Transcript Chapter 7 - Fitness Components

KEY KNOWLEDGE
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Health-related fitness components
including aerobic capacity,
anaerobic capacity, muscular
strength and endurance, flexibility,
body composition
Skill-related fitness components
including muscular power, speed,
agility, coordination, balance and
reaction time
Factors that affect each component.
KEY SKILLS
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Using relevant technology,
conduct an activity analysis to
collect and interpret primary
data, and so ascertain the
important fitness components
and energy systems used in
sports and physical activities.
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© Cengage Learning Australia 2011
Aerobic capacity
= The ability of the cardiovascular and
respiratory systems to take up and supply
oxygen to the muscles to sustain exercise.
Factors affecting aerobic capacity
VO2 max – The higher this is, the more oxygen can be taken up, transported and
utilised per kg of body weight and the greater the ability to supply ATP aerobically.
When working maximally it is possible to attain 90% of one’s VO2 max within 1 minute.
Lactate inflection point (LIP) – The later this occurs during activity (increased via
aerobic training), the less likelihood hydrogen ions (H+) will accumulate and affect
aerobic energy production. Aerobic glycolysis is preferred exercise state to supply ATP
aerobically.
Gender – males have greater aerobic power than females because, amongst other
factors, they have larger hearts, lungs and blood volumes. See norms below.
Age – VO2 max peaks around 25–28 years of age and then declines by 1% per year
Heredity – aerobic power/ VO2 max has a heredity estimate of 90–95%
Training – Athletes able to increase their stroke volume (SV), cardiac output (Q),
blood volume, capillary density, lactate inflection point (LIP), arterio-venous oxygen
difference (a-vO2 diff), and slow-twitch muscle fibre characteristics will greatly
improve their aerobic capacity.
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Anaerobic capacity = The ability of the body to produce
energy without using oxygen and hence the efficiency/‘power’ of the two
anaerobic energy systems ~ ATP–PC & anaerobic glycolysis systems.
Factors affecting anaerobic capacity
Age – Anaerobic power tends to peak around 30 years of age and then decline by
1% per year. It declines because the body becomes less able to synthesise protein
(delayed by training), decreases in cross sectional area of muscle fibres and
resulting decreases in fuel stores (ATP & PC & glycogen) and anaerobic enzymes.
Gender – Males have greater muscle mass than females so will also have greater
stores of ‘anaerobic fuels’ (ATP & PC) and glycolytic enzymes that can break down
glycogen quickly without oxygen.
Lactic acid and metabolite tolerance – anaerobic training calling upon the LA
system will greatly improve the muscle’s abilities to tolerate build up of LA, H+, ADP
and inorganic phosphates.
Fibre type – Fast-twitch fibres can generate anaerobic power quicker than slowtwitch fibres because they have greater anaerobic stores of fuels.
Fibre recruitment – Anaerobic power relies upon fast-twitch fibres being activated
quickly and hence many ‘intense’ impulses are sent to relevant muscle groups
requiring quick activation.
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Muscular strength = The force or tension a muscle (group) can exert
against a resistance in one maximal contraction. The maximum amount of force produced
in one contraction is also known as 1RM (one repetition maximum). The contraction is
often applied over a couple of seconds.
Factors affecting muscle strength
Age – muscular strength will tend to peak between 25–30 years of age and then decline by 1% a
year.
Gender – males have greater muscle mass than females so in absolute terms will be ‘stronger’
by about 30%. The same male and female muscle types are able to produce the same strength.
Speed of contraction – greatest strength can be generated with isometric contractions. As
speed of contraction increases for isotonic and isokinetic contractions, the strength produced
decreases.
Fibre type – fast-twitch fibres can generate more strength than slow-twitch fibres because they
have greater diameters and contractile proteins (the part of fibres responsible for generating
tension).
Fibre arrangement/shape – multipennate muscles will be stronger than bi-pennate or
unipennate muscles due to greater attachment points. Quadriceps (multipennate) are approx.
Three times stronger than hamstrings (unipennate and fusiform).
Fibre recruitment – efforts requiring minimal strength such as picking up a hockey stick see a
small number of fibres being recruited by nerve impulses. The same hockey stick used to
generate greater strength in a push from a penalty corner will be activated by a greater number of
fibres being recruited.
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Local muscular endurance = The ability of a muscle, or
commonly group of muscles, to continue sustained contractions in the face of fatigue.
Factors affecting local muscle endurance
Blood flow – if blood vessels become occluded/blocked as a result of muscles ‘squeezing’
them, fatigue will result. This is commonly related to accumulation of inorganic phosphates
(anaerobic breakdown of CP and ATP) and H+ accumulation.
Training – aerobic training will increase blood/oxygen supply to muscle tissue and so increase
aerobic ATP production and removal of metabolic by-products. Greater amounts of oxygen will
also be extracted by working muscles and decrease amount of anaerobic ATP reliance.
Lactic acid and metabolite tolerance – anaerobic training calling upon the LA system will
greatly improve the muscle’s abilities to tolerate build up of H+, ADP and inorganic
phosphates.
Muscular strength – muscles displaying increased levels of muscular strength will show
greater LME. This partly occurs because of lower likelihood of occluded blood supply and
increased abilities to keep using the LA system when called upon increasingly as the activity
progresses. Because of this, males and females displaying similar/same strength will have
very little/no differences in LME.
Age – because LME is closely related to muscular strength, it will also tend to peak at 25–30
years of age and then decline by 1% per year.
Muscle temperature – elevated temperatures will decrease LME because muscles will
increasingly be performing anaerobically and less oxygen is directed to working muscles.
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Flexibility = The ability of a joint to move through its full range of
motion.
