cardiovascular response to training

Question 1

CV system adaptation
acute and chronic

Answer 1

acutely- to increase o2 delivery to working muscles by increasing blood flow to muscles and reducing delivery to low activity tissues
chronically- to deliver more o2 to active muscle mass- more effective o2 delivery during submaximal exercise and increased maximum o2 consumption (vo2 max)

Question 2

CV factors affecting o2 uptake and vo2 max

Answer 2

• cardiac structure and function
• blood (plasma) volume
• blood flow and distribution
• oxygen extraction (AV difference)

Question 3

fick equation

Answer 3

VO2= HR xSV x (a-v) diff
a-v= arterio mixed venous
Q= SV xHR

Question 4

oxygen extraction- avo2 diff

Answer 4

training increases sub maximal and maximal o2 values in muscle
active muscles can utlise o2 more efficiently by increasing oxidative capacity eg higher oxidative enzyme content
can be measured by extracting blood from an artery and a vein while subject is excercising

Question 5

mass of heart

Answer 5

greater in trained athletes and on average is greater in males
highest seen in college wrestlers and shot putters

Question 6

cardiac adaptations- power vs endurance

Answer 6

trends show that power athletes (wrestlers and shot putters) have greater mass and size of left ventricle and septum but lower volume of blood in the LV
endurance athletes are the opposite- higher volume of blood in LV but less mass

Question 7

preload + afterload

Answer 7

pre
amount of blood in ventricle before contraction (EDV), this determines cardiac muscle length before contraction- most important determining factor for preload is venous return

afterload
pressure against which the ventricle must contract (vascular resistance, proportional to arterial mean pressure)
the higher the afterload, less blood will be ejected per heartbeat

Question 8

frank starling mechanism

Answer 8

based on the length tension relationship within the ventricle- greater stretch= greater contraction (increased SV)
Increased Venous Return → Increased End-Diastolic Volume (EDV) → Increased Preload → Enhanced Stretching of Cardiac Muscle Fibers → Increased Force of Contraction → Increased Stroke Volume

Question 9

potential mechanisms for heart changes

Answer 9

left ventricular mass= heavier in athletes
LV volume= higher in endurance athletes–> increased preload= increased stroke volume- eccentric hypertrophy
posterior wall thickness and septal thickness- larger in reisstance athletes–> increased afterload- decreased SV= concentric hypertrophy

Question 10

SV + Q determined

Answer 10

SV- determines by 3 factors= afterload, preload and contractiltity
Q- directly related to venous return and vascular resistance

Question 11

endurance adaptations- SV

Answer 11

increased preload (ventricular filling)–> increased ventricular dimensions
increased diastolic filling time due to bradycardia (slow HR)
increased contractiltity
increased maximal SV

Question 12

adaptations- HR

Answer 12

increased SV = decreased HR for the same Q - at submaximal exercise
different HRs for same intensity
maximal HR is unchanged

Question 13

cardiac output

Answer 13

most significant adaptation is vo2 max
training adaptation at submaximal exercise- Q decreases as increased o2 extraction - due to better muscle oxidative capacity - higher avo2 difference

Question 14

acute blood flow redistrbution

Answer 14

during heavy exercise Q will increase (~25l/min) and the majority ~70-85% of blood will go to muscle (~20l/min)

at rest Q is ~ 5l/min with blood flow to all major sustems and 15-20% to muscle (~0.75l/min)

Question 15

acute blood flow regulation

Answer 15

controlled by:
muscle metabolites and temp
dilator substances produced by endothelium (nitric oxide)
pressure changes within the blood vessel
sympathetic activity- reduced blood flow to low activity tissues- related to stress hormone response- adrenaline produced during exercise and receptors can open or close vessels to certain tissues

Question 16

blood volume

Answer 16

primary mechanism for blood volume increases
- increase in plasma proteins mainly albumin (has an osmotic effect)
- increase in total water via alterations in kidney functions- reduced urine output and increased water retention

Question 17

blood volume changes

Answer 17

cross sectional study showed higher blood volume in trained athletes
longitudinal- early changes= plasma volume increases (10 days) then RBC count increaeses (over a few months)
HB conc and haemotocrit remain more or less then same, however absolute plasma voliume and RBC number increases

Question 18

concentric vs ecentric hypertrophy

Answer 18

concentric- occurs in power/reisstance athletes
due to increase in pressure, chamber size is same/reduced, wall thickness is sig increased
increased afterload

eccentric- occurs in endurance atheltes
due to increase in volume, chamber size is larger, wall thickness is same/small increase
increased preload