This document discusses aerobic capacity and factors that affect it. Aerobic capacity is the ability of the body to take in, transport, and use oxygen during prolonged submaximal exercise. It depends on the efficiency of the pulmonary, cardiovascular, and muscular systems. VO2 max is the maximum rate of oxygen consumption during maximal exercise and is a measure of aerobic endurance. Aerobic training can improve VO2 max by 10-20% through adaptations to these body systems that enhance oxygen intake, transport, and utilization.

1. Aerobic Capacity
A2

2. AEROBIC CAPACITY
AEROBIC CAPACITY
• the ability to take in, transport and use oxygen to
sustain prolonged periods of aerobic/sub-maximal
work.
• Aerobic capacity is dependent upon the efficiency of
the following systems:
• Pulmonary ventilation and external respiration
• Internal transport via the heart, blood and blood
vessels
• Muscle cells to use oxygen for energy production

3. VO2 Max
• This is closely linked to aerobic capacity but there is a difference:
• VO2 max is defined as the highest rate of oxygen consumption
attainable during maximal/exhaustive work.
• VO2 is thought to be the best indicator of aerobic endurance.
VO2max
• mean values are :
• males (20 yo) = 40 ml kg-1 min-1
• (for average male body mass 87.5 kg)
• females (20 yo) = 35 ml kg-1 min-1
• (for mean female body mass 66 kg)
• endurance athletes = 75 ml kg-1 min-1
• (for mean body mass 66 kg)

4. VO2 example

5. Factors affecting VO2 Max
• Individual Physiological Make-up
• Efficiency of:
• Respiratory system to consume O2
• Heart to transport O2
• Vascular system to transport O2
• Muscle cells to use O2
• An increase in VO2 max would be linked to all of these
systems. The higher VO2 max the greater potential to
work at that level, just below the anaerobic
threshold, increasing work intensity and delaying
fatigue.

6. Factors affecting VO2 Max
• Heredity/Genetics
• This can account for variation in VO2 max:
• If an athlete has a greater percentage of type I or
type IIa fibres. This may affect how much they
can improve by.
• However, heredity only indicates an individuals
potential to have a high VO2 max. It is ultimately
the aerobic training they undertake that helps
them achieve their potential.

7. Factors affecting VO2 Max
• Training
• A programme of aerobic training will increase
VO2 max. A maximum level of aerobic
conditioning can be reached within
approximately 8-19 months of heavy
endurance-based training.
• Aerobic training can cause VO2max to be
improved by 10 - 20%

8. Factors affecting VO2 Max
• Age
• The limitation in oxygen transport to the
muscles and a decreased a-VO diff are the
main causes of a reduced VO2 max. It is
thought that VO2max reduces at about 10%
per decade (1 per cent per year) during ageing
- for sedentary people.
• VO2max reduces less for active sportspeople
as they age

9. Age and VO2 max
• The decrease is thought to have 2 main causes:
• Cardiovacular – maximum HR, cardiac output
(Q), stroke volume (SV) and blood circulation to
muscle tissues decrease due to a decreased left
ventricular contractility/elasticity.
• Respiration – lung volumes, for example max VE
(minute ventilation), decrease linearly after
maturation due to a decrease in elasticity of lung
tissues and thoracic cavity walls.

11. Factors affecting VO2 Max
• Gender
• VO2 max values for woman are generally 20-25% lower than males.
Woman are disadvantaged by having a greater body fat
percentage, since this decreasesVO2 max when measured per kilogram
of body weight.
• Women’s smaller body size also means:
• A smaller lung volume – decreases external respiration and oxygen
intake
• A smaller heart – increases resting HR, lowering SV and Q at maximal
rates of work
• Lower blood/haemoglobin levels decrease oxygen transport and blood
volume.
• women have greater reductions in VO2max from late teens onwards
probably because of the tradition of less physical activity for women