Factors affecting flexibility
Joint structure – the more stable a joint is via its capsule and connective tissue the
stronger it is, but the less flexible it becomes. Flexibility must be expressed with reference
to a joint or sequence of joints.
Age – flexibility tends to be greatest at various body joints between the ages of 8–10.
Gender – females tend to be more flexible than males because, amongst other reasons,
they possess greater levels of oestrogen.
Resistance – (muscle, bones, tendons and ligaments = connective tissues and fat). The
greater the resistance provided by these structures, the lower the resultant flexibility.
Somatotype – excessive fat (endomorphy) and muscle tissue (mesomorphy) will both
contribute to reduced levels of flexibility.
Temperature – warming-up will decrease joint viscosity and contribute to increased
flexibility.
Training – dynamic flexibility should be incorporated into all training sessions (warm up
and warm down) to avoid reduction in joint flexibility and decreases in biomechanical
movement efficiency.
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Body composition = The ratio of fat-free mass to fat
mass and essentially a person’s body ‘shape’ or somatotype.
Factors affecting body composition
Age – after 40 years of age, people’s metabolism tends to slow down and in
women hormonal imbalances can cause them to increase % body fat.
Gender – average male body fat is approx 15%; average female body fat =
25%.
Fibre type – people with a higher percentage of fast twitch fibres have lower %
body fat.
Genetics – body types tend to be 90% genetically inherited.
Energy balance – people with a positive energy balance will have higher %
body fat.
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Muscular power = The ability to exert a maximal contraction
in one explosive effort.
Factors affecting muscle power
Age – muscular power will tend to peak around 25 years of age and then decline by
1% per year.
Gender – males have greater muscle mass than females so will also have greater
muscular power.
Speed of contraction – greatest power/force generated when both speed of
contraction and force of contraction are around 35% of each maximum. Moderate
speed and strength will generate maximal muscular power.
Fibre type – fast-twitch fibres can generate muscular power quicker than slow-twitch
fibres.
Fibre recruitment – muscular power relies upon fast-twitch fibres being activated
quickly and hence many ‘intense’ impulses are sent to relevant muscle groups
requiring explosive efforts.
Muscle length – muscles are able to apply greatest power when stretched just past
their resisting length coinciding with maximum actin–myosin overlap and cross bridge
formation. So movements involving eccentric contractions generate greatest muscular
power.
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Speed = The ability to move the whole body, or body parts, from one place to another in
the shortest possible time. When speed remains maximal and constant, this is known as speed
endurance, and must be linked with LME as speed is maintained despite accumulating metabolic
by-products
Factors affecting speed
Fibre type – fast-twitch fibres can generate greater speeds than slow-twitch fibres.
Fibre recruitment –speed relies upon fast-twitch fibres being activated quickly and hence many
‘intense’ impulses are sent to relevant muscle groups requiring explosive efforts.
Fibre arrangement/shape – fusiform muscles with low attachment points contribute to speed more
than pennate muscles which are stronger.
Reaction time – faster reaction times contribute to quicker movements.
Muscular strength – the greater one’s muscular strength, the greater the speed.
Range of motion at joints – the greater the range of motion due to increased
viscosity/temperatures and low restriction from fat, muscle bulk, scar tissue, the quicker movements
can occur.
Lactic acid and metabolite tolerance – anaerobic training calling upon the LA system will greatly
improve the muscles’ abilities to tolerate build up of H+, ADP and inorganic phosphates and hence
contribute greatly to speed endurance.
Efficiency of movement – correct techniques ensuring maximum acceleration and summation of
force contribute to greatest speed.
Heredity – bone/lever length (longer bones are capable of generating greater speed than shorter
ones) and ligament/tendon attachment sites (longer and less restrictive attachments) all contribute to
greater speed development. It should be noted that fast-twitch:slow-twitch ratios are also inherited.
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Agility = the ability to change body position or direction quickly and
accurately whilst maintaining balance.
Factors affecting agility
Centre of gravity (cog) – athletes with a lower cog tend to be more agile due to
greater abilities to balance.
Speed – males are faster than females and hence will have greater agility than
females.
Reaction time – faster reaction times contribute to quicker movements and
greater agility.
Range of motion at joints – the greater the range of motion due to increased
viscosity/ temperatures and low restriction from fat, muscle bulk, scar tissue, the
more agile performers will be.
Fibre type – fast-twitch fibres can generate greater speeds and are called upon
before slow-twitch fibres as part of preferential recruitment during agile activities.
Flexibility – females have greater amounts of flexibility at various joints than
males which accounts for smaller differences between the genders compared to
other fitness components.
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Coordination = The ability to use the body’s senses
to execute motor skills smoothly and accurately.
Factors affecting coordination
Sequencing of movements – the more parts or sequences to a
movement, the higher the level of co-ordination required
Stage of learning – autonomous performers are more
coordinated than associative or cognitive performers.
Practice/learning – there is a direct relationship between
amount of learning and coordination.
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Balance = The ability to maintain equilibrium whilst stationary
(static) or moving (dynamic)
Factors affecting balance
Base of support – the greater the base of support, the greater the
equilibrium.
Centre of gravity – by lowering one’s centre of gravity, balance is
increased.
Core stability – greater core stability leads to improved balance.
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Reaction time = The time between a signal being detected
and the first movement/ response to this signal.
Factors affecting reaction time
Optimal arousal and concentration – both these factors will contribute
to quick and appropriate reactions.
Number of responses – reaction time is quickest when there is only one
possible response. If there are several possible responses, performers
must decide which one they are going to use and reaction time is slowed.
‘Noise’ – distractions add to reaction time and slow down responses.
© Cengage Learning Australia 2011