Nelson Physical Education Units 3 & 4
Checkpoints solutions
Chapter 6
Nelson Physical Education
VCE Units 3 & 4
Checkpoints solutions
Chapter 6: Muscular fatigue
mechanisms
Checkpoints p. 134
1 Fatigue shows in working muscles as a loss of force and power. As fatigue sets in
the working muscle is no longer able to respond to stimulation and maintain the
same level of contractile activity. The muscle gradually fails to achieve the
tension required to continue a task.
2 The onset and rate of development of fatigue is dependent on the:
 type of activity being undertaken  intermittent or continuous
 muscle fibre type being used  fast- or slow-twitch fibres (slow-twitch fibre
types are more resistant to fatigue)
 types of muscular contractions occurring  isotonic, isometric or isokinetic
 intensity and duration of the activity undertaken (the onset of fatigue is more
rapid with high-intensity work)
 level of fitness of the performer.
3 Localised, general and long-term fatigue are similar in that they can all be
detected physiologically. The differences between them are that local fatigue is
detected in a specific area of the body, general fatigue is felt all over the body and
long-term fatigue can involve both physiological and psychological signs and
symptoms.
4 The primary factors involved in fatigue are depletion of fuels (specifically
glycogen and creatine phosphate), the depletion of high-energy phosphate
compounds, altered levels of metabolic by-products (such as ADP and inorganic
phosphate), reduced rates of energy liberation, elevated body temperatures,
dehydration and changes in the distribution of blood flow.
Checkpoints p. 137
1 the energy stores most commonly exhausted in the early stages of exercise are
phosphocreatine and glycogen.
2 Depletion of energy stores dramatically affects the production of ATP, reducing
the rate of energy production.
3 The products formed in the muslce sell when a constant supply of ATP is required
for muscles ocntraction are ADP, lactic acid and inorganic phosphate Pi.
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Nelson Physical Education Units 3 & 4
Checkpoints solutions
Chapter 6
4 The metabolic consequence of supplying ATP anaerobically may be that the
pyruvic acid that is formed as a result of this process is convereted to lactic acid.
5 There is a correlation between muscle fatigue and an increase in lactic acid. It is
thought that the accumulation of lactic acid raises the pH level of the muscle and
may inhibit key enzymes in the energy-producing pathway.
Checkpoints p. 138
1 Working muscles need a greater volume of blood during exercise because during
exercise, the demand for oxygen and nutrients in the muscle cells increases and
there is an increased need to remove wastes from the site of the muscle. A greater
volume of blood aids this process.
2 During exercise, the active muscles and skin receive the most cardiac output. All
other organs receive less.
Checkpoints p. 141
1 During exercise, the body uses the following methods to regulate its temparature:
 Sweating (loss of body fluid), which generates a cooling effect as it evaporates
 Vasodilation of blood vessels to increase blood flow to the periphery of the body
and facilitate the transfer of heat through the skin
2 The amount of sweat produced increases with exercise intensity and is further
increased by hot and humid conditions and wearing heavy clothing while
exercising.
3 Dehydration occurs when fluid loss is greater than fluid intake.
4 Factors contributing to an athlete becoming dehydrated include limited
opportunity to drink, or limited availability of drinks during the activity; an athlete
having poor drinking strategies or poor tolerance of drinks during competition;
and an athlete’s inability to match excessive sweat rates. Additionally,varying
rates of sweat, work, fluid intake and individual physiological characteristics all
contribute to the level of dehydration that may be experienced. Sweat rates vary
widely between individuals.
5 Dehaydration effects performance in a number of ways:
 Early fatigue and impaired physical and mental performance
 Athlete is more susceptible to cramp, heat stress and heat stroke
 Loss of performance and increased risk of injury
 Increase in perceived effort and possible reduction in performance
 Impaired reaction time, judgment, concentration, cognitive and decision making
skills
6 Some of the symptoms of dehydration include mild to severe thirst, rapid drop in
weight, dry lips and tongue, a decrease in the amount of urine passed and urine
may appear darker than normal, faster breathing and heart rate than normal,
weakness or light headedness, confusion, nausea and headache.
7 To monitor hydration levels, an athlete could weigh themself before and after
performance to gauge fluid loss, measure the amount of fluid consumed, note the
color of urine, drink before thirst sets in.
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Nelson Physical Education Units 3 & 4
Checkpoints solutions
Chapter 6
8 To ensure that optimum levels of hydration are achieved during competition, an
athlete should:
 not wait until he/she is thirsty before they drink, as thirst is a poor indicator of
hydration levels
 drink cool water, as it is absorbed more rapidly than warm water
 use a sports drink if exercising for longer than one hour
 adopt a fluid replacement routine
 avoid starting exercise dehydrated
 drink plenty of fluid for several hours prior to exercising
 drink at least 500 mL of water half to one hour prior to exercise
 drink at least 200 mL of water every 15 minutes during exercise
 drink at least 500 mL to 1 litre of water after exercise and continue to drink until
fluid losses are replaced
9 Factors responsible for fatigue include changes to internal conditions of the
muscles, depletion of fuels, production of metabolic by-products and dehydration.
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