11.3 Flashcards by Kiera Joy

panel 1 gives great insight into

performance of CV function

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panel 1

VO2 and VCO2 versus time and work rate

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what is the diagonal line

slope showing predicted rate of increase in O2 for the work rate increase

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interprets if a patient is

limited in exercise performance because the plot gives a global assessment of exercise performance and the presence of exercise limitation

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time course of Vo2 following onset of exercise is shown

for progressively higher work rates

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for work rate 1

the vo2 asymptote is below VO2 max

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work rate 2 reaches

a vo2 that is the same as the higher vo2 reached by work rates 3 and 4

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because the vo2 is the same for work rates 2,3, and 4

this identifies vo2 max for the form of exercise studied

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the max vo2 may be determined in a progressively increasing exercise test by

observing that vo2 fails to increase normally relative to the increase in work rate (10ml/min/W) just before the subject fatigues

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flattening of the vo2 work rate relationship, as peak vo2 is approached

is often not seen in progressively increasing exercise tests

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the highest vo2 is called

peak vo2

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peak vo2

used to describe the highest vo2 achieved in an increasing work-rate test

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the highest vo2 may also be regarded as

maximal vo2

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when is it regarded as maximal vo2

when it fails to increase normally over the last 60 secs of exercise before the subject stops exercise because of fatigue - that is vo2 fails to increase further despite an increase in work rate

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peak vo2 does not satisfy definition of maximal vo2 determined from

repeated constant work rate tests, it is usually equal to the actual vo2 max in normal subjects

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what is classic reason for termination

muscles give out before CV system
legs too heavy, hurting, tired

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when testing someone with CV disease it is uncommon to se

a plateau or peak vo2

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what is the subject’s maximal vo2 or VO2 max

when the subject maximum tolerable work rate results in a flattening of the vo2-work rate slope

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when do you know its subject’s peak (or maximum) vo2 during the test

when the vo2 does not slow its rate of rise with increasing work rate, but the subject has reached their max tolerable work rate

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ramp testing has

progressive increases in work rate

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how does ramp test start

relatively low work rate, so that it does not require abrupt application of great muscel force or a sudden, large cardiorespiratory stress

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the vo2 max or peak vo2 can be determined from an exercise test in which

the period of increasing work rate lasts only 8 to 12 minutes

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during progressive exercise test the subject is stressed

for only a few minutes at relatively high work rates

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the vo2 work rate relationship can be determined if

the ergometry work rate can be measured, such as for the cycle

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exercise test is testing

max oxidative phosphorylation rate of muscle

why does muscle stop contracting

no longer enough O2, no atp

although vo2 measurements are made from respired gas measured at the mouth, the increase in vo2 reflects

O2 utilization by the muscle cells performing the work of exercise

the vo2- work rate relationship describes

how much o2 is utilized by the exercising subject in relation to the quantity of external work performed

what valuable info does graph of vo2 and work rate as a function of time give

info concerning the coupling of external and internal (cellular) respiration

measure the ability of vo2 to track

the increase in work rate

coupling of external respiration to cellular respiration is

responsibility of the cardiovascular system

disease of some component of the CV system will result in

an abnormal pattern of gas exchange for increasing work-rate exercise

if slope less then 10 ml/min/W

red flag, some CV disease

for healthy subjects when does vo2 increasing smoothly

with cycle ergometer work rate increased in a continuous ramp pattern or in equal steps of 1 minute duration

continuous ramp pattern or equal steps of 1 minn duration protocol has advantages

ease with which the pateient perceives the addition of work rate during testing

increasing work rate in 2 or 3 minute steps results in

relatively large abrupt changes in work rate, and the increase in vo2 at each interval is a step pattern

why is steps at 1 minute increments give smooth increase in vo2

Because the time constant for vo2 at work intensities below the AT is 35 to 45 seconds in healthy subjects 35-45 secs for VO2 to adapt to next stage

testing done in stair way fashion but

body doesnt adapt in stairway fashion

adjustment to exercise occurs in

non linear fashion workload in squareway fashion

workload does not match what

body can do

work rate will have

lag to adjust to new workload

what must you makeup to get from 50w to 100W

o2 deficit

what determines O2 deficit

for more fit, faster VO2 increase smaller o2 deficit (required o2 consumption for workload diff from actual o2 consump.)

if doing step test with big changes, really testing

vo2 adjustments whereas slow ramp protocol, smooth linear response straight line vo2

for step if jump too big may

prematurely fatigue

3 minute step protocol is more

jumpy not linear response

the normal change in vo2/change in work rate is equal to

10ml/min/W

for 3 min step increases in work rate, the step appearance in vo2 is damped at higher work intensity because

of the progressive slowing of vo2 kinetics as the subject approaches vo2 max

the loss of the step change in vo2 depends

on fitness (question of how quickly can generate atp)

the position of the vo2 work rate relationship depends on

body weight

obese subjects require

increase vo2 to do a given amount of external work

why do obese subjects require increased vo2

due to added vo2 cost to move the limbs during cycling ergometry and the cost of moving the entire body during treadmill exercise

for obese individual the vo2 was found to be displace upward by approximately

5.8 ml/min/kg of body weight during unloaded cycling at 60 rpm

although upwardly displace, the work rate relationship in obesity parallels

that of the normal weight subject during cycle ergometry

for overweight individuals the slope

stays same but adjusted upward for any given work rate absolute vo2 higher

for treadmill exercise, predictable adjustment for BW is not possible because of complex mechanical factors such as:

- varying center of gravity as the angle of treadmill is changed - variable length of the stride as the speed and grade are altered - tendency of the subject to hold on to stationary objects for support or balance during test

variables for treadmill exercise make it dificult to

estimate the subject's actual power output during treadmill ergometry

to avoid the temptation of holding on to the treadmill railing for balance, advise subjects to

rest the back of the hands on the treadmill railing

why is the slope of o2 as function of work rate important

because it measures the aerobic work efficiency

higher slop in trained athletes suggests

athletes may have a slightly higher change in vo2/change in work rate than non-athletes

people with lower than 10 slope

CV disease

the data from the left of the 0 are

from the rest period

zero work rate is

unloaded cycling

the period of increasing work rate starts at

the left vertical dashed line and ends at the right vertical dashed line

the diagonal line between the vertical dashed lines is

the normal rate of rise for vo2 against work rate with a slope of 10ml/min/W

the predicted peak o2 is shown

in upper left of each panel

above peak o2 is

age and sex of patient

predicted vo2 is

what should their vo2 be for their age and sex

the change in vo2/change in WR are commonly abnormal in

patients with cv disease, with the pattern varying with the defect

the VCO increases faster than the vo2 above the AT

even when rate of vo2 is reduced

what does panel 1 tell us

if person has normal vo2 peak work rate did person have normal exercise test was it good effort what is peak power output

how to tell if good effort test

if vco2 higher than vo2 if RER which is vco2/vo2 is over 1.1

how to tell if abnormal test

vo2 lower than predicted ex) didnt reach normal, if not parallel, deflection at end, shallow

if vo2 not what it is supposed to be it is indication of

cv disease

if not normal exercise test

exercise intolerant

when can tell approximately where anaerobic threshold occurs

where vco2 rises above vo2

if vo2 drops at end

shows where ischemia occurred exercise intolerance