Transcript cardiac5.ppt

Cardiovascular
Responses to Exercise
Increased Q
Increased HR and SV
 Enhanced delivery of O2 and fuels to
active muscle and removal of CO2 and
waste

Increased Skin blood flow

Remove heat
Decreased blood flow to the
kidneys

Decreased urinary output and
maintenance of blood volume
Decreased visceral flow

Reduced GI activity
Maintenance or slight increase in
brain blood flow
Increased blood flow to coronary
arteries
Increased muscle blood flow
Maximal flow is limited by need to
maintain BP
 Active muscles will vasoconstrict if BP is
not maintained

CV regulation directed to maintain
BP

Balance between maintaining BP and need
for more blood to active tissue
Limits of CV Performance
VO2 max is best predictor of CV capacity
 Biochemical factors are better predictor of
endurance
 Q is the best predictor of VO2 max

– Q can increase by 20% from endurance
training, accounts for most of improvement of
VO2 max
CV changes with training
Improved ability to pump blood, increase
SV (↑ EDV, small incr. L ventricular mass)
 No change in ventricular volume
 ↑ SV, ↓ HR = more efficient pressure-time
relationship
 May increase VO2 max by 20%, depending
on initial fitness (endurance more)
 Submax and resting HR are lower

SV increase no more than 20% (increased
myocardial contractility)
 Slight increase in (a-v)O2, right shift in
dissociation curve
 Resting and submax. BP and MAP are
lower


Coronary blood flow decreases at rest and
submax work
– Increased SV and decreased HR = reduce
myocardial oxygen consumption
– No change in the vascularity of the heart
Skeletal muscle vasularity increases
 (decreased blood flow during submax
work)
