cardiovascular changes

1. Cardiovascular Adaptations
to Aerobic Endurance
Training

2. Cardiac Dimensions
• Cardiac dimensions and mass increase with endurance training .These changes are
associated with high cardiac outputs during sustained dynamic aerobic exercise.
• Endurance training exposes the heart to conditions of increased ventricular filling
with subsequent high stroke volume and cardiac output.This chronic exposure to
high levels of ventricular filling (large left ventricular end diastolic volume) is known
as volume overload. Chronic volume overload results in an increased left ventricular
end diastolic diameter and left ventricular mass

3. Coronary Blood Flow
• Endurance training results in an increase in the size of the coronary vascular
bed .This increase in capillarization may be related to an increase in heart
weight as a result of training.
• Exercise training can lead to the development of coronary collateral
circulation, defined as the ability to supply areas of the myocardium with
blood through small new growth anastomoses

4. • The internal diameter of the coronary arteries also may be increased by
endurance training.
• Habitual exercise is related to a larger cross-sectional arterial size

5. BloodVolume
• Increases as a result of endurance training. Highly trained endurance
athletes have a 25% larger blood volume than untrained subjects.The
increase in blood volume is primarily due to an expansion of plasma volume.
• Changes in plasma volume occur soon after the initiation of an endurance
training program, with changes between 8% and 10% occurring within the
first week followed by a plateauing of plasma volume. For up to 10 days of
training an expansion of plasma volume accounts for changes in blood
volume, with little or no change in red blood cell mass

6. • Tests of hematocrit and hemoglobin concentration during this time period are
often low, because the red blood cells and hemoglobin are diluted by the larger
plasma volume.
• At times this condition has been labeled as sports anemia, but this term is a
misnomer, since the number of red blood cells is almost the same or may actually
be increased above pretraining levels.
• Thus, this condition represents no reason for alarm and may be beneficial.The
lower hematocrit as a result of elevated plasma volume and normal or slightly
elevated number of red blood cells means that the blood is less viscous, which
decreases resistance to flow and facilitates the transportation of oxygen

7. Cardiac Output
• Resting cardiac output is not changed following a training program; however, it is
achieved by a larger stroke volume and a lower heart rate. Cardiac output at an
absolute submaximal workload is decreased or unchanged with training .
• Maximal cardiac output is increased at maximal levels of exercise following an
endurance exercise training program .
• The increase in cardiac output seen at maximal exercise is the result of an increase
in stroke volume, since maximal heart rate does not change with training to a
degree that has any physiological meaning.The magnitude of the increase in
cardiac output depends on the level of training. Elite endurance athletes may have
cardiac output values in excess of 35 L·min-1

8. StrokeVolume
• Endurance training results in an increased stroke volume at rest, during
submaximal exercise, and during maximal exercise.The increase in stroke
volume results from increased plasma volume, increased cardiac
dimensions, increased venous return, and an enhanced ability of the
ventricle to stretch and accommodate increased venous return.
• Since several of these are structural changes, they will exert their influence
whether the individual is resting or working

9. • Enhanced ventricular filling (increased LVEDV) and emptying (decreased
LVESV) both contribute to the augmented stroke volume in these highly
trained athletes, although ventricular filling appears to have the greater
influence.

10. Heart Rate
• Resting heart rate is lower following endurance training . Although
bradycardia is technically defined as a resting heart rate of less than 60
b·min-1, the term is sometimes used to mean the reduction in resting heart
rate that occurs as a result of exercise training. Bradycardia is one of the
classic and most easily assessed indicators of training adaptation.The heart
rate response to an absolute submaximal amount of work is significantly
reduced following endurance training. Maximal heart rate is unchanged or
slightly decreased (2–3 b·min-1) with endurance training

11. Maximal Oxygen Consumption
• Maximal oxygen consumption (O2max) increases as a result of endurance training .The
magnitude of the increase depends on the type of program followed. Improvements of 30%
are commonly reported, with improvements of 15% routinely found for training programs
that meet the recommendations of the ACSM .There are rapid improvements in O2max
during the first 2 months of an endurance training program. Following this period,
improvements continue to occur, but at a slower rate.This pattern appears to be
independent of gender and P.400
• is consistent over a wide age range, although elderly individuals may take longer to adapt
to endurance training

12. • The improvement in O2max is the result of central and peripheral
cardiovascular adaptations. Recall that O2max can be calculated as the
product of cardiac output and arteriovenous oxygen difference (a-vO2 diff)

13. • Increased maximal cardiac output as a result of endurance training was
discussed in a previous subsection, and it represents a central adaptation
that supports the training-induced improvement in O2max.The a-vO2 diff
reflects oxygen extraction by the working tissue and thus represents a
peripheral adaptation that supports the improvement in O2max .The
changes in cardiac output are a more consistent training adaptation than
the changes in a-vO2 diff, and stroke volume appears to be the principal
factor in the increase in cardiac output

14. • Athletes whose performance depends on the ability of the cardiovascular
system to sustain dynamic exercise consistently have higher O2max values
than athletes whose sport performance is based primarily on motor skills

15. Blood Pressure
• there is little or no change in arterial blood pressure (SBP, DBP, MAP) at rest,
during submaximal exercise, or during maximal exercise in normotensive
individuals following an endurance training program. However, because the
maximal amount of work that can be done increases with exercise training,
a trained individual is capable of doing more work.Thus, maximal systolic
blood pressure may be higher for this individual at maximal exercise.This
difference is usually small between sedentary and normally fit individuals.

16. Total Peripheral Resistance
• Resistance is unchanged at rest or during an absolute submaximal workload
following a training program
• reduction in total peripheral resistance occurs in athletes at maximal
exercise. For this reason, athletes can generate significantly higher cardiac
outputs at similar arterial pressures during maximal exercise. Much of the
additional decrease in the total peripheral resistance at maximal exercise is
due to the increased capillarization of the skeletal muscle

18. Muscle Blood Flow
• Muscle blood flow is unchanged at rest following exercise training. Active
muscle blood flow increases during maximal exercise as a result of
endurance training.The effect of endurance training on muscle blood flow
at submaximal levels is unclear

19. Rate-Pressure Product
• Myocardial oxygen consumption, indicated by the rate-pressure product, is
lower at rest and during submaximal exercise following endurance training.
This result reflects the greater efficiency of the heart, since fewer
contractions are necessary to eject the same amount of blood during
submaximal exercise following an endurance training program . Because
maximal heart rate is unchanged and systolic blood pressure is either
unchanged or increases slightly with exercise training, it follows that the
maximal rate-pressure product is unchanged or increases slightly following
a training program.

20. Cardiovascular Adaptations to Dynamic
ResistanceTraining