide24
Anaerobic Energy Systems
When the body is unable to provide the oxygen required to
resynthesise
ATP it must start to work anaerobically.
There are two anaerobic energy systems:
Phosphocreatine (PC) energy system (or ATP-PC system)
Lactate anaerobic energy system
Anaerobic energy systemsSlide25
Phosphocreatine (PC) Energy
S
ystem
(or ATP-PC system)
PC → P + C + Energy AND Energy + P + ADP = ATP
For every molecule of PC broken down, one molecule of ATP can be
resynthesised
.
No oxygen is required.
Energy is released very rapidly and there are no waste products.
Stores only last for 5-8s of high intensity exercise.
It is therefore excellent for very high short intensity activities (e.g. 100m sprint) but not for anything longer.
PC can be
resynthesised
quickly. 50% in 30s, 100% in less than 4
mins
(this requires O2 so intensity must be reduced).Slide26
Lactate Anaerobic
E
nergy
S
ystem
This system involves the partial breakdown of glucose (oxygen is required for full breakdown).
2 molecules of ATP are produced for every molecule of glucose (19 times less than aerobic!).
Lactate is produced as a by-product.
This system can therefore only be sustained for between 10 seconds and 3
mins
.
Few chemical reactions involved so energy can be produced quickly.summary of anaerobic energy systemsSlide27
Lactate
Hydrogen
is released during both glycolysis and the
Kreb’s
cycle.
These H ions combine with oxygen (in the electron transport chain).
At some point there becomes too many H ions for the amount of
O2
available. Excess H ions combine with pyruvate to form
lactate.
If high intensity exercise continues then excess H ions continue to build up. This is
a contributing factor for fatigue. It produces an acidic environment which slows down enzyme activity and stops the breakdown of glucose. It also effects nerve endings causing some pain.Slide28
Lactate and Lactic Acid
These terms are often used interchangeably but are actually different things.
Lactate is produced by the body during anaerobic exercise. It is not a negative by-product and actually helps to provide the body with energy.
Lactic acid is a slightly different substance and isn’t actually produced by the body.
That said, you can probably use either term although lactate is technically correct.Slide29
What happens to Lactate?
Lactate is often seen as a ‘waste product’ but can be a useful energy source. During recovery from intense exercise (when O2 is available) lactate can take the following routes:
1
. conversion to water and carbon
dioxide (after being converted back to pyruvate and entering the
Kreb’s
cycle)
2. conversion into
glycogen and stored in liver / muscles
3. conversion into protein
4. conversion into glucose
5. conversion into sweat and urineSlide30
Lactate Threshold / OBLA
Onset of blood lactate accumulation (OBLA) is the point at which lactate starts to accumulate in the blood (above 4
mmol
per litre).
This occurs when there is insufficient O
2
available to break down lactate.
As exercise intensity increases, O
2
consumption increases until VO
2
max is reached. Any increase in intensity will then cross the lactate threshold.Predominantly aerobic ATP resynthesis switches to anaerobic when there is insufficient oxygen in the mitochondria to combine with the H released when glucose is broken down.OBLA shows fitness levels as the longer a performer can hold off lactate accumulation, the fitter they are.Slide31Slide32
100m Sprinting
It is often said that the winner of a 100m race is the person who slows down the least. Is this true?
Usain Bolt 100m world record
50-60m 0.82 seconds
60-70m
0.82 seconds
70-80m
0.82 seconds
80-90m 0.83
seconds
90-100m 0.90
secondsSlide33
Energy System Continuum
There are three energy systems that can regenerate ATP:
the ATP–PC system (anaerobic)
the
lactate
system (anaerobic)
the aerobic
system
The use of each of these systems depends on the intensity and duration of the activity:
If the activity is short duration (less than 10 seconds) and high intensity, we use the ATP–PC system.
If the activity is longer than 10 seconds and up to
3 minutes at high intensity, we use the lactate systemIf the activity is long duration and submaximal pace, we use the aerobic system.Slide34
Which energy system?Slide35
Aerobic or Anaerobic?
During nearly all activities both systems will be involved at the same time, the one which is more predominant depends on:
The level of intensity
The duration
Your level of fitnessSlide36
Energy Continuum
It is the duration of the activity not the distance covered which determines the energy sources. E.g. Mo Farah can run 3000m in 7.30mins. Another person may take that long to run 1500m. They would both be using a similar percentage of aerobic / anaerobic energy.
