1. health and fitness
2. exercise

Exercise Physiology
MAP = CO x TPR
Cardiac output
Structure of the heart
Cardiac cycle
Control of heart rate
Control of stroke volume
Total peripheral resistance
Functions of vessels
Local control of resistance
Central control of resistance
Regulation of CO and TPR
Cardiovascular changes during exercise
The Cardiac Cycle
Diastole
Systole
 ___________ phase  _________ phase
Fig 9.5
Definitions
• Systolic Blood Pressure (SBP) pressure measured in brachial
artery during systole (ventricular emptying and ventricular
contraction period)
• Diastolic Blood Pressure (DBP) pressure measured
in brachial
artery during diastole (ventricular filling and ventricular
relaxation)
• Mean Arterial Pressure (MAP) "average" pressure throughout the
cardiac cycle against the walls of the proximal systemic
arteries (aorta)
• estimated as:
MAP = DBP + 1/3(SBP – DBP)
• Total Peripheral Resistance (TPR) - the sum of all forces that
oppose blood flow
•
•
•
Length of vasculature
Blood viscosity
Vessel radius
TPR = ( MAP - MVP)
CO
Factors That Influence Arterial
Blood Pressure
Fig 9.8
THE CARDIAC CYCLE
LATE DIASTOLE
DIASTOLE
ISOMETRIC
VENTRICULAR
RELAXATION
VENTRICULAR
EJECTION
ATRIAL
SYSTOLE
ISOMETRIC VENTRICULAR
CONTRACTION
PRELOAD AND AFTERLOAD IN THE
HEART
INCREASE IN FILLING
PRESSURE=INCREASED PRELOAD
 PRELOAD REFERS TO END
DIASTOLIC VOLUME.
 AFTERLOAD IS THE AORTIC
PRESSURE DURING THE EJECTION
PERIOD/AORTIC VALVE OPENING.
 LAPLACES’S LAW & WALL STRESS,
WS = P X R / 2(wall thickness)

THE HEART AS A PUMP

REGULATION OF CARDIAC OUTPUT


Heart Rate via sympathetic & parasympathetic nerves
Stroke Volume



Frank-Starling “Law of the Heart”
Changes in Contractility
MYOCARDIAL CELLS (FIBERS)



Regulation of Contractility
Length-Tension and Volume-Pressure Curves
The Cardiac Function Curve
Autoregulation
(Frank-Starling “Law of the Heart”)
CARDIAC OUTPUT = STROKE VOLUME x HEART RATE
Contractility
Sympathetic
Nervous System
Parasympathetic
Nervous System
Exercise
Cardiorespiratory System At Rest and With
Exercise
Heart Rate
Rest
Exercise
50-90 bpm
Up to 170-210 bpm
Respirations
Rest
Exercise
12-20 breathes per minute
40-60 breathes per minute
Blood Pressure
Rest
Exercise
(Systole=Contraction Diastole=Relaxation)
110/70
175/65
Cardiac Output (SV x HR)
Rest
5 quarts/min.
Exercise
20 or more quarts/min.
Blood flow during exercise
CO is redirected due to:
local metabolic autoregulation in working muscle
causing arteriolar dilation
offset by centrally mediated generalised sympathetic
arteriolar constriction
circulating epinephrine causes
- arteriolar constriction in most tissues
(ie those expressing a receps)
Redistribution of Blood Flow
During Exercise
Fig 9.24
The Effects of Exercise
Immediate Effects:
*Increase in HR, since higher demand for oxygen.
*Increase in BP, as a result of ↑ blood flow.
*Increase in supply, delivery, and use of oxygen by
muscle.
*Increase in body temperature.
*Increase in certain hormones/ neurotransmitters ,
especially epinephrine which stimulates a rise in
all body functions.
*Increase in metabolism.
Effects of Aerobic Training on
Cardiovascular Function
Heart
rate
Stroke volume
a-v O2 difference
Cardiac output
VO2
Systolic blood
pressure
Diastolic blood
pressure
Coronary blood flow
Brain blood flow
Blood volume
Plasma volume
Red blood cell mass
Heart volume
Myocardial Hypertrophy
Aerobic training. Thicker walls
and greater volume
Strength training. Thicker walls
only
Pathological. Thicker but weaker
walls
CV Function and Endurance Training
Increase in EDV (increase chamber size)
Endurance training
Increase myocardial mass (increase
force of contraction)
Strength training
CV Function and Endurance Training
Increase in parasympathetic inhibition of
the SA node (mostly at rest)
Decrease in sympathetic stimulation
(mostly during exercise)
BLOOD PRESSURE
Greatest effect on high blood pressure
Systolic: lower resting and submax
10 mm Hg decrease
Diastolic lower maximum
Why?
Weight loss
Reduce sympathetic stimulation
Other
BLOOD FLOW
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
Redistribution of Blood Flow
During Exercise
Fig 9.24
BLOOD FLOW
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%)
20mmHg
-20mmHg
-40mmHg
20mmHg
0mmHg
20mmHg
0mmHg
+80mmHg
20mmHg 100mmHg