12. AEROBIC CAPACITY
IMPORTANCE OF AEROBIC CAPACITY TO ENDURANCE PERFORMERS
• useful as an indicator showing athletes’ maximal physiological capacity
• repeated tests would show the effects of endurance training on
VO2max
EXAMPLE OF SPORTING ACTIVITIES
• swimming (>200m)
• running (>800m)
• cross country skiing
• games lasting longer than a few minutes
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13. AEROBIC CAPACITY
AEROBIC FITNESS TESTS
There are many tests that vary in validity and reliability. Two tests that you are
required to know are both ‘indirect’ which estimate and predict a VO2 max
value based on test results.
• PWC 170 test
– A submaximal test on a cycle ergometer. The performer cycles at 3
progressive low-moderate work intensities (100-115bpm, 115-130bpm and
130-145bpm) and their HR values are recorded. As HR increases linearly with
work load a line can be drawn through these 3 points to predict level of work
at a HR of 170 bpm
• Multistage shuttle run test (bleep test)
– the subject runs a progressively quicker shuttle run to exhaustion
– each level and shuttle in the progression is numbered
– the level reached by the subject is correlated to the VO2max
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14. Aerobic Training
• To enable you to plan a training programme you will be required
to know continuous, fartlek, interval training and repetition
running. It is important to measure the intensity. Training zones
and target heart rates are often used as they are more practical.
• A simple formula to calculate the appropriate HR
percentage, often termed the critical threshold and based on
Karvonen’s principle (220-age = max HR) is below:
• Critical Threshold = resting HR + %(max HR-resting HR)
• EG: for 60% HR for a 17 year old with a resting HR of 72:
• CT = 72 + (0.60 x 131) 79 = 151 (203 – 72 = 131) = (max HR –
resting HR)
• Individuals working at the top end of the training threshold
would get greater adaptations.

15. MONITORING EXERCISE INTENSITY
TARGET HEART RATE AEROBIC TRAINING ZONE
• a specific heart rate (HR) to be achieved • this is shown on graph
and maintained during exercise
• which shows a range of HR values at
• if aerobic adaptations are to which aerobic training should occur
occur, training must take place at a HR
above the aerobic threshold • this will enable adaptations to occur
• this theory is based on the fact that VO2 which improve VO2max
is proportional to HR
HR ESTIMATION
• HR will depend on fitness of athlete
• maximum HR
HRmax = 220 - age
• aerobic threshold (Karvonen)
HR = HRrest + 0.6(HRmax - HRrest)
• example :
– age = 20, HRrest = 70 bpm
– HRmax = 220 - 20 = 200 bpm
– aerobic threshold HR
= 70 + 0.6(200 - 70)
= 70 + 0.6 x 130 = 70 + 78
.15 = 148 bpm 1/12/2012

16. AEROBIC CAPACITY
ADAPTATIONS PRODUCED BY AEROBIC TRAINING
• cardiovascular system becomes more efficient
• heart becomes bigger and stronger and pumps more blood per pulse
• more haemoglobin is available in blood for oxygen transport
• capillary system in muscle bed is utilised better and developed
• pulmonary systems become more efficient
• musculature of torso becomes stronger and more efficient
• lung volumes increase slightly, greater volumes of air can be breathed per
breath
• efficiency of alveoli improves, and more alveoli are utilised
• more myoglobin and mitochondria are created in muscle cells
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17. Aerobic Training Methods
• This involves whole body activities like
running, cycling, rowing and swimming, and is aimed at
overloading the cardio-vascular/respiratory systems to
increase aerobic capacity/VO2 max.
• Overload is achieved by applying the principle of FITT.
• F – Frequency – a minimum of 3-5 times per week for a
minimum of 12 weeks
• I – Intensity – measured using HR% within a critical
threshold/training zone
• T – Time/duration – a minimum of 3-5 minutes to 40+
minutes
• T – Type – overloading the aerobic energy systems

18. TYPES OF TRAINING USED TO DEVELOP AEROBIC CAPACITY
CONTINUOUS TRAINING FARTLEK TRAINING
• exercise regimes lasting longer than 3 • fartlek means ‘speed play’
minutes
• pace is varied from sprinting to
• involving low forces jogging
• where breathing is comfortable and
• this is a combined form of continuous
the activity is aerobic
and interval training
• examples :
– jogging, swimming, step aerobics
• normally performed in the
countryside
INTERVAL TRAINING (repetition • over 45 minutes or longer
running) • can include all round body exercises
• characterised by sets, repetitions and between running bouts
rest relief • helps develop VO2max and the
• example : recovery process
– swimming :
• 2 sets of 10 at 50m at 70%
effort
• with 30 seconds rest relief
between repetitions, and 3
minutes rest between sets
.18 – circuit training, weight training 1/12/2012