Distance
200
400
800
1500
5000
10000
Time
22
49
1m53
3m55
14m00
30m00
% aerobic
% anaerobicSlide37
Think about the tactics involved in races such as 5000m.
Mo Farah 5000m last race
The percentage of aerobic/anaerobic is dependant on how quickly the race is run. E.g. a 200m race could be sprinted anaerobically or jogged aerobically.
Distance
200
400
800
1500
5000
10000
Time
22
49
1m53
3m55
14m00
30m00
% aerobic
29
43
66
84
95
97
% anaerobic
71
56
34
16
53Slide38
A = ATP-PC System
B =
Lactiate
Energy System
C = Aerobic Energy SystemSlide39
Fatigue
Muscle fatigue is the inability to maintain muscle contractions. There are numerous causes including:
An increasingly acidic environment caused by the build up of excess H ions results in a breakdown in chemical reactions.
Glucose stores being depleted.
A change in the balance of chemicals that instigate muscle contraction.
Dehydration causing increased blood viscosity (leading to increased HR, overheating etc.).
Damage to muscle fibres (micro tears)Slide40
Lactate Threshold / VO
2
Max and Exercise
When an athlete crosses their lactate threshold fatigue will quickly set in.
Pacing themselves to work near, but not over, their lactate threshold is key to success in endurance events.
As an individual becomes fitter they will be able to work at a higher percentage of their VO
2
max (higher intensity) before crossing the lactate threshold (and moving to anaerobic energy systems).
The Brownlee
BrothersSlide41
Lactate Tolerance
The ability to withstand the effects of lactate accumulation.
This may be related to the amounts of bicarbonate in the blood (which can combine with lactate to reduce its acidity).
May just be down to motivation/determination levels.Slide42Slide43
Energy
System
Fuel Used
Intensity
/ Duration
Contribution
Sporting Examples
ATP-PC
ATP
PC
High / Short
Up
to 10s
(
approx
)
Diving
Gym
vault
100m sprint
Lactic
Acid
(Anaerobic Glycolysis)
Glycogen / Glucose
High Intensity
Short –
Moderate Duration
10s
– 3minsDepending on intensity200m sprint400m sprint50m swim
Aerobic(Glycolysis)CarbohydratesFatsProteins (extreme circumstances)
Submaximal
Extended
Peak efficiency achieved in 1-2
mins
. Dominant
system when HR <85%
1500m
Marathon
TriathlonSlide44
Exam Question
Many
elite swimmers use blood lactate sampling during training as a means of
establishing their
training load.
(
i
) What do you understand by the term lactate threshold
? (
2 marks)
(ii) How is lactate threshold related to VO2 max?
(2 marks)(iii) Explain how knowing blood lactate levels during a swim might assist an elite performer. (2 marks)i)
1
Exercise has become
anaerobic;
2
Lactic acid
accumulates in
blood;
3
4
mmol
/L of
blood.
(
ii) 1 Lactate threshold is some proportion/percentage of VO2 max;
2 Proportion/percentage increases as fitness increases. (iii) 1 Accurately measures intensity of training; 2 Elite performers need to train close to their Lactate threshold/VO2 max;Slide45
EXAM QUESTION
Successful track and field performance is dependent upon an effective energy supply. Figure 3 shows how the supply of each energy system varies according to the duration of a task
.
1. Identify each of the energy systems A, B and C. (2 marks)
2. Explain how the differing energy sources of these systems are used during:
(
i
) a series of javelin throws; (2 marks)
(ii) a long-distance run of increasing intensity. (4 marks)Slide46
Different Forms of Energy
Discuss with the person next to you – how many different forms of energy can you name?
Mechanical energy
Electrical energy
Potential energy
Chemical energy
Kinetic energySlide47
Electrical energy – the energy in electrical charges
Potential
energy – the energy possessed by an object because of its position
Chemical
energy – the energy stored in food
Kinetic
energy – the energy in moving objects (also called movement energy)
Mechanical
energy – the sum of potential energy and kinetic energySlide48
The hammer has potential energy but no kinetic energy.
Lifting the hammer up increases its potential energy.
The force applied to the hammer gives it kinetic energy. The sum of the potential and kinetic energy is mechanical energy which is the force applied to the nail.Slide49
Energy
Messages sent around the body are in the form of electrical energy.
When a message travels along a motor neurone it changes to chemical energy as it passes across the synaptic cleft