Download Functions during exercise

Functions during exercise
stroke volume - amount of blood pumped during each
systole
– 33% increase during exercise
– maximal stroke volume and maximal heart rate do not always
coincide
– ? intense exercise
Cardiac output/blood pressure
amount of blood pumped by the heart each minute
HR X SV = Q
majority of increase in Q is due to increased HR, small
increase in SV
blood pressure varies
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HR
blood volume
ventricular contraction
resistance of blood flow
normal systemic blood pressure in horse
– 135/95 to 155/110
– pulmonary blood pressure much lower
• less force of contraction, less resistance to flow
Total Blood Volume
critical index of a horses fitness
factors contributing to total blood volume and hemoglobin
– breed, age, bodyweight, training & sex
training
– sprint trained animals have lower Hg levels and PCV than
endurance trained animals
– ? - more aerobic work stimulates more production of RBC by bone
marrow
Blood Circulation
onset of exercise
– some plasma diffuses from blood to tissue
– blood becomes more viscous
• high PCV
– O2 carrying capacity increases due to increased
% of RBC per unit of blood
– shift of blood from other body parts to exercising muscle tissue
– *15% to 85% to muscle
– *assists in thermoregulation
– *diaphragm
Effects of Conditioning
cardiovascular changes occur quite rapidly (2 months)
resting HR - no change
maximal HR - no change
heart rate lower following conditioning to do same
workload as unconditioned
HR returns to resting value faster with conditioning
endurance conditioning increases plasma volume 20% and
hemoglobin concentration 34% (increased SV)
sprint conditioning - greater increases in PCV, RBC, and
hemoglobin then endurance conditioning (resting)