Cardiovascular Responses to Exercise

Increased Q Increased HR and SV Increased HR and SV Enhanced delivery of O 2 and fuels to active muscle and removal of CO 2 and waste Enhanced delivery of O 2 and fuels to active muscle and removal of CO 2 and waste

Increased Skin blood flow Remove heat Remove heat

Decreased blood flow to the kidneys Decreased urinary output and maintenance of blood volume Decreased urinary output and maintenance of blood volume

Decreased visceral flow Reduced GI activity 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 Maximal flow is limited by need to maintain BP Active muscles will vasoconstrict if BP is not maintained 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 Balance between maintaining BP and need for more blood to active tissue

Limits of CV Performance VO 2 max is best predictor of CV capacity VO 2 max is best predictor of CV capacity Biochemical factors are better predictor of endurance Biochemical factors are better predictor of endurance Q is the best predictor of VO 2 max Q is the best predictor of VO 2 max –Q can increase by 20% from endurance training, accounts for most of improvement of VO 2 max

CV changes with training Improved ability to pump blood, increase SV ( ↑ EDV, small incr. L ventricular mass) Improved ability to pump blood, increase SV ( ↑ EDV, small incr. L ventricular mass) No change in ventricular volume No change in ventricular volume ↑ SV, ↓ HR = more efficient pressure-time relationship ↑ SV, ↓ HR = more efficient pressure-time relationship May increase VO 2 max by 20%, depending on initial fitness (endurance more) May increase VO 2 max by 20%, depending on initial fitness (endurance more) Submax and resting HR are lower Submax and resting HR are lower

SV increase no more than 20% (increased myocardial contractility) SV increase no more than 20% (increased myocardial contractility) Slight increase in (a-v)O 2, right shift in dissociation curve Slight increase in (a-v)O 2, right shift in dissociation curve Resting and submax. BP and MAP are lower Resting and submax. BP and MAP are lower

Coronary blood flow decreases at rest and submax work 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 Skeletal muscle vasularity increases (decreased blood flow during submax work) (decreased blood flow during submax work)