Ex Phys: Cardiovascular System-Acute Responses to Exercise

variables involved in acute responses to exercise

heart rate, stroke volume, and cardiac output all increase

-blood pressure (increase systolic, diastolic stays the same) and blood flow change

resting heart rate

-usually between 60-80 bpm, but can be 28-100 bpm

-tends to decrease with age and with increased cardiovascular fitness

-affected by altitude and temperature

maximum heart rate

-highest HR one can achieve in an all-out effort to the point of exhaustion

-remains constant day to day, decreases with age

-estimated by age-220

heart rate acute response to exercise

continues increasing with exercise intensity until plateau

steady state heart rate

-heart rate plateau during constant rate of submaximal work

-optimal for meeting circulatory demands at that rate of work

-the lower the steady state heart rate, the more efficient the heart

stroke volume acute response

determinant of cardiorespiratory endurance capacity at maximal rates of work

-increases with increased work rate up to intensities 40-60% maximum

-may continue to increase up through max exercise intensity for trained individuals

-can depend on body position during exercise

graph stroke volume acute response and chronic adaptation

check in journal

why does SV increase during exercise?

-increased EDV

-decreased MAP

-increased cardiac contractility

cardiac output

resting value about 5.0 L/min

-increases directly with increased exercise intensity, 20-40 L/min

-increase varies with size and conditioning

-when exercise exceeds 40-60%, heart rate contributes to increase the most (trained both contribute)

graph cardiac output acute responses and chronic adaptations

check in journal

distribution of blood flow acute response

skeletal muscles take 88% of blood during maximum exercise, about 12% other organs

-brain gets the same amount of blood in absolute terms

-heart increases slightly in absolute terms

cardiovascular drift

gradual decrease in stroke volume and systemic and pulmonary arterial pressures and an increase in HR

-with prolonged steady state exercise or hot environment

graph cardiovascular drift

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why does cardiovascular drift occur?

-fluid taken from plasma in vascular compartment

-decreased blood volume, decrease venous return, decrease EDV, and decrease stroke volume

-increase HR to maintain CO

blood pressure acute response- cardiovascular endurance exercise

systolic blood pressure increases in direct proportion to increased exercise intensity

-diastolic blood pressure changes little, if at all

blood pressure acute response- resistance exercise

-BP response as high as 480/350 mmHg

-drop in blood pressure after the valsalva manuever

graph systolic and diastolic acute responses to exercise

check in journal

blood plasma volume acute response

-reduced with onset of exercise (goes to interstitial fluid space)

-more if lost through sweat

-excessive loss can impair performance

-reduction in blood plasma volume results in hemoconcentration (increase red blood cell concentration)