Download Fatigue and the recovery process

SECTION 3.1 –
CHAPTER 4
ANSWERS TO QUESTIONS
CHAPTER 4: Fatigue and the recovery process
Text between pages 43 to 47, answers to questions on pages 47 to 48 of the text book.
1) a) What is muscle fatigue?2 marks
Answer
• The inability of a muscle to maintain its strength of contraction or tension.
• So that the strength of contraction becomes progressively weaker.
• Until the muscle no longer responds.
b) Describe the possible causes of fatigue during maximal exercise lasting 2 to 10 seconds.3 marks
Answer
• Depletion of PC stores.
• Lack of O2.
• Neural fatigue or decrease in neural activity.
2) During intense exercise, athletes can experience a large increase in lactic acid.
a) Explain the effect of lactic acid build up on muscle function.4 marks
Answer
• Accumulation of lactic acid in muscle cells causes extreme fatigue and complete loss of muscle function.
• This is because an increase in hydrogen ions (H+ - generated from the lactic acid build up).
• Causes a decrease in pH (called blood acidosis).
• Which inhibits both anaerobic and aerobic enzymes required for ATP regeneration.
• Thereby inhibiting the contractile processes (i.e the ratchet mechanism which brings together the actin and myosin filaments) of
the muscle cell.
• Thus leading to muscle fatigue.
b) Suggest strategies that athletes could use to increase their tolerance to lactic acid.4 marks
Answer
Bicarbonate loading:
• By ingesting bicarbonate, prior to a competition, an athlete can increase plasma bicarbonate levels that provide additional buffering
capacity.
• Thus allowing higher concentrations of lactate in the blood.
• Theoretically, this could delay the onset of fatigue in all-out anaerobic activity, such as in a 400 metre race.
Training:
.
• Elite endurance athletes may not reach. their lactate threshold until 70% to 80% of their VO2max.
• Endurance training based on 80% of VO2max, will increase tolerance to lactic acid.
• And so delay the lactic acid threshold even further.
• Anaerobic interval training studies have shown that 30 second bouts of high intensity interval exercise increase the activities of
glycolytic enzymes, such as phosphorylase, phosphofructokinase and lactate dehydrogenase from around 10% to 25%.
• This increase in glycolytic capacity will allow the muscle to develop greater tension for a longer period of time.
• As the muscle tissue increases its tolerance to lactate.
• Economy of effort occurs as the athlete becomes more skilful.
• Therefore, there will be decrease in energy demands, thereby delaying the lactate threshold.
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SHORT-TERM PREPARATION
c) Describe the possible causes of fatigue during submaximal exercise lasting between 2 to 4 hours.4 marks
Answer
• Depletion of muscle and liver glycogen stores.
• Gradual build up of lactic acid.
• Blood acidosis or a fall in muscle pH inhibits enzyme action.
• Build up of H+ ions and increases in ADP affect ionic balance of cell membrane wall.
• All this inhibits the contractile processes.
• Neural fatigue, such as failure to stimulate an action potential to cross from the motor neurone to muscle fibre.
• Muscle sheath or fibre damage due to repetitive trauma.
• Fluid loss due to sweating will decrease plasma volume.
• Which reduces blood pressure and peripheral blood blow.
• This means that the heart has to work harder, body temperature rises and fatigue occurs (called the cardiovascular drift).
• Psychological fatigue, which suggests that fatigue is a perception of the mind.
3) What is meant by the Central Governor Theory and how is it related to fatigue?4 marks
Answer
• This theory outlines a possible psychological element to fatigue.
• It states that fatigue is a perception.
• And an emotional response to situations, such as muscle fatigue.
• The situation is paced by the brain.
• And so the brain decides the time to quit.
4) Explain why cool-down is important within an exercise regime.4 marks
Answer
Cool-down:
• Continued low level exercise and stretching keeps the capillary beds open within active (muscle) tissue.
• This avoids blood pooling (blood is stored in the venous system as a reservoir until muscle contractions force it back towards the
heart).
• This enables the flushing out of waste products such as lactic acid from the metabolic processes.
• Enabling the body’s systems to gradually return to its resting state.
• Which limits muscle soreness (DOMS).
• And enhances recovery from the exercise period.
5) a) State where and in what conditions lactic acid is commonly found in relatively large amounts.2 marks
Answer
• Conditions for lactic acid are anaerobic.
• Lactic acid is found in (muscle cell) sarcoplasm.
b) There are several ways by which lactic acid can be removed from active muscles. Identify the major pathway for the removal of lactic acid and the organs and tissues involved.4 marks
Answer
2 marks for:
• Lactic acid is converted back to pyruvic acid.
