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 (PO 2 ) In lungs, PO 2 is high, oxygen binds easily Near tissues in body, PO 2 is low, oxygen unloads & allows diffusion

Cardiorespiratory Connection

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 hill.com/sites/ /student_view0/chapter49/a lveolar_pressure_changes_during_inspiration_and_e xpiration.htmlhttp://glencoe.mcgraw- hill.com/sites/ /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 CO 2 CO 2 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  VO 2 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

VO 2 Max  Peaks between years of age  Sedentary but healthy 20 year old…  Male: ~40 ml/kg/min  Female: ~36 ml/kg/min  Trained athletes…  Male: ml/kg/min  Female: ml/kg/min

Measuring Cardiorespiratory Function Arterial-Venous Oxygen Difference (a-v O 2 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 O 2 /100 mL of blood During exercise = 15 mL O 2 /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 O 2 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 O 2 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 HRComments Very Light< 50%Often prescribed for elderly exercisers Light50-63%Recovery Moderate64-76%Builds endurance; burns more fat Hard77-93%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 Maximal100%Should not be used