Ch 9 Reading

Question 1

where is pulse usually taken?

Answer 1

at radial or carotid artery

Question 2

what is an average resting heart rate (RHR)?

Answer 2

60-80 bpm

Question 3

in highly endurance trained athletes, resting rates are as low as _____bpm

Answer 3

28 bpm

Question 4

what is the anticipatory response?

Answer 4

increase in HR just before start of exercise

Question 5

how is the anticipatory response mediated?

Answer 5

through the release of norepinephrine from the sympathetic nervous system & epinephrine from the adrenal medulla

Question 6

how does HR increase in relation to exercise intensity?

Answer 6

HR increases directly in proportion to increase in exercise intensity

Question 7

what is maximal heart rate?

Answer 7

the highest HR value achieved in an all-out effort to the point of complete fatigue

Question 8

how is HRmax used?

Answer 8

in clinical exercise testing to prescribe exercise intensity

Question 9

what is the most commonly used equation for HRmax?

Answer 9

HRmax = 220 - age (years)

Question 10

what are some reasons why the common equation for HRmax is not the most accurate?

Answer 10

• overestimates HRmax in young individuals
• underestimates HRmax in older individuals

Question 11

what are two more accurate equations for HRmax?

Answer 11

HRmax = 208 - (0.7 * age)
HRmax = 211 - (0.64 * age)

Question 12

what is steady-state heart rate?

Answer 12

plateau of HR during exercise; optimal HR for meeting circulatory demands at that specific rate of work

Question 13

for each subsequent increase in intensity, HR will reach a new steady-state value within ___ min

Answer 13

3

Question 14

describe steady-state HR in fit vs unfit individuals

Answer 14

higher endurance: lower steady-state HR
lower endurance: higher steady-state HR

Question 15

a lower steady-state HR yields a _________ VO2max

Answer 15

higher

Question 16

what is heart rate variability?

Answer 16

measure of rhythmic changes in HR due to sympathetic-parasympathetic balance controling sinus rhythm

Question 17

how has analysis of HRV been used?

Answer 17

to evaluate the contributions of SNS and PSNS at rest and during exercise

Question 18

during exercise, does HRV increase or decrease? **

Answer 18

decrease

Question 19

after exercise, does HRV increase or decrease? what causes this?

Answer 19

increase, vagus nerve activity returns to calm the body down

Question 20

what does a power spectrum describe?

Answer 20

how much of heart rate signal occurs at each different frequency

Question 21

what does spectral analysis do?

Answer 21

separates HRV into different frequency components (slow and fast waves)

Question 22

how does exercise affect stroke volume?

Answer 22

SV increases above resting values

Question 23

what four factors is SV affected by?

Answer 23

1. volume of venous return
2. ventricular distensibility
3. ventricular contractility
4. aortic/pulmonary artery pressure

Question 24

how much can stroke volume increase from rest to maximal exercise in an upright position?

Answer 24

it can approximately double

Question 25

what are typical SV values for untrained individuals?

Answer 25

rest: 60-70mL/beat max exercise: 110-130mL beat

Question 26

what are typical SV values for trained endurance athletes?

Answer 26

rest: 80-110mL/beat max exercise: 160-200mL/beat

Question 27

how much does SV usually increase during supine exercise?

Answer 27

20-40%

Question 28

why is resting SV higher in supine?

Answer 28

gravity doesn't pool blood in the legs, so venous return is greater

Question 29

why does SV increase less during supine exercise than upright exercise?

Answer 29

SV in supine starts out high at rest already, leaving less room for more increase

Question 30

up to what percentage of VO2max does SV typically increase with exercise intensity?

Answer 30

40-60%

Question 31

why might SV continue to rise in highly trained athletes?

Answer 31

increased venous return and myocardiac strength from aerobic training

Question 32

what is the frank-starling mechanism?

Answer 32

the extra forceful contraction of a ventricle in response to a greater volume of blood

Question 33

how does contractility increase?

Answer 33

sympathetic nerve stim or circulating catecholamines

Question 34

when mean arterial blood pressure is low, what happens to SV?

Answer 34

there is less resistance to flow, so the ventricle can eject more blood, increasing the stroke volume

Question 35

what two main methods are used to measure stroke volume during exercise?

Answer 35

echocardiography (sound waves) and radionuclide techniques (tagging RBCs)

Question 36

what happens to EDV as exercise intensity gradually increases? how does this affect the SV?

Answer 36

increases; boosts SV through frank-starling mechanism

Question 37

what happens to EDV during high intensity exercise? how?

Answer 37

decreases; diastolic filling time short

Question 38

what two mechanisms increase SV during exercise?

Answer 38

frank-starling and increased contractility

Question 39

when is the frank-starling mechanism most used?

Answer 39

low intensities

Question 40

when is increased contractility most used?

Answer 40

at higher intensities

Question 41

why can stroke volume plateau or decrease at very high intensity exercise?

Answer 41

high HR shortens diastolic filling time, limiting how much blood the ventricle can fill with

Question 42

what are the three main factors that increase SV during exercise?

Answer 42

1. increased venous return 2. increased contractility 3. decreased total peripheral resistance

Question 43

what causes a decrease in total peripheral resistance (TPR)?

Answer 43

vasodilation