Upload
rebecca-bradford
View
309
Download
13
Tags:
Embed Size (px)
Citation preview
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.mcgraw-hill.com/sites/9834092339/student_view0/chapter49/alveolar_pressure_changes_during_inspiration_and_expiration.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 powerUnits = 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/minFemale: ~36 ml/kg/min
Trained athletes…Male: 80-90 ml/kg/minFemale: 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 ExerciseIntensity % 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