Cardiovascular Control During Exercise And Adaptations

Question 1

Neural Control of the CV System

Answer 1

• Cerebral cortex (central command)
• Cardiovascular control center (CVC)
• Peripheral afferents
  
  • Baroreceptors
  • Chemoreceptors
  • Muscle Afferents

Question 2

Cardiovascular Control Center

Answer 2

• Cells in reticular formation of brain stem
• Vasomotor center (4 areas)
  
  • Pressor Area – Increases BP (vascoconstriction)
  • Depressor Area – Decreases BP – Inhibits vasoconstriction and HR)
  • Cardioaccelerator center – Increases HR
  • Cardioinhibitory center – Decreases heart activity, Vagus N.
• Exercise
  
  • Stimulates CVC Center
    
    • Increase HR
    • Increase Cardiac conduction
    • Increase impulse conduction
    • Vasoconstriction
  • Decreases parasympathetic influence

Question 3

Stoke Volume and Cardiac Output

Answer 3

• Stroke Volume
  
  • SV = EDV/ESV
    
    • EDV = Blood filling in diastole just before systole
    • ESV = Volume of blood at the end of systole (contraction)
  • SV= Volume blood ejected/contraction
• Cardiac Output (Q)
  
  • Volume bloof pumped/min from L ventricle
  • Q = SV x HR

Question 4

Ejection Fraction (EF)

Answer 4

Portion of blood pumped out of the left ventricle after each beat

EF = SV/EDV

Average is 60% at rest

Question 5

Blood Pressure - Resting

Answer 5

In people 60 and older with no Diabetes and no CKD, Goal SBP <150 and Goal DBP <90

Question 6

Blood Pressure

Answer 6

• BP may range during exercise testing. Make a clinical decision on factors don’t automatically stop the test if you see these values.
  
  • >250mm Hg Systolic
  • >115 mm Hg Diastolic
• Linear increase in Systolic BP with increased workloads (Same goes for HR)
  
  • Due to Increased cardiac output
  • ~10 mm Hg per MET
  • BP can be increase significantly during resistance training and pooing due to abdominal pressure.
    
    • Must be careful as massive release of blood back to the system can dislodge blood clots

Question 7

BP and Exercise

Answer 7

• Diastolic BP
  
  • Remains the same or will decrease slightly
  • Due to decrease in TPR (vasodialation)
• Systolic BP
  
  • Linear increase with increase workloads
• Post exercise response 
  
  • Decrease in systolic BP
  • Lower than pretest BP for several hours (12-18) based on duration and intensity
    
    • The more exercise the greater the effect
    • The higher the BP the lower the BP after exercise
      
      • Hypertension vs Normal
        
        • Hypertension drops more

Question 8

Cardiac Medications

Answer 8

• Medication and BP
  
  • Diuretics
    
    • Pee more
  • Beta Blocker
    
    • Slow Heart Rate
  • ACE inhibitor
    
    • Decreased reabsorption of NA and water
  • Ca+
    
    • Decreased reabsorption of NA and water?

Question 9

Abnormal BP and Exercise

Answer 9

• Decrease in systolic BP or failure to increase BP with increase workloads
• Exercise-induced hypotension
  
  • CAD
  • Valvular heart disease
  • Cardiomyopathies
  • Arrhythmias

Question 10

Hematocrit

Answer 10

Ratio of formed elements to total blood volume

Female: 35-47%

Male 42-52%

Question 11

Cardiovascular Response to Acute Exercise

Answer 11

• HR increases as workload  increases
• SV is NOT linear; Starts linear and starts curving depending on training
  
  • The more training the less of a curve; heart is more efficient at pumping

Question 12

Resting & Max HR

Answer 12

• Normal: 60-80
• >100 Tachycardia
• <60 Bradycardia
• Max Heart Rate
  
  • HRmax = 220 – age in years [sd + or – 10-12] OR
  • HRmax = 208 - (0.7 x age)

Question 13

Cardiac Output (Q)

Answer 13

Q is linear

SV x HR

HR makes it linear; HEART RATE IS LINEAR

More fitness 

Question 14

Frank Starling – “Preload”

Answer 14

• (Amount of blood that is in the heart before contraction)
  
  • More blood -> more stretch -> more contraction
  • Sympathetic (Ionotropic)
    
    • Ionotropic = stronger
  • Decrease in TPR (Total Peripheral Resistance)
  • Resting Value ~ 5.0 L/min

Question 15

What is the relationship between Q and workloads?

Answer 15

Linear

Question 16

What are max values for Q?

