Cardiovascular
System and Exercise
Five Functions
• During exercise the cardiovascular system has
5 functions:
1) Deliver oxygen to working muscles
2) Oxygenates blood by returning it to the lungs
3) Transports heat from the core to the skin
4) Delivers nutrients and fuel to active tissues
5) Transports hormones
Effect on the Cardio-Respiratory System
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O2 demand increases
Metabolic process speeds up
More waste created
More nutrients used
Increase body temperature
For your body to perform as well as possible these
changes must be regulated by the cardiovascular
system
How the cardiovascular system
responds to exercise
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Heart rate
Stroke volume
Cardiac output
Blood flow
Blood pressure
Blood
Heart Rate and Exercise
• Resting HR is 60-80 bpm in normal, healthy
adults
• Elite endurance athletes can have a resting HR
as low as 28-40 bpm
• Anticipatory response: HR increases before
exercise even starts (S. N. S.)
• Once exercise starts HR increases in direct
relation of exercise intensity until max. HR is
reached
• Max HR= 220 - age
Heart Rate and Exercise
• Steady-state HR: when exercise intensity is
constant the HR will level off
– Due to demands of tissues is met
• Cardiac drift: HR increases after it levels off
due to increase in body temperature
Stroke Volume and Exercise
• Amount of blood ejected per beat
• Increases with exercise intensity
proportionally
• Increases from 50-70 ml/beat at rest to 110130 ml/beat during exercises
• Will increase during exercise at the beginning
• Plateaus at a point and remains there until
exhaustion
Stroke Volume and Exercise
• Why does stroke volume increase with the onset
of exercise?
– Left ventricle fills more completely
– Stretches further and the contraction to pump the
blood out into the body is more forceful
– This is known as the FRANK-STARLING MECHANISM
• Increases until the you reach approx. 50% of your
VO2 max
Cardiac Output (Q) and Exercise
• Remember Q= SV x HR
• It makes sense that during exercise Q will
increase
– At rest Q= 5L/min and can go up to 20-40L/min
during exercise
• Your cardiac output at rest will not increase
with exercise because as you increase your
aerobic endurance your SV increases and your
resting HR decreases!
Blood Flow and exercise
• An increase in blood flow goes to the muscles
during exercises
• For this to happen less blood goes to internal
organs
– This is why you are told not to eat right before
exercise (up to a few hours)
Blood Pressure and Exercise
• Systolic blood pressure: increases during
exercise up to 200 mmHg
– WHY?
• Systolic blood pressure is the pressure during
contraction of the heart
• Diastolic blood pressure: remains fairly similar
to rest as during exercise.
Blood and exercise
• Blood plasma volume decreases with exercise
• Increase of hemoglobin concentration
– No increase in RBC just concentration
– Allows more oxygen to be carried in the blood
• You can use the amount of oxygen in arterial
and venous blood to help figure out the
oxygen consumption (VO2) used in exercise
Developing a Cardiorespiratory
Endurance Program
• Setting goals
• Applying the FITT equation
– Frequency
– Intensity
– Time
– Type of activity
Frequency of Training
• Train 3–5 days per week
• Beginners should start with 3 and work up to 5
days per week
Intensity of Training
• Target heart rate zone
– Estimate your maximum heart rate (MHR)
• 220 – your age = MHR
– Multiply your MHR by 65% and 85%
• People who are unfit should start at 55% of MHR
– Example: 19-year-old
• MHR = 220 – 19 = 201
• 65% training intensity = 0.65 X 201 = 131 bpm
• 85% training intensity = 0.85 X 201 = 171bpm
Time (Duration) of Training
• Total of 20–60 minutes is recommended
• One single session or multiple sessions of
10 minutes or more
• Different intensity levels require different
durations
– High-intensity activity = 20 minutes
– Low-to-moderate-intensity activity = 45–60
minutes
Type of Training or Exercise
• What type of exercise or training will you do?
• Specificity: refers to the specific PA chosen to
improve a component of health related fitness
• CV/aerobic endurance training, plyometrics
training, muscular endurance/strength
training, sport specific training etc...
Warming Up
and Cooling Down
• Warming Up (5–10 minutes)
–Muscles work better when warmed up
–Redirect blood flow to working muscles
–Spread synovial fluid
• Cooling down (5–10 minutes)
–Blood flow and respiration return to
normal
Building Cardiorespiratory Fitness
• Rate of improvement depends on age, health
status, initial level of fitness, and motivation
• Initial phase (1–4 weeks): 3–4 days per week,
low end of target heart rate zone, 20–30
minutes
• Improvement phase (2–6 months): 3–5 days
per week, middle to upper end of target heart
rate zone, 25–40 minutes
Maintaining Cardiorespiratory Fitness
• Continue to exercise at the same intensity on
3 nonconsecutive days per week
• If you have to stop, start the program again at
a lower level
• Cross-training maintains motivation
Hot Weather and Heat Stress
• Dehydration = excessive loss of fluid
• Heat cramps = sudden development of muscle
spasms and pain
• Heat exhaustion = heat illness related to
dehydration from exertion in hot weather
• Heat stroke = a severe and often fatal heat
illness characterized by significantly elevated
core body temperature
Preventing Heat Illness
– Use caution in high heat or humidity (over 80°F
and/or 60% humidity); lower your intensity and/or
add rest breaks
– Exercise morning or evening
– Drink plenty of fluids; check weight before and
after exercise
– Avoid supplements and beverages containing
stimulants
– Wear clothing that “breaths”
– Slow down or stop if you feel uncomfortable
Heat Index
Exercise in Cold Weather
• Hypothermia = low body temperature due to
exposure to cold conditions
• Frostbite = freezing of body tissues
characterized by pallor, numbness, and a loss
of cold sensation
• Prevention:
– Don’t stay out in very cold temperatures (consult
wind chill values)
– Wear appropriate clothing
Wind Chill
Final thoughts on CV and exercise
• Benefits to your cardiovascular system from
endurance exercise:
– Increase heart muscle in ventricles
– Decrease resting heart rate
– Increase resting stroke volume
– Better working capillaries and blood vessels
– Decrease blood pressure rate at rest