Causes venous distension in legs

 VR,  EDV,  preload,  SV,  CO,  MAP

causes orthostatic (postural) hypotension
Chronic adaptations to Aerobic training
WITHIN THE MUSCLE TISSUE


The following tissue changes occur:
Increased O2 utilisation






increased size and number of mitochondria
Increased myoglobin stores
Increased muscular fuel stores
Increased oxidation of glucose and fats
Decreased utilisation of the anaerobic glycolysis
(LA) system
Muscle fibre type adaptations
Chronic adaptations to Aerobic
training
Cardiac hypertrophy (increased
ventricular volume)
 Increased capillarisation of the heart
muscle
 Increased stroke volume
 Lower resting heart rate
 Lower heart rate during sub max
workloads
 Improved heart rate recovery rates

Chronic adaptations to Aerobic
training
Increased cardiac output at max.
workloads
 Lower blood pressure
 Increased arterio-venous oxygen
difference (a-VO2 diff)
 Increased blood volume and
haemoglobin levels
 Increased capillarisation of skeletal
muscle

Chronic adaptations to Aerobic
training
Changes to blood cholesterol,
triglycerides, lipoprotein levels (L.D.L’s
and H.D.L’s)
 Increased lung ventilation
 Increased max. oxygen uptake (VO2
max)
 Increased anaerobic threshold

Cardiovascular Adjustments
to Exercise
Fig 9.23
LACATE LEVELS
Lactic acid comes to blood from muscles, in which
aerobic resynthesis of energy stores cannot keep
pace with their utilization and a oxygen debt is
being incurred.
With increased production of Lactic acid, the
increase in ventilation and production of carbondioxide remains proportionate, to an extent.
If lactic acid accumulates further , it causes
metabolic acidosis
Accumulation in skeletal muscles causes pain.
The respiratory rate after exercise does not
reach basal levels until the oxygen debt is
paid.
This may take as long as 90 minutes.
Stimulus: elevated lactic acid in blood
When the oxygen debt is paid,
-ATP & phosphorylcreatine resynthesized
-lactic acid is removed – 80% converted to
glycogen, 20% metabolised in to CO2 &
H2O

INCREASED ANAEROBIC OR LACTATE THRESHOLD
As a result of improved O2 delivery & utilisation
a higher lactate threshold (the point where O2
supply cannot keep up with O2 demand) is
developed.
Much higher exercise intensities can therefore
be reached and LA and H+ ion accumulation
is delayed.
The athlete can work harder for longer
Blood Lactate Levels
Effects of Exercise on
Respiration

When talking about
the respiratory
system we are
talking about the
lungs, air passages
and our breathing
(ventilation).
Respiratory Capacities
Figure 13.9
Lung capacities
Total lung capacity: The volume lation in the lungs at maximal in
Tidal volume: The amount of air inhaled in or exhaled out of the lungs
during quiet breathing
Inspiratory reserve volume: The maximal volume that can be inhaled
from the end inspiratory level
Expiratory reserve volume: The maximal volume of air that can be
exhaled from end expiratory position
Residual volume: The volume of air that remains in the lung after a
maximal expiration
Vital capacity: the volume of air exhaled out after the deepest
breathing
Chronic adaptations to Aerobic training
RESPIRATORY ADAPTATIONS
Just as there are cardiovascular
adaptations to AEROBIC training there
are also respiratory adaptations. These
include:
 Increased lung ventilation
 Increased oxygen uptake
 Increased anaerobic or lactate
threshold

Chronic adaptations to Aerobic training
RESPIRATORY ADAPTATIONS



INCREASED LUNG VENTILATION
Aerobic training results in a more efficient
and improved lung ventilation.
At REST and during SUB MAX. work
ventilation may be decreased due to
improved oxygen extraction (pulmonary
diffusion), however during MAX. work
ventilation is increased because of
increased tidal volume and respiratory
frequency.
Respiratory Adaptations
From Aerobic Training





Respiratory system functioning usually does not limit
performance because ventilation can be increased to
a greater extent than cardiovascular function.
Slight increase in Total lung Capacity
Slight decrease in Residual Lung Volume
Increased Tidal Volume at maximal exercise levels
Decreased respiratory rate and pulmonary ventilation
at rest and at submaximal exercise


