Download At the 2008 Beijing Olympic Games, David Davies won the silver

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 ATP
Objective:
To be able to explain how energy is produced during initial
exercise and particularly at high intensity.
* 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:
1.
2.
Phosphocreatine (PC) energy system (or ATP-PC system)
Lactate anaerobic energy system
Anaerobic energy systems
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).
* 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!).
* Lactic acid 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 systems
* 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 lactic
acid.
* The build up in lactate acid 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.
Lactic acid is often seen as a ‘waste product’ but can be a useful
energy source. During recovery from intense exercise (when O2 is
available) lactic acid 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 urine
Objective: To be able to define lactate threshold and
OBLA, and the effect on performance.
* Onset of blood lactic acid accumulation (OBLA) is the point at
which lactic acid starts to accumulate in the blood (above 4
mmol per litre).
* This occurs when there is insufficient O2 available to break down
lactic acid.
* As exercise intensity increases, O2 consumption increases until
VO2 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.
*
There are three energy systems that can regenerate ATP:
* the ATP–PC system (anaerobic)
* the lactic acid 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 lactic acid
system
* If the activity is long duration and submaximal pace, we use the
aerobic system.
* 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 fitness
*
*
Muscle fatigue is the inability to maintain muscle contractions.
There are numerous causes including:
* An increasingly acidic environment caused by the build up of
lactic acid and 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.).
*
* 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 VO2 max (higher intensity) before
crossing the lactate threshold (and moving to anaerobic energy
systems).
The Brownlee Brothers
* “he sprinted away for victory”
* “you have to race the
conditions”
* “It was hot. I just made sure I
took on plenty of water”
* “I wish the flipping idiot had
just paced it, he could have
jogged and won”
* “I was happy with 2nd or 3rd so
I took it easy”
* An increasingly acidic
environment caused by the
build up of lactic acid and
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.).
*
* The ability to withstand the effects of lactic acid
accumulation.
* This may be related to the amounts of bicarbonate in the
blood (which can combine with lactic acid to reduce its
acidity).
* May just be down to motivation/determination levels.
*
To recover from intense exercise the body needs to:
* Restore ATP levels
* Restore phosphocreatine levels
* Deal with excess lactic acid (either by oxidating lactic acid into
pyruvate, or by converting lactic acid into glycogen in the liver –
both are eventually used to create ATP)
* Resaturating myoglobin with oxygen
* Restoring muscle glycogen levels (high carb diet)
Energy System
Fuel Used
ATP-PC
ATP
PC
Lactic Acid
(Anaerobic
Glycolysis)
Glycogen /
Glucose
Aerobic
(Glycolysis)
Carbohydrates
Fats
Proteins
(extreme
circumstances)
Intensity /
Duration
Contribution
Sporting
Examples
High / Short
Up to 10s
(approx)
Diving
Gym vault
100m sprint
High Intensity
10s – 3mins
Short – Moderate
Duration
Depending on
intensity
Submaximal
Extended
Peak efficiency
achieved in 1-2
mins. Dominant
system when HR
<85%
200m sprint
400m sprint
50m swim
1500m
Marathon
Triathlon
*
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;
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)
*
Elite games players require high levels of fitness and psychological
preparation, therefore regular fitness testing and after-match
performance
analysis are common.
Figure 1 illustrates the relationship between the concentration of blood
lactate and the workload.
a) Use Figure 1 to identify the workload level at which lactate threshold
occurs, and explain why lactate (lactic acid) tends to be produced when a
player is exercising. (3 marks)
(b) Explain how lactate is removed from the blood by the body. (4 marks)
a)
1.Lactate threshold correctly identified as between 500 and 800 Watts;
2. Lactate from anaerobic (glycolosis)/lack of oxygen (O2)/high
demand/lack of supply;
3. High intensity/workload exercise/equiv.
b)
1 Used as respiratory substrate/for respiration / energy / using oxygen
(O2)/ lactate to replenish ATP;
2 Converted to pyruvate/pyruvic acid;
3 then to Carbon Dioxide (CO2) and water;
4 In inactive muscle and various tissues/organs;
5 Converted to glycogen/glucose;
6 In liver;
7 Some excreted in sweat/urine/conversion to protein