Answer 16

20-40 L/min

Question 17

Arterial Venous Oxygen Difference

Answer 17

• Amount of oxygen extracted from the blood
  
  • At capillary level
• Fick Equation
  
  • VO2 = Q x a-VO2diff
• Arterial = 20
• Venous = 15
• AVO2 difference
  
  • Extract ~5ml O2/100mL

Question 18

Vascular Smooth Muscle

Answer 18

• Controlled by metabolic and neural/hormonal factors:
  
  • Nitric Oxide (NO)
    
    • Vasodialation – Increase bloow flow
  • NE and EP (Beta2 receptors on smooth muscle)
    
    • Vasodialation

Question 19

Poisseuille’s Law

Answer 19

• Flow varies to the r^4
  
  • Example: Radius decreases by half
    
    • Flow [1/16 of original value]
  • Small decrease in radius
    
    • Huge decrease in blood flow

Question 20

Regional Blood Flow

Answer 20

• Blood flow to brain is critical – CNS increased by 25%
• Heart > 3.5 fold increase in blood flow
  
  • AVO2 for cardiac cell = Nearly 200%
  • Cannot increase O2 extraction
  • Must increase flow
  • Control mostly metabolic and autoregulation

Question 21

Rate-Pressure Product – RPP

Answer 21

• Indirect measure of myocardial O2 consumption
• RPP = HR x Systolic BP
• Range 
  
  • Rest and submax levels are decreased with training; Max has no change
  • Rest
    
    • 5,400-14,000
  • Max
    
    • 25,000 – 40,000
• With Training: Rest and submax levels are decreased; max does not change.

Question 22

Example of clinical significance

With Training: rest and submax levels of RPP are decreased

What are the functional limitations of this statement?

Answer 22

Symptoms come on when they reach a multiplicitant of that HR and Systolic

The lower the functional capacity the larger the impact one has on fitness

Question 23

Changes in Q and VO2max with Training

Answer 23

Higher VO2max with more training

Cardiac Output (Q) increases with training

Relative change depends on how fit you are

Question 24

Differences in Heart Size, HR and SV

Answer 24

More training = lower HR

SV is greater after training 

SV gets larger therefore Q greater

SV Graph

Question 25

Training - EDV

Answer 25

More blood in diastole Higher preload coming back

Question 26

Training - ESV

Answer 26

More blood at rest in ventricle at end of systole At higher loads we have less

Question 27

Training - EF

Answer 27

With training get a greater EF

Question 28

Resting HR

Answer 28

Variable! Sedentary individuals can decrease RHR by 1 beat/min per week during initial training Aerobic elite athletes have lower HR

Question 29

HR Recovery period

Answer 29

* The time after exercise that it takes your heart to return to its resting rate * **With training, HR returns to resting level more quickly after exercise** * CV Risk if too slow * Recovery is a better indication of cardiovascular status than submax test

Question 30

BP and Training

Answer 30

* If **hypertensive or pre-HTN** * **Resting BP is lowered for both SBP and DBP** * Submax * BP is less at each submax exercise work rate * Max * SBP is higher (can do more work); DBP is lower

Question 31

Heritage Family Study

Answer 31

* VO2 increases with exercise * 18% average increase VO2max  * Attributed change due to genetics (47%)

Question 32

Adaptations to Aerobic Training

Answer 32

* Increase number, size, and oxidative enzymes (mitochondria) * Increase number of capillaries in skeletal muscle * Increase myoglobin content of muscles (75-80%) * Small transition of muscle fiber type * Increase % slow twitch * Decrease % fast twitch * Genetics * Efficiency of energy production

Question 33

Capillarization of Muscles

Answer 33

* **Increase up to 15% of capillaries in trained individuals** * Angiogenesis: Creation of capillaries * Transport and utilize more O2

Question 34

Total Energy Change Training

Answer 34

Same amount of work to do the exercise trained or untrained Receive higher levels of CHO as energy preexercise than postexercise.

Question 35

Adaptations affecting energy sources

Answer 35

* Trained * Use more glycogen and triglycerides * FFAs are better mobilized and more accessible * Ability to oxidize fat increases * Ability to rely on fat store conserves glycogen during prolonged exercise

Question 36

Use of Energy Sources with increasing intensity

Answer 36

Fat becomes less of an energy source as you get closer to max Carbohydrates become more of an energy source as you get closer to max With training we see a shift in the cross over point to the right Fats can be used at a higher period of time at a higher intensity

Question 37

Aerobic training considerations

Answer 37

* Volume * Frequency and duration * Intensity * Interval or continuous training * Interval training is superior for aerobic

Question 38

Training Volume and VO2max

Answer 38

* Training effect occurs initially but hits a point in which everyone plateaus * Genetic predisposition represents the difference between the two runners

Question 39

Anaerobic Training

Answer 39

* Increase in muscular strength, **increases fast twitch** muscles * Slight increase in **ATP-PCr and glycolytic enzymes** * Increased muscle **buffering capacity** * If you overload the system, increase strength and adapt until the body hits a plateau

Question 40

Lactate Threshold

Answer 40

* LT shifts to the right with training * LT would occur at a higher workload with training