(RR) decreases because of greater pulmonary efficiency
Increased respiratory rate and pulmonary ventilation
at maximal exercise levels

from increased tidal volume
Cardiorespiratory Endurance

VO2MAX is the best indicator of
cardiorespiratory endurance.
VO2MAX

Maximal O2 consumption by tissues

VO2max = COmax * maximum O2 extraction
by the tissue

Absolute and relative measures.
absolute = l . min-1
 relative = ml . kg-1 . min-1


VO2 = SV x HR x a-vO2diff
Effects on Oxygen Uptake or
Volume of Oxygen Consumed
(VO2)
Oxygen uptake (VO2) is the amount of
oxygen taken up and used by the body. It
reflects the total amount of work being
done by the body.
 During strenuous exercise there can be a
twenty-fold increase in VO2 which
increases linearly with increases in the
intensity of the exercise.

VO2
Training has little effect on resting VO2
Training has little effect on submaximal
VO2
Example, running at 8 mph at a 0% grade
is always at VO2 of ~24.9 ml/kg/min
Training increases maximal VO2
(VO2max)
15-20% (but as high as 50%) increase.
Effects on Oxygen Uptake or
Volume of Oxygen Consumed
(VO2)
As a person approaches exhaustion, his or
her VO2 will reach a maximum above
which it will not increase further.
 This figure is his or her VO2 Maximum;
that is, the largest amount of oxygen that a
person can utilize within a given time (for
example, 50 litres per minute).

VO2max
Training to increase VO2max
Large muscle groups, dynamic activity
20-60 min, 3-5 times/week, 50-85% VO2max
Expected increases in VO2max
15% (average) - 40% (strenuous or
prolonged training)
Greater increase in highly deconditioned or
diseased subjects
Genetic predisposition
Accounts for 40%-66% VO2max
VO2max
Higher Q at max
High a-v 02
difference
Chronic adaptations to Aerobic training
RESPIRATORY ADAPTATIONS



INCREASED MAXIMUM OXYGEN UPTAKE
(VO2 MAX)
VO2 max is improved as a result of aerobic
training – it can be improved between 5 to
30 %. (LIU page 255)
Improvements are a result of:
-Increases in cardiac output
-red blood cell numbers
-a-VO2 diff
- muscle capillarisation
- greater oxygen extraction by muscles
Chronic adaptations to Aerobic training
RESPIRATORY ADAPTATIONS
VO2 MAX
Respiratory Adaptations From
Aerobic Training


Unchanged pulmonary diffusion
at rest and submaximal exercise.
Increased pulmonary diffusion
during maximal exercise.



from increased circulation and
increased ventilation
from more alveoli involved during
maximal exercise
Increased A-VO2 difference
especially at maximal exercise.
Chronic adaptations to Aerobic training
RESPIRATORY ADAPTATIONS




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WORDS to KNOW
Arterio-venous oxygen
difference
Pulmonary diffusion
Lung ventilation
Tidal volume
Respiratory frequency
VO2 max
Lactate threshold
Pulmonary Adaptations:

Most static lung volumes remain
essentially unchanged after training.
Pulmonary Adaptations:

Tidal volume, though unchanged at rest
and during submaximal exercise,
increases with maximal exertion.
Pulmonary Adaptations:

Respiratory rate remains steady at rest,
can decrease slightly with submaximal
exercise, but increases considerably with
maximal exercise after training.
Pulmonary Adaptations:

The combined effect of increased tidal
volume and respiration rate is an increase
in pulmonary ventilation at maximal effort
following training.
Pulmonary Adaptations:

Pulmonary diffusion at maximal work rates
increases, probably because of increased
ventilation and increased lung perfusion.
Pulmonary Adaptations:

a-vO2diff increases with training, reflecting
an increased oxygen extraction by the
tissues and more effective blood
distribution.
Cardiorespiratory Adaptations
From Anaerobic Training



Small increase in cardiorespiratory endurance
Small increase in VO2 Max
Small increases in Stroke Volume
Cardiorespiratory Adaptations
From Resistance Training





Small increase in left ventricle size
Decreased resting heart rate
Decreased submaximal heart rate
Decreased resting blood pressure is greater than
from endurance training
Resistance training has a positive effect on aerobic
endurance but aerobic endurance has a negative
effect on strength, speed and power.




muscular strength is decreased
reaction and movement times are decreased
agility and neuromuscular coordination are decreased
concentration and alterness are decreased
Aerobic Training


The minimum period
for chronic
adaptations to
occur is 6 weeks.
Adaptations from
aerobic training
can occur at the
muscle site and in
the cardiorespiratory systems.
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