Transcript Exercise Physiology

Exercise Physiology
Cardiorespiratory Physiology
Cardiovascular System
• Functions:
• Supply muscles & organs with oxygen
• Deliver nutrients to muscles & organs
• Remove metabolic by-products from
active tissues
• Like???
• Functions accomplished due to blood
Heart Structure
• 4 Chambers:
• 2 Atria- receive blood from body; upper chambers
• 2 Ventricles- send blood to body; lower chambers
• Right & Left Sides:
• Right- receives from body & sends blood to lungs;
deoxygenated blood
• Left- receives from lungs & sends blood to body;
oxygenated blood
Heart Structure
Blood Vessels & Blood
• 3 Major Types:
1. Arteries: carry blood away from the heart
2. Capillaries: site of substance exchange
3. Veins: carry blood back to the heart
Blood Vessels & Blood
• Red blood cells contain hemoglobin
• Molecule made of protein & iron
• Capable of bonding to & transporting 4 oxygen
molecules
• Amount of oxygen being transported is dependent upon
partial pressure of oxygen (PO2)
• In lungs, PO2 is high, oxygen binds easily
• Near tissues in body, PO2 is low, oxygen unloads &
allows diffusion
Cardiorespiratory Connection
http://www.youtube.com/watch?v=mH0QTWzU-xI
Respiratory System
• Functions:
• Deliver oxygen to the blood
• Remove carbon dioxide from the blood
• Aid in acid-base (pH) balance of the blood
Respiratory Structures
• Nose & Mouth:
• Filter, humidify, & adjusts temperature of air
• Trachea:
• Passageway for air only
• Bronchi:
• Tubes that allow air to enter the lungs
Respiratory Structures
• Lungs:
• Right (larger) & Left
• Divided into lobes
• Soft & spongy
• Contain alveoli
• Alveoli
• Tiny air sacs
• Site of gas exchange (diffusion)
• Movement of molecules from areas of high
concentration to low concentration until equilibrium
Respiratory Structures
Ventilation
• 2 phases:
• Inspiration- movement of air into the lungs
• Expiration- movement of air out of the lungs
• http://glencoe.mcgrawhill.com/sites/9834092339/student_view0/chapter49/a
lveolar_pressure_changes_during_inspiration_and_e
xpiration.html
Ventilation
• Breathing rate & depth increases with exercise
• Why?
• Not due to need for more oxygen
• Due to need to rid body of carbon dioxide & maintain
blood pH
• Allows for more gas exchange to occur
• Efficiency of gas exchange increases
Gas Exchange
Measuring Heart Rate
• Heart Rate (HR)
• Number of times the heart beats in 1 minute
• Units = bpm (beats per minute)
• Resting HR
• 40 bpm – 70 bpm
• Heart Rate changes due to body’s need to eliminate CO2
• CO2 becomes carbonic acid in the blood & alters pH
• Exercise HR can be 200+ bpm
Measuring Heart Function
• Stroke Volume:
• The amount of blood pumped out of the left ventricle
with each heartbeat
• Units = mL or L
• Cardiac Output:
• The amount of blood pumped into the aorta each
minute
• Units = mL or L per minute
• Cardiac output = stroke volume x heart rate
Measuring Blood Pressure
• Normal = 120/80 mm Hg
• Systolic pressure
• Estimates the heart’s work & pressure against walls
of arteries
• Occurs during ventricular contraction
• Diastolic pressure
• Indicates the blood pressure in the body outside of
the heart
• Occurs during ventricular relaxation
Measuring Cardiorespiratory Function
 VO2 Max:
maximal volume of oxygen that can be
consumed in a given amount of time during
maximal effort
Measures aerobic power
Units = mL of oxygen/kg of body wt/min
VO2 Max
 Peaks between 18-25 years of age
 Sedentary but healthy 20 year old…
Male: ~40 ml/kg/min
Female: ~36 ml/kg/min
 Trained athletes…
Male: 80-90 ml/kg/min
Female: 75-85 ml/kg/min
Measuring Cardiorespiratory Function
• Arterial-Venous Oxygen Difference (a-v O2 difference)
• Difference in the amount of oxygen present in the
blood when it leaves the lungs and when it returns to
the lungs
• Increase in this value reflects more oxygen use
• Example:
• At rest = 4-5 mL O2 /100 mL of blood
• During exercise = 15 mL O2 /100 mL of blood
Immediate Response to Exercise
• Heart Rate: Increases
• Blood Pressure:
• Systolic increases
• Diastolic no change
• Stroke Volume: Increases (to a point)
• Cardiac Output: Increases
• a-v O2 difference: Increases
Immediate Response to Exercise
• Bohr Effect
• Exercise causes body temperature to rise
• Hemoglobin is less effective at holding onto oxygen
• Results in more oxygen being released to working
tissues
Training (Long Term) Effects
• Increased heart size
• Larger atria & ventricles
• Thicker heart wall
• Increases rate of contraction & volume of blood
emptied from chambers per beat
• Results in:
• Decreased resting heart rate
• Increased stroke volume
• Increased cardiac output
Training (Long Term) Effects
• Increased capillarization
• Improved substance exchange
• Reduced risk of cardiac disease & heart attack
• Improvements in a-v O2 difference
• Oxygen extraction from blood improved
• Increases # and activity of mitochondria
• More oxidative phosphorylation
Training (Long Term) Effects
• Increase total blood volume
• Hormone erythropoietin (EPO) stimulates red blood
cell production
• Results in:
• Increased amount of oxygen carried by blood
• Increased oxygen extraction by muscles
• Altitude Training
Prescribing Cardiorespiratory Exercise
• Maximum HR
• 220-Age (in years)
• Exercise intensity is often prescribed as a % of max HR
• Recommendation for typical sedentary adults 70-85%
max HR
• Changes to this range (above, below or within) are
based on goals for exercise
• Relationship between intensity & duration of exercise?
Prescribing Cardiorespiratory Exercise
Intensity
% max HR
Comments
Very Light
< 50%
Often prescribed for elderly exercisers
Light
50-63%
Recovery
Moderate
64-76%
Builds endurance; burns more fat
Hard
77-93%
Appropriate for younger, more physically
fit individuals; burns more carbohydrates
Very Hard
>94%
Should only be used for interval training;
cannot be maintained for long periods of
time
Maximal
100%
Should not be used