• And the majority of lactate is oxidised within cell mitochondria - i.e. the aerobic energy system pathway.
2 marks for two of organs and tissues which are involved in the removal of lactic acid:
• Oxidation occurs in slow twitch muscle fibres (once sufficient O2 is available).
• Blood transports lactic acid (for oxidation) to other organs, which have not been operating under anaerobic conditions.
• Such as liver, kidneys, brain, heart.
c) Identify the three other ways, with approximate percentages, in which lactic acid is disposed of in the body.
3 marks
Answer
• Converted to glycogen – 20%.
• Converted to protein – 10%.
• Converted to glucose – 5% (lactate shuttle).
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CHAPTER 4
ANSWERS TO QUESTIONS
VO 2
d) How does light exercise influence lactate removal?3 marks
Answer
• Light exercise keeps blood capillaries dilated.
• Avoids blood pooling.
• Flushing oxygenated blood through the muscle.
• Increasing the oxidation of lactic acid and removing lactate from the muscle cells.
figure 4.10 – oxygen consumption
during exercise and recovery
6) Figure 4.10 shows oxygen uptake of an elite games player undertaking exercise
followed by a recovery period.
a) Using the appropriate letters, identify the oxygen deficit and Excess Post Oxygen E
Consumption (EPOC). 3 marks
Answer
• Oxygen deficit = E.
C
A
• EPOC = A and D.
b) Why does the elite player incur an oxygen deficit during exercise?
2 marks
Answer
• The oxygen deficit represents the difference between
the oxygen required during the exercise.
• And the oxygen actually consumed during the activity.
D
resting O 2
consumption
rest
exercise
B
recovery
time
c) Excess Post Oxygen Consumption (EPOC) is considered to have two components. State two aims of the first component and explain how this component is achieved.4 marks
Answer
1 mark for one of:
• The first component is called the alactacid component and involves the restoration of muscle phosphagen.
• So that exercise can begin again within 3 minutes of recovery time.
3 marks for explanation:
• This component involves the conversion of ADP back to PC and ATP.
• Firstly, there is aerobic conversion of carbohydrates into CO2 and H2O to resynthesise ATP from ADP and Pi.
• Then some of the ATP is immediately utilised to create PC using the coupled reaction: ATP + C è ADP + PC.
d) Describe the process of ATP production that restores the oxygen debt or EPOC.6 marks
Answer
Description or equivalent diagram:
• Stage 1 = glycolysis in sarcoplasm.
• Energy yield 2ATPs per molecule of glucose.
• Stage 2 = Kreb’s cycle in cell mitochondria.
• In presence of oxygen (O2).
• Yields 2ATPs per molecule of glucose.
• And carbon dioxide (CO2) .
• Releases H+ and e- into next stage.
• Stage 3 = Electron transport stage.
• In inner cristae of mitochondria.
• Oxygen used to create ATP as H+ and e- meet.
• With water (H20) given off.
• Creates 32/34 ATPs per molecule of glucose.
e) Explain why oxygen consumption remains above resting levels after exercise has finished.3 marks
Answer
• Oxygen is required to replenish PC stores.
• Oxygen is required to resaturate myoglobin.
• Oxygen is required to remove lactic acid.
• Oxygen is required to restore elevated body temperature, breathing rate and heart rate to pre-exercise values.
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SHORT-TERM PREPARATION
7) An elite games’ player performs an interval training session during which the rate of muscle phosphagen levels during the
recovery period was recorded. The results from this training session are given in Table 4.2.
a) Using the results in Table 4.2, plot a graph of recovery time against the percentage of muscle phosphagen restored.
3 marks
Table 4.2 – muscle phosphagen during recovery
Answer
• See figure Q4.1.
recovery time / s muscle phosphagen restored / %
10
30
50
60
75
90
87
120
93
150
97
180
99
210
101
240
102
figure Q4.1 – phosphagen recovery
% muscle phosphagen restored
10
100%
100
80%
80
60%
60
40%
40
20%
20
00%
00
50
50
100
100
150
150
200
200
250
250
recovery time / s
b) What resting value would you recommend for a full recovery, and what would be the effect of restarting the exercise after 30 seconds? 2 marks
Answer
1 mark for resting value:
• 180-210 seconds needed for full recovery.
1 mark for the effect of restarting exercise:
• 50% of muscle phosphagen would have been restored.
• Or 50% muscle phosphagen would have been depleted.
c) Part of the recovery mechanism after anaerobic exercise involves myoglobin. Explain the function of myoglobin during the recovery process.3 marks
Answer
• Myoglobin is an iron protein molecule located within skeletal muscle.
