Circulatory Responses to Exercise

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Circulatory Responses to Exercise
Chapter 9 Exercise Physiology. Powers
Howley. 6th edition
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Regulation of the Cardiovascular System
Neural Control
SNS vs PNS outflow
Redistribution of blood flow
Mechanical events (muscle action) influence
venous return, help regulate SV Q Neural
neurohormonal more complex
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Regulation of the Cardiovascular System Factors
Affecting Neural Control of CV function
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Cardiovascular Responses to Aerobic
Exercise Short-term, Light to Moderate Submaximal
Aerobic Exercise
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Distribution of cardiac output at rest and during
light exercise
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Long-term, Moderate to Heavy Submaximal Aerobic
Exercise
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Distribution of Q at rest and during heavy
exercise
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Incremental Maximal Exercise
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Distribution of Q at rest and during maximal
exercise
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Application Question

• Are all elevations in
• heart rate equal?
• Does an individual derive the same benefit from
  HR that is elevated by emotion/heat as from HR
  that is elevated by exercise?

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Does an individual derive the same benefit from
HR that is elevated by emotion/heat as from HR
that is elevated by exercise?

• HR can be elevated by a variety of factors
  mediated by the neuronal and hormonal systems
• Exercise, emotion, high temperatures
• Exercise HR responses primary serve as an
  indicator of the training stimulus to the body
  the increase in energy expenditure or metabolism
  (VO2)
• Beta blockers / pacemakers
• Exercise capacity increases although exercise
  induced increase in HR is dampened

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Distribution of VO2max for Males and Females
Differences are 20-30
Differences are 0-15
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VO2max wt for males females across the age
span

• Differences largely explained by
• Heart size
• O2 carrying capacity of blood

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CV response at the completion of fatiguing
resistance exercise
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Application Question

• Why is it not uncommon to hear about individuals
  collapsing and dying of heart attacks while
  shoveling heavy snow?

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Why is it not uncommon to hear about individuals
collapsing and dying of heart attacks while
shoveling heavy snow?

• Upper body exercise ? CV strain
• exemplified by higher HR BP
• disproportionate increase in MVO2 (i.e. reduced
  myocardial efficiency of arm exercise)
• Static (large component) Dynamic resistance
  exercise ? exaggerated increases in BP
• Valsalva manuever and cold air causes a spasm or
  constriction in the coronary arteries

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Age related decline in VO2max in highly active
and sedentary women

• Exercise training can only lessen the age-related
  losses in CV function
• Rate of decline is similar in both groups

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Changes in VO2max based on freq., intensity, and
duration of training and on initial fitness
level
Total volume of work done is more important than
intensity or duration alone
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Comparison of CV response of trained and
untrained individuals to incremental exercise
Due to increase in SV since max HR does not change
VO2max Q x a-VO2 diff
gt Efficiency of the heart
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Effects of reducing exercise freq., intensity,
and duration on maintenance of VO2max
Training 40/day, 6 d/wk
Aerobic fitness level can be maintained by either
continuing or decreasing the volume, as long as
intensity is maintained
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Application Question

• Does a 7-day taper before a competition enhance
  or diminish performance?

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Does a 7-day taper before a competition enhance
or diminish performance?

• Study completed in distance runners
• Run taper group reduced volume to 15 of their
  previous training volume over a 7 day period
• Cycle taper group
• Control group maintained volume
• Completed 10 min submax run GXT TM 5km time
  trial
• Increase in submaximal running economy in run
  taper group no effect in cycle taper or control
  groups
• Key finding Must maintain intensity, and
  specificity of training must be utilized, if
  training volume is drastically reduced