CPX panel 1 Flashcards
What is VO2 peak?
highest VO2 during an increasing work rate exercise test
What is the normal VO2 work rate relationship?
increase in 10ml/min/W
What is VO2 max?
VO2 fails to increase further despite an increase in the work rate
How do you distinguish between max and peak VO2?
max tolerable work rate results in flattening of the VO2 work rate slope = VO2 max
VO2 does not slow its rate of rise with increasing work rate, but the subject has reached its max tolerable work rate = peak VO2
What are the four characteristics of a ramp testing protocol?
- The test starts at a relatively low work rate
- VO2 max/peak can be determined in an exercise test that lasts 8-12 min
- The subject is stressed for only a few minutes at relatively high work rates
- VO2 work rate relationship can be determined if ergometry work rate can be measured (cycle)
What does the VO2 work rate relationship describe?
how much O2 is utilized by the exercising subject in relation to the quantity of external work
Why are respiration variables important to graph VO2?
gives valuable information on the coupling of external to internal respiration, which is the responsibility of the CV system
*generation of ATP
What is the VO2 response to a continuous ramp pattern exercise test (1 min duration)?
smooth increase in VO2
advantages in the ease with which the patient perceives the addition of work rate during testing
What is the VO2 response to a 2-3 min step pattern exercise test?
results in relatively abrupt changes in work rate, and the increase in VO2 at each interval is a step pattern
may cause premature fatigue
Why do steps at 1 minute give show a steady rise in VO2?
the time constant for VO2 work intensities below the AT is 35-45 sec
What is the O2 deficit?
difference between requires O2 consumption and actual O2 used
*smaller in more fit individuals
Why are big steps in ramp protocol not good for exercise testing?
becomes hard to determine what is rate limiting
VO2 is not able to adjust
test becomes how quickly can you generate ATP
What is the effect of body weight on the VO2 work rate relationship?
displaced upward 5.8 ml/min/kg of body weight during unloaded cycling at 60 rpm
*parallels normal weight
Why do obese individuals require increased VO2 to do a given amount of external work?
added VO2 cost to move limbs or the entire body
Why is a predictable adjustment not possible for body weight for a treadmill exercise?
varying center of gravity as the angle of the 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 to support balance
* makes it difficult to predict power output
What does the slope of the VO2 as a function of work rate measure?
aerobic work efficiency
What effect do athletes have on the VO2 workrate relationship?
may have slightly higher
cyclist demonstrates a slop of 11.5 ml O2/min/W
When does VCO2 increase faster than VO2?
above the AT even when the rate of VO2 increase is reduced
What does a deflection in the VO2 data represent?
ischemia and possible chest pain
due to cardiac function likely impaired squeeze function and low SV
How do you know if an exercise test had good effort?
VCO2 is greater the VO2
RER > 1.1 1
How do you know if an exercise test is abnormal (exercise limited/intolerant)?
predicted VO2 was not reaches
