Cardiovascular Control During Exercise And Adaptations Flashcards
Neural Control of the CV System
- Cerebral cortex (central command)
- Cardiovascular control center (CVC)
- Peripheral afferents
- Baroreceptors
- Chemoreceptors
- Muscle Afferents
Cardiovascular Control Center
- 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
- Stimulates CVC Center
Stoke Volume and Cardiac Output
- 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
-
SV = EDV/ESV
- Cardiac Output (Q)
- Volume bloof pumped/min from L ventricle
- Q = SV x HR
Ejection Fraction (EF)
Portion of blood pumped out of the left ventricle after each beat
EF = SV/EDV
Average is 60% at rest
Blood Pressure - Resting
In people 60 and older with no Diabetes and no CKD, Goal SBP <150 and Goal DBP <90
Blood Pressure
- 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
BP and Exercise
- 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
- Hypertension vs Normal
Cardiac Medications
- 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?
- Diuretics
Abnormal BP and Exercise
- Decrease in systolic BP or failure to increase BP with increase workloads
- Exercise-induced hypotension
- CAD
- Valvular heart disease
- Cardiomyopathies
- Arrhythmias
Hematocrit
Ratio of formed elements to total blood volume
Female: 35-47%
Male 42-52%
Cardiovascular Response to Acute Exercise
- 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
Resting & Max HR
- 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)
Cardiac Output (Q)
Q is linear
SV x HR
HR makes it linear; HEART RATE IS LINEAR
More fitness
Frank Starling – “Preload”
- (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
What is the relationship between Q and workloads?
Linear
What are max values for Q?
20-40 L/min
Arterial Venous Oxygen Difference
- 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
Vascular Smooth Muscle
- Controlled by metabolic and neural/hormonal factors:
- Nitric Oxide (NO)
- Vasodialation – Increase bloow flow
- NE and EP (Beta2 receptors on smooth muscle)
- Vasodialation
- Nitric Oxide (NO)
Poisseuille’s Law
- 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
- Example: Radius decreases by half
Regional Blood Flow
- 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
Rate-Pressure Product – RPP
- 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.
Example of clinical significance
With Training: rest and submax levels of RPP are decreased
What are the functional limitations of this statement?
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
Changes in Q and VO2max with Training
Higher VO2max with more training
Cardiac Output (Q) increases with training
Relative change depends on how fit you are
Differences in Heart Size, HR and SV
More training = lower HR
SV is greater after training
SV gets larger therefore Q greater
SV Graph
Training - EDV
More blood in diastole
Higher preload coming back
Training - ESV
More blood at rest in ventricle at end of systole
At higher loads we have less
Training - EF
With training get a greater EF
Resting HR
Variable!
Sedentary individuals can decrease RHR by 1 beat/min per week during initial training
Aerobic elite athletes have lower HR
HR Recovery period
- 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
BP and Training
- 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
Heritage Family Study
- VO2 increases with exercise
- 18% average increase VO2max
- Attributed change due to genetics (47%)
Adaptations to Aerobic Training
- 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
Capillarization of Muscles
- Increase up to 15% of capillaries in trained individuals
- Angiogenesis: Creation of capillaries
- Transport and utilize more O2
Total Energy Change Training
Same amount of work to do the exercise trained or untrained
Receive higher levels of CHO as energy preexercise than postexercise.
Adaptations affecting energy sources
- 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
Use of Energy Sources with increasing intensity
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
Aerobic training considerations
- Volume
- Frequency and duration
- Intensity
- Interval or continuous training
- Interval training is superior for aerobic
- Interval or continuous training
Training Volume and VO2max
- Training effect occurs initially but hits a point in which everyone plateaus
- Genetic predisposition represents the difference between the two runners
Anaerobic Training
- 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
Lactate Threshold
- LT shifts to the right with training
- LT would occur at a higher workload with training
