Adaptations to Aerobic training

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Adaptations to Aerobic training
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Terms

• acute vs. chronic
• constant load vs. incremental load
• trained vs. untrained
• maximal vs. submaximal

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Introduction

• At rest supply demand
• Exercise demand increases
• To the muscles
• To the heart
• To the skin
• Maintain flow to the brain
• Can the heart supply enough O2 to meet the
  demand?
• What causes fatigue during maximal aerobic
  exercise?

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Heart Rate

• Most important factor for increasing cardiac
  output.
• How does it increase?
• Decrease parasympathetic stimulation
• Increase sympathetic stimulation
• Steady state exercise
• Cardiovascular drift
• Decreased blood volume
• filtration from the blood
• sweating

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Heart Rate

• Increases with intensity and levels off at VO2max
• 220 age ( 12)

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Stroke Volume

• Increases until about 25-50 of maximum
• After that it may plateau or continue to increase
• Decrease at VO2max? If so, why?
• decrease filling time
• decrease in venous return

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Result (SV HR)

• Increase in cardiac output
• Increases with intensity

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Blood Pressure

• Blood pressure Q x TPR
• Q?
• SBP?
• How much?
• 250 maximal aerobic exercise
• 450 with 1 RM testing
• High blood pressure, RPP, and ischemia
• What if blood pressure decreased during exercise?

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Blood Pressure
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a-v O2 difference

• How?
• No change in PaO2 in the blood
• Decrease in PaO2 in the muscle
• Greater pressure difference between the blood and
  the muscles
• Therefore, more O2 diffuses into the muscles

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Result

• Increase in cardiac output
• With help from HR and SV
• Increase in (a-v)O2
• More O2 is supplied and extracted
• Therefore, more O2 can be used by the muscle
  fibers (mito)

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Oxygen Consumption

• VO2 increases with intensity
• VO2 rate of blood flow times the O2 extracted
  from a given amount of blood
• VO2 cardiac output x a-vO2 difference
• VO2 can increase by
• A greater blood flow
• Taking more oxygen out of every 100 ml of blood

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Limitations of the CV during acute exercise

• Coronary blood flow
• Occurs during diastole
• Range from 260 ml/min to 900 ml/min
• Warm-up helps achieve adequate increase
• Cerebral blood flow
• Up to 75 ml/min or an increase of 25 during
  exercise
• Muscle blood flow
• 5-6 L/min up to 21 L/min

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Limitations of the CV during acute exercise

• Priorities
• CNS
• Heart and lungs
• Muscles
• Skin
• How can the heart protect itself and the CNS?
• Cause fatigue by reducing blood flow to the
  muscles

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Meet Wilma and Betty

• Wilma and Betty are twins.
• They weigh the same weight and they are the same
  height.
• They are both 20 years old.

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Wilma and Betty

• They are jogging together at the same pace.
• This is called an absolute workload.
• Another example would be riding a stationary bike
  at the same rpm and same resistance.
• Their VO2s would be similar since they are doing
  the same amount of work

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Cardiovascular

• Wilma and Betty are jogging at an intensity level
  with a VO2 of 2 L/min
• Wilmas heart rate is lower. Why?

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Cardiovascular

• Wilmas submaximal SV is greater but why? (next)

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Myocardial Hypertrophy

• Aerobic training. Thicker walls and greater
  volume
• Strength training. Thicker walls only
• Pathological. Thicker but weaker walls

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Blood Volume

• Who has more RBCs?
• Wilma has 2.4 liters of RBC
• Who has more blood volume?
• Wilma has 5.8 liters of blood
• Who has the higher hematocrit?
• Bettys hematocrit is 44

Betty and Wilma
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Blood Volume

• 5.0 to 5.8 liters of total blood volume (14
  increase)
• 2.2 to 2.4 liters of RBCs (8 increase)
• 2.8 to 4.3 liters of plasma (35 increase)
• Hematocrit Dropped from 44 to 41
• Why?
• A small increase in RBC (8) combined with a
  great increase in plasma (35) results in diluted
  (thinner) blood

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a-vO2 difference and VO2

• Whose submaximal a-vO2 differences is higher?
• Whose maximal a-v O2 difference is higher?

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Other Chronic Differences

• VO2max? Why is it greater in trained individuals?
• Cardiac output
• Heart Rate?
• STROKE VOLUME
• a-v O2 difference

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Chronic Adaptations to Aerobic Exercise

• VO2 max 20 higher
• Q higher at max
• Heart rate lower resting and submax
• Why?
• Increase SV
• Increase parasympathetic stimulation
• HR max slightly lower

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Chronic Adaptations

• SV 20 higher
• Why?
• Larger heart size
• Increase EDV
• Increase blood volume
• Increase contractility
• Increase Ca release in myocardium
• Similar ESV
• Greater ejection fraction due to higher EDV

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Chronic Adaptations

• a-vO2 difference slightly greater
• Why?
• Mitochondria
• Increase in aerobic enzymes
• Citrate synthase
• 3-hydrozyacylCoA dehydrogenase (3-HAD)
• Myoglobin
• Capillaries
• Hemoglobin

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Chronic Adaptations

• Blood lactate levels
• Increase removal.?
• Increase capillaries
• Decrease sympathetic stimulation causes an
  increase blood flow to heart, liver, and type I
  muscle fibers
• Decrease production. Why

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Chronic Adaptations

• Blood Pressure
• Systolic lower resting and submax
• 10 mm Hg decrease
• Diastolic lower maximum
• Why?
• Weight loss
• Reduce sympathetic stimulation
• Other

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Chronic Adaptations

• Blood flow
• Coronary higher at rest, submax, and max.
• Greater SV and lower HR cause a reduction in
  mVO2.
• Greater vascularity only in diseased hearts

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Chronic Adaptations

• Skeletal blood flow
• Increase vasularity (capillaries)
• Increased O2 and fuel delivery
• Decrease resistance ? decrease afterload ?
  increase Q
• Decrease flow at submax exercise
• Compenstated by an increase O2 extraction
• Greater blood flow to skin
• Increase flow at maximal exercise (10)
• Due to greater Q and vasularity

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What limits aerobic exercise?

• Lack of oxygen supply?
• If so, wouldnt they be more anaerobic?
• And, wouldnt the heart also be more anaerobic?
• But an anaerobic heart produces angina
• Maybe the heart and nervous system protect
  themselves from ischemia but limiting the
  activity of the muscles