EXERCISE AND THE HEART

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					     EXERCISE AND THE HEART
   Acute exercise
    – Single bout of exercise
        Steady State (Submaximal) exercise
        Maximal exercise
   Chronic exercise
    – Months of conditioning or training
    – Differences between training and untrained
      individuals
Cardiovascular Response to Acute
Exercise

 w Heart rate (HR), stroke volume (SV), and cardiac
   .
  output (Q)...
 w Blood flow (and distribution)….
 w Blood pressure …

 w All of the above change during exercise in
  order to meet the increase O2 and energy
  demands of the muscles.
Heart Rate and Acute Exercise

   Why does heart rate increase during acute
    exercise?
   What causes heart rate exercise?
   Why does heart rate level off when the
    exercise intensity levels off?
   What is the relationship between heart and
    exercise intensity?
   How is maximum heart rate estimated?
Heart Rate and Acute Exercise
  Heart
  Rate




             Mile
    Heart Rate and Acute Exercise


 What    causes heart rate to increase?
 Parasympathetic
 Sympathetic
 Catecholamines
    – Epinephrine
    – Norepinephrine
Heart Rate and Acute Exercise


 Why does heart rate level off when the
  exercise intensity levels off?
 O2 supply = O2 demand
Heart Rate and Acute Exercise
Heart Rate and Acute Maximal Exercise


                              What is the
                              relationship
                          between heart rate
                             and exercise
                         intensity? Or, how
                         is heart affected by
                            the intensity of
                               exercise?
    Heart Rate and Acute Maximal Exercise

    Can be estimated: HRmax =
     220 – age in years
     –   For 20 year old, HRmax =
         200
     –   For 43 year old, HRmax =
         177
    Other formulas:
    210 – (0.65 x age)
    208 – (0.70 x age)
     –   For 20 year old, HRmax =
         194
     –   For 43 year old, HRmax =
         178
    202 – (0.72 x age)
    Stroke Volume and Acute Exercise


 Why does stroke volume increase during exercise?
 What causes stroke volume to increase during
  exercise?
 Why does stroke volume stop increasing, or reach
  its maximum, before a person reaches their
  maximal effort?
 What is cardiovascular drift?
    Stroke Volume and Acute Exercise

•   What causes stroke volume to increase during
    exercise? Hint: There is less residual volume
    • What is residual volume?
    • The amount of blood remaining in the heart after a
      contraction. Also called end systolic volume
•   What causes the heart to beat stronger (and thus
    reduce the residual volume) during acute
    exercise?
•   Increase sympathetic stimulation and increases in
    epinephrine and norepinephrine
Stroke Volume and Acute Maximal Exercise


                          Why does stroke
                             volume stop
                            increasing, or
                               reach its
                          maximum, before
                          a person reaches
                           their maximal
                                effort?
    Stroke Volume and Acute Exercise

 What   is cardiovascular drift?
 What happens to the amount of plasma
  as exercise continues? Increase or
  decrease?
 What affect would a decrease in plasma
  volume have on stroke volume?
 If stroke volume decreases, what would
  have to happen to heart rate in order to
  keep blood flow or cardiac output at the
  same level? (see next slide)
Stroke Volume and Acute Exercise
Cardiovascular Drift
Cardiac Output and Acute Exercise


  If heart rate and stroke volume increase
   during exercise, what will happen to
   cardiac output?
  Why is it important that cardiac output
   increases during exercise?
  How can even more blood be sent to the
   exercising muscles?
Cardiac Output and Acute Maximal Exercise
If heart rate and stroke volume increase during exercise, what will
happen to cardiac output?




Why is it
important that
cardiac output
increases during
exercise?
Summary of HR, SV and Q During Acute
Exercise

                      Heart rate Stroke volume   Cardiac output
Activity             (beats/min)    (ml/beat)       (L/min)

 Resting (supine)        55          95               5.2

 Resting (standing       60          70               4.2
  and sitting)
 Running                190         130              24.7
 Cycling                185         120              22.2
 Swimming               170         135              22.9
    Blood Flow and Acute Exercise

   How can even more blood be sent to the
    exercising muscles?.
Blood Flow and Acute Exercise
    Blood Flow and Acute Exercise