19. FOOD FUEL USAGE FOR AEROBIC
FOOD FUEL USAGE ACTIVITY
• this depends on :
– EXERCISE INTENSITY
– EXERCISE DURATION
AT REST
• ATP utilisation is slow
• a mixture of fats and carbohydrates
is used to resynthesise ATP
FOR LOW INTENSITY LONG DURATION
AEROBIC ACTIVITY
• usage of a variety of fuels
• but mainly the oxidation of a
mixture of CHO and fats
• the longer the exercise the bigger
the proportion of ATP resynthesis
provided by fats
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20. FOOD FUEL USAGE FOR AEROBIC ACTIVITY
SOURCES OF FUELS
• main source of CHO for muscular energy during exercise is glucose
• derived from stored muscle and liver glycogen
• lack of CHO fuel is the limiting factor for aerobic endurance performance
• main source of fat for muscular energy during exercise is free fatty acids
(FFA)
• derived from triglycerides stored as adipose tissue under the skin and in
muscle tissue
• triglycerides break
down into FFA for
entry into the
aerobic energy
system
• proteins become a
significant source of
energy only in
extreme conditions
• when CHO and fats
are depleted
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21. FOOD FUEL UTILISATION DURING AEROBIC EXERCISE
GLYCOGEN SPARING AS A LONG-TERM
ADAPTATION TO AEROBIC TRAINING
• for the person who has undertaken
sustained aerobic training
• an adaptation is produced where fats are
used earlier on in exercise
• thus conserving glycogen stores
(respiratory exchange ratio (RER) indicates
greater use of fats)
• the graph shows a higher proportion of
fats utilised by the trained person
• thereby releasing CHO for higher intensity
work
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22. AEROBIC CAPACITY
ADAPTATIONS PRODUCED BY AEROBIC TRAINING
CARDIAC RESPONSE
• blood plasma volume increases with training
• therefore increased blood plasma volume enters left ventricle
• increasing the stretch of the ventricular walls by the Frank-Starling mechanism
• cardiac hypertrophy – heart becomes bigger and stronger (mainly left ventricle)
• increased ventricular muscle mass and stronger elastic recoil of the myocardium
• causes a more forceful contraction during ventricular systole
• therefore stroke volume increases and HR decreases (bradycardia)
• and hence providing more oxygen per pulse
• the net effect is up to 20% bigger stroke volume and greater oxygen
delivery to muscles
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23. AEROBIC CAPACITY
ADAPTATIONS PRODUCED BY AEROBIC TRAINING
• cardiovascular system becomes more efficient
VASCULAR RESPONSE
• more haemoglobin is created and is available in blood for oxygen transport
• capillary system in muscle bed is utilised better and developed
• there is increased capillarisation of trained muscle
• and improved dilation of existing capillaries due to increased blood volume
• increased elasticity and thickness of smooth muscle of arterial walls makes
walls tougher and therefore less likely to stretch under pressure
• hence a more effective blood distribution
• this maintains blood pressure forcing blood through capillary network
• during ageing arteries lose muscle and hence stretch more under pressure
• hence greater BP required to force blood through capillary system
• heart has to work harder
BLOOD VESSELS IN THE HEART
• blood flow to heart decreases because heart muscle is more efficient
• hence decrease in resting HR
• and increase in diastolic HR during maximal workloads
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24. AEROBIC CAPACITY
ADAPTATIONS PRODUCED BY AEROBIC TRAINING
• pulmonary systems become more efficient
RESPIRATORY RESPONSE
• musculature of torso becomes stronger and more efficient
• lung volumes increase slightly, greater volumes of air can be breathed per
breath
• increase in VC at the expense of RV
• hence decrease in breathing rate (f) at submaximal workloads
• and increase in breathing rate (f) at maximal workloads
• hence large increase in volume of air breathed per minute (VE)
• increase in pulmonary blood flow and plasma volume
• efficiency of alveoli improves, and more alveoli are utilised
• hence increased gaseous exchange and VO2max
RECOVERY
• improved oxygen recovery
• with better muscle capillarisation and efficient cool-down, lactic acid removal is
improved
• hence reduction in DOMS
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25. CELLULAR ADAPTATION PRODUCED
BY AEROBIC TRAINING AFTER SEVERAL WEEKS OF
AEROBIC TRAINING
BEFORE TRAINING
glycogen glycogen
fats fats
oxygen uptake oxygen uptake
= SLOW TWITCH MUSCLE FIBRE (type I)
= FAST TWITCH MUSCLE FIBRE (type II) (do not increase in size)
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26. AEROBIC CAPACITY
ADAPTATIONS PRODUCED BY AEROBIC TRAINING
MUSCLE CELL RESPONSE
• more myoglobin is created in muscle cells
• more and bigger mitochondria in muscle cells
• increased oxidative enzymes glycogen
phosphorylase, phosphofructokinase, lipoprotein lipase
• hence increased activity of Kreb’s cycle and electron transport chain
• and increase in stores and utilisation of fat
• increase in stores of glycogen in muscle
• which enables more fuel to be available for aerobic work
• conversion of type IIb to type IIa fibres
NEURAL RESPONSE
• better recruitment of slow twitch fibre motor units making muscle usage
more efficient
.26 1/12/2012