Chapter 2 Cardiorespiratory Fitness

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Chapter 2 Cardiorespiratory Fitness
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CV Fitness Maximum Oxygen Consumption

• VO2max CO avO2diff
• VO2 volume oxygen consumed per minute, it is a
  function of the amount of oxygen delivered (CO)
  and the amount of oxygen extracted from the blood
  (avO2diff). Maximum oxygen consumption is a
  measure of CV fitness.
• CO cardiac output, the amount of blood pumped
  by the heart per minute, it is a function of how
  fast the heart beats (HR, heart rate) and how
  much blood is pumped out with each beat (SV,
  stroke volume). CO HR SV

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CV Fitness Maximum Oxygen Consumption

• The equation is now VO2max HR SV avO2diff
• avO2diff arterial, venous oxygen difference,
  the difference between the arterial oxygen
  content and the venous oxygen content of the
  blood, i.e. the amount of oxygen extracted.

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Changes with Training

• Endurance exercise training results in large
  increases in maximal oxygen consumption (VO2max),
  i.e. cardiovascular fitness. As much as 30-40
  from 3.5 LO2/min to 5LO2/min.
• HOW? ?VO2max ?HR ?SV ?avO2diff

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Changes with Training

• avO2diff the body is already very good at
  extracting oxygen from the blood, however small
  changes do occur as a result of increased
  oxidative capacity and increased capillarization
  of trained muscles accounting for a change from
  about 143 mlO2/min to 156 ml O2/min, a 9
  increase.
• CO the delivery of oxygen changes dramatically
  with training as the heart becomes a bigger more
  efficient pump. From 25 L/min to 36 L/min, a 44
  increase accounting for most of the change in
  VO2max

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Changes with training Cardiac Output

• Recall that CO is made up of HR and SV
• HR maximal HR can be predicted by the following
  equation HRmax 220 age (little difference
  with training or even a decrease)
• SV stroke volume, the amount of blood pumped
  out with each beat can increase with training
  from 112 ml/beat to 189 ml/beat, 68. Therefore,
  SV accounts for the change in CO and ultimately
  the majority of the change in VO2max that occurs
  with training.

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Changes in SV

• In order for the heart to pump more blood per
  beat (SV), more blood must return to the heart
  and the heart must have a greater
  capacity/volume, particularly the volume of the
  LV.
• Endurance exercise training results in volume
  overload, i.e. as the exercising muscles
  rythmically squeeze the veins more blood is
  pumped back to the heart. More blood returning
  to the heart stretches the heart and over time
  the physical adaptation to increased blood return
  is an increase in size of the heart chambers
  allowing for greater volume.

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Summary and test

• So, with endurance training cardiovascular
  fitness (VO2max) increases and a majority of this
  increase is accounted for by increased CO or more
  specifically increased SV caused by a physical
  change in the size of the heart chambers (with
  every beat the heart pumps out more blood in a
  trained person versus an untrained person).

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Test

• What about differences at rest?
• VO2rest 300 ml/min, trained or untrained it
  takes about the same amount of energy to veg out.
• So what happens to the equation?
• VO2rest ?HR ?SV ?avO2diff
• (no change)

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Test

• avO2diff for now consider that there is little
  difference in the ability to extract oxygen
  between trained and untrained.
• VO2rest ?HR ?SV avO2diff
• (no change) (no change)
• Is stroke volume higher or lower in the trained
  individual at rest compared to the untrained
  individual?

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Test

• Answer Higher
• There is a physical change in the size of the
  heart chambers so the heart pumps out more blood
  with every beat.
• VO2rest ?HR ?SV avO2diff
• (no change) (no change)
• So, are heart rates (HR) higher or lower at rest
  in a trained individual compared to an untrained
  individual?

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Test

• Answer Lower
• VO2rest ?HR ?SV avO2diff
• (no change) (no change)
• A trained individual can maintain the same VO2
  and CO as an untrained individual at a lower HR
  because SV is higher and the heart is a more
  efficient pump!

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Extraneous facts

• How much lower are HR in trained individuals?
• Normal all ages 72 bpm
• Normal young and healthy 60 bpm
• World class endurance athlete (Lance Armstrong)
  31 bpm!
• Blue whale 3 bpm

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How to increase CV Fitness

• 6 Principles of Training
• Frequency most or all days of the week
• Intensity 60-90 of HRmax
• Time/duration 30 min or 3 x 10 min
• Progression
• Overload
• Specificity

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Intensity

• Exercise intensity is usually determined by
  measuring HR. HR and VO2 are linearly correlated
  and therefore HR can be used a measure of the
  stress on the CV system.
• In order to achieve improvements in CV fitness,
  the CV must be stressed beyond a certain
  threshold (Overload). However, if the intensity
  is too high the activity will not be maintained
  long enough to cause beneficial adaptations.
  Therefore, exercise intensity for improvements
  should elicit 60-90 of an individuals HRmax.
  This is called the Target Heart Rate.

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Target HR

• HRmax can be estimated by the following equation
• HRmax 220 age
• Target Heart Rate is then calculate as follows
• 60 HRmax HRmax 0.6
• 90 HRmax HRmax 0.9

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Target Heart Rate example

• Target heart rate for a 20 year old would be
• HRmax 220 20 200 bpm
• (age)
• 60 HRmax 200 0.6 120 bpm
• 90 HRmax 200 0.9 180 bpm
• (HRmax)

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Type of Exercise Specificity

• Increased CV fitness is due in large part to
  volume overload training in which increased blood
  return results in increased heart size,
  particulary the volume of the heart chambers.
• The more muscle mass involved in dynamic,
  rhythmic exercise results in increased blood
  return to the heart. So, exercise training
  involving large muscle mass, such as the legs, is
  the best for improving CV fitness.
• EX running, walking, cycling, cross country
  skiing, swimming

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Warm-up/Cool-down

• 5 min of light activity
• Stretching

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Environmental Factors

• Exercise in the Heat
• Exercise in the Cold