 How can even more blood be sent to the
  exercising muscles?
 Vasodilation of arterioles near exercising
  muscles
    – Waste products
   Vasoconstriction of arterioles near non-
    exercising muscles and organs.
    – Sympathetic stimulation
Blood Pressure During Acute Exercise


 How would an increase in blood flow
  through the blood vessels affect blood
  pressure?
 How would vasodilation of the blood
  vessels affect blood pressure?
Blood Pressure During Acute Exercise


Cardiovascular Endurance Exercise

 What affect does CV exercise have on
  systolic blood pressure?
 Why?
 What affect does CV exercise have on
  diastolic blood pressure?
 Why?
Blood Pressure During Acute Exercise

Resistance Exercise

 How does resistance exercise affect
  blood pressure?
 Why?
 Some BP increases are attributed to the
  Valsalva maneuver
Blood Pressure During Acute Exercise
Blood Flow and Acute Exercise

   What is responsible for the increase blood flow
    to the muscles during exercise?
    – Increased cardiac output
        Increased heart rate and stroke volume
    – Redistribution of blood flow
        Vasodilation and vasoconstriction
 What will happen to aerobic energy production
  as more blood is supplied to the muscles during
  exercise
 How is aerobic energy production measured?
   Oxygen consumption or VO2
          Oxygen Consumption

    VO2 is a measure of how much and how fast
     O2 is used to make energy (ATP)
    In order for VO2 to increase what must change
     inside the body?
1.   Increase cardiac output
2.   Increase extraction of oxygen from the blood
    Therefore VO2 = cardiac output x the amount
     of oxygen extracted from the blood
            Oxygen Consumption

 Oxygen Extraction at
  Rest
 Arteries
    – 20 ml or oxygen in every
      100 ml of arterial blood
   Veins
    – 15 ml/100 ml of blood.
 How much oxygen did
  the muscles use?
 This amount is call the
  a-vO2 difference.
        Oxygen Consumption

 Cardiac output (Q) = how quickly an amount of
  blood (e.g. 100 ml) flows to the muscles
 a-v O2 difference = amount oxygen of that 100
  ml is extracted (or removed) from the blood
 VO2 = Q x a-v O2 difference
 VO2 is how aerobic energy production is
  measured
       Oxygen Consumption

 What does VO2 tell us?
 How much oxygen is being used to make
  energy
 Resting VO2 = 3.5 ml/kg/min
 Exercise VO2
 Maximal VO2 (VO2 max)
                  Exercise VO2

                         = 57 ml/kg/min
VO2 (ml/kg/min)




                               Running = 38 ml/kg/min


                               Jogging = 24 ml/kg/min

                               Walking = 16 ml/kg/min




                        Time
                     Maximal VO2
Results from a graded treadmill test where treadmill speed and
elevation are increased every minute.

 TIME     HR      VO2   VO2/KG    VCO2     R       VE       %EO2    %ECO2
   1        125    2096   35.52     1577    0.75    37.70     15.78    4.20
   2        138    2383   40.39     2000    0.84    45.30     15.97    4.45
   3        140    2611   44.26     2295    0.88    51.70     16.13    4.47
   4        147    2735   46.35     2333    0.85    53.70     15.88    4.58
   5        155    2957   50.12     2677    0.91    58.70     16.10    4.61
   6        164    3257   55.20     2934    0.90    62.30     15.92    4.76
   7        168    3270   55.42     3041    0.93    63.90     16.00    4.81
   8        174    3583   60.74     3481    0.97    76.00     16.36    4.63
   9        180    3813   64.63     3848    1.01    85.50     16.58    4.56
  10        186    3999   67.77     4245    1.06    92.50     16.68    4.65
  11        192    4181   67.86     4704    1.13   111.60     17.17    4.29
               Maximal VO2 Values
PERCENTILE       20-29        30-39         40-49        50-59          60+

    Men
     90             51.4         50.4          48.2          45.3          42.5
     50             42.5         41.0          38.1          35.2          31.8
     10             34.5         32.5          30.9          28.0          23.1
  Women
     90             44.2         41.0          39.5          35.2          35.2
     50             35.2         33.8          30.9          28.2          25.8
     10             28.4         26.5          25.1          22.3          20.8

►Average values for 18-22 year olds: 44 to 50 ml · kg-1 · min-1 for males and 38
to 42 ml · kg-1 · min-1 for females

				
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posted:11/24/2011
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