• Structure is similar to haemoglobin.
• Myoglobin facilitates transportation of O2 from HbO2.
• Into the muscle cell or the mitochondria.
• It acts as a temporary storage site for O2.
8) How could information on oxygen debt recovery be of use to an athlete and coach in designing training sessions?
5 marks
Answer
2 marks for two of:
• Recovery of the phosphagens (PC) is rapid - maximum 2 minutes.
• Therefore athlete is able to perform many repetitions of high quality of short duration i.e. between 8-10 seconds maximal exercise.
• Build up of lactic acid inhibits enzyme activity and performance deteriorates.
• EPOC removes lactic acid.
• Removal of lactic acid relies on the limited buffering capacity of muscle tissue.
• And much larger buffering capacity of the hydrogencarbonate ion.
3 marks for three of implications for training sessions:
• Athlete must have adequate rest relief between repetitions.
• Use active recovery between repetitions, and cool-down to facilitate the removal of lactate.
• Variation of workload from one session to the next.
• For example, one high intensity session where the lactic acid system is stressed.
• Followed by a moderately intense aerobic or anaerobic (ATP-PC system) session.
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ANSWERS TO QUESTIONS
9) After a particularly strenuous weight training session, a shot putter may experience muscle soreness immediately after the
session and the following day. Explain the reasons for this during both these times and identify strategies that could be used
to keep the pain to a minimum.8 marks
Answer
2 marks for immediately after the session:
• Muscle or connective tissue damage.
• Acute muscle soreness (at end or immediately after exercise).
• Accumulation of the end products of exercise namely lactic acid or lactate and creating H+ or hydrogen ions.
• Reduced pH level/increased acidity (acting on the pain receptors).
• Tissue oedema/fluid shifts from blood plasma to damaged tissues (stimulating pain receptors).
2 marks for the following day:
• Delayed onset muscle soreness (DOMS) (24-48 hours after exercise).
• Results primarily from eccentric muscle contractions/plyometric work.
• Which places excessive mechanical forces on skeletal muscle tissue.
• Resulting from inflammatory reactions.
4 marks for methods of preventing and reducing muscle soreness:
• Warm-up and the use of active recovery between bouts of work.
• Cool-down keep blood capillaries dilate.
• To flush out lactic acid.
• And to continue adequate supplies of oxygen to working muscles.
• Use of ice baths immediately following the session, will reduce muscle and joint inflammation.
• Use of full body compression clothing during the weight training session, aids venous return and reduces DOMS.
• Have a sports massage, following cool-down to relieve muscle soreness and pain and reduce tissue oedema.
• Gradually increase the training programme by increasing the intensity and repetitions and sessions over a period of weeks.
• Enabling long-term muscle adaptation without severe muscle soreness.
• Use of training principles - moderation, variance and rest in programme planning.
• Exercise different muscle groups on different days to enable muscle groups to recover.
• For example, arm and shoulder strength exercises on day one and leg and trunk strength exercises on day two.
10) Recommend a method of optimising glycogen repletion following hard physical activity.3 marks
Answer
• Active cool-down or Cori cycle or conversion of lactic acid into glycogen.
• High CHO diet as soon as possible after activity to enhance glycogen refuelling.
• Scheduled rest days when little glycogen is used.
• Variations in training loads i.e. hard, medium to easy so that glycogen stores are not heavily taxed all the time.
11) Following an intense training session, explain how the following ergogenic aids assist with the recovery process: having an ice
bath, having a massage, wearing full body compression clothing during a cool-down, and ingesting a hypertonic sports drink.
8 marks
Answer
2 marks for having an ice bath:
• Will reduce joint and muscle inflammation (hot spots).
• Produced by torn blood vessels and microtears in muscle tissue.
2 marks for having a massage:
• Stretches soft tissue thereby relieving muscle tension and increasing muscle relaxation.
• Reduce swelling caused by torn blood vessels.
• Increases the movement of interstitial fluids that carry away the waste products of fatigue.
• And stimulate a supply of nutrients, such as O2 and glucose, which speed up the recovery process.
• Relieves pain and anxiety – it is often a pleasant experience.
• Helps prevent injury by dealing with niggles.
2 marks for wearing full body compression clothing during a cool-down:
• Aids venous return
• Reduces DOMS.
• Hence enhanced recovery.
2 marks for ingesting a hypertonic sports drink:
• Aids rehydration.
• Aids refuelling of depleted glycogen stores.
• Replaces electrolytes (minerals - such as sodium) lost through sweating.
• The inclusion of sodium facilitates water storage.
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