7. Exercise Physiology Flashcards
1
Q
How do you index VO2 (maximal oxygen uptake) in exercise testing?
A
Body weight in kg
2
Q
What 2 things is a higher max VO2 related to?
A
- Mass of muscle used (more muscle groups used = higher VO2 max)
- Amount of exercise done
3
Q
What type of exercise will have the highest maximal O2 uptake?
A
Treadmill ergometer
4
Q
What cardiac index has the smallest increase with exercise when measured in the supine position?
A
Stroke volume
5
Q
What 2 things is stroke volume dependent on?
A
- LVEDV
2. EF
6
Q
What happens to stroke volume in the supine position?
A
Increases due to increased volume return to heart (increased EDV)
7
Q
What happens to stroke volume in the supine position with exercise?
A
SV already increased from baseline due to supine position… volume needed to reach max SV is small and limited
8
Q
How does stroke volume change during exercise?
A
Increases early in exercise and little change thereafter
9
Q
What happens to CO during exercise?
A
Increases
10
Q
What happens to HR during exercise?
A
Increases
11
Q
What happens to EF during exercise?
A
Increases
12
Q
What happens to total peripheral resistance during exercise?
A
Decreases
13
Q
Why does total peripheral resistance decrease during exercise?
A
Decreased skeletal muscle vascular resistance allowing more blood flow to muscles
14
Q
What happens to CVP during exercise?
A
No change
15
Q
Why doesn’t CVP change during exercise?
A
Compensatory mechanisms of skeletal muscle pump and respiratory pump - Promotes increased venous return, so CVP doesn’t need to increase
16
Q
Constant muscle length (no change) against a force or tension?
A
Isometric exercise
17
Q
Examples of isometric exercise?
A
- Holding a weight in a fixed position
- Pushing against a door frame
- Hangrip
18
Q
What happens to SBP/DBP during isometric exercise?
A
Both increase significantly
19
Q
What happens to SBP/DBP during isotonic exercise?
A
- SBP increases
2. DBP remains relatively unchanged (within 10mmHg of resting DBP)
20
Q
What is the increase in SBP during isotonic exercise attributable to?
A
Increased CO despite reduction in total systemic resistance
21
Q
What is the relationship between HR and VO2 max?
A
Linear until max workload achieved
22
Q
Typical max HR for an adolescent?
A
195-215
23
Q
Normal VO2 max?
A
35-45
24
Q
Accepted max HR for patients 5-20 years?
A
195-215bpm
25
Accepted max HR for patients >20 years?
210 - (0.65 * age)
26
Difference in maximal RR, tidal volume and minute ventilator at peak exercise as child ages?
1. RR decreases
2. TV increases
3. MVe increases
27
How does minute ventilation in exercise increase?
1. Increase in ventilation frequency
| 2. Increase in tidal volume
28
Change in SV, resting HR, max HR and CO with improved fitness?
1. Increased SV
2. Decreased resting HR
3. No change to max HR
4. Increase CO
29
With conditioning, what causes decrease in resting HR?
1. Increased SV
| 2. Increased vagal tone at rest
30
True or False: In the same subject, a higher VO2 mx can be achieved with treadmill testing compared to cycle testing?
True
-More muscle groups used when exercising on a treadmill versus cycle
31
What is the standard unit of work?
Joule
32
What is VO2 max?
VO2 reached when it plateaus
33
Do most centers use isotonic or isometric exercise-testing protocols?
Isotonic
34
What conditions are a contraindication for exercise testing?
1. Severe pulmonary HTN
2. Acute MI (fragile myocardial tissue)
3. Acute rheumatic fever (fragile myocardial tissue)
35
True or False: History of MI or rheumatic fever are contraindications to exercise testing?
False
-Can't test in acute period, but history of this should have testing to assess fatigue or exercise intolerance
36
What happens to resting HR, max HR and VO2 max for someone who is deconditioned?
1. Resting HR increases
2. VO2 max decreases
3. Max HR doesn't change
37
What does is mean is someone doesn't achieve max HR during exercise testing?
1. Submaximal effort
| 2. Patient has chronotropic insufficiency
38
During incremental exercise, what is ventilator anaerobic threshold reflective of?
Onset of anaerobic metabolism
39
When does ventilator anaerobic threshold occur during exercise?
At point where there is disproportionate increase in minute ventilation relative to O2 uptake
40
What does the disproportionate increase in minute ventilation relative to O2 uptake result in?
Increased expiration of mixed oxygen concentration
-Can see disproportionate increase in lactate in adults
41
When does decompensated acidosis occur during exercise?
After the ventilator anaerobic threshold has occurred
42
A cyanotic patient at peak exercise will have a higher ___ compared to an aycanotic patient?
Ventilator equivalent for oxygen
43
What is minute ventilation divided by oxygen uptake?
Ventilator equivalent for oxygen
44
What is a major determinant of increased ventilator equivalent for oxygen in cyanotic patients?
Presence of large R-L shunting
45
What happens to minute ventilation for cyanotic patients at peak exercise?
Increase minute ventilation disproportionately to oxygen uptake
-Results in a higher ventilator equivalent for oxygen than acyanotic patients
46
True or False: SpO2 and VO2max are lower in cyanotic patients that acyanotic patients?
True
47
Which exercise protocol involves small, frequent increases of workload?
Bruce and "modified" bruce
48
Which protocol involves cycle ergometry with large increments of workload?
James
49
Which treadmill protocol uses a constantly increasing workload?
Ramp treadmill protocol
50
What is a disadvantage of the ramp treadmill protocol?
Doesn't allow assessment of steady-state exercise due to constant change in workload
51
What happens to Ve/VO2 in early exercise?
Decreases
52
Why does Ve/VO2 decrease in early exercise?
Pulmonary blood flow increases and resting V/Q mismatch is reduced- More uniform perfusion of lungs and ventilation
53
What happens to Ve/VO2 when the ventilator anaerobic threshold is reached?
Decreases
54
What happens to minute ventilation, respiratory rate and tidal volume with increased work?
1. Ve increases
2. RR increases
3. TV increases
55
What happens with age to minute ventilation, max respiratory rate and tidal volume with increased work?
1. Ve increases
2. Max RR decreases
3. TV increases
56
What causes normal patients to terminate exercise?
CO can no longer increase
-There is typically still ventilator reserve available
57
What is acetylene-helium exercise testing dependent upon?
Even distribution of inspired gas in the lung
58
What technique is used to measure CO indirectly by measuring effective pulmonary blood flow in the absence of significant intracardiac shunts?
Acetylene-helium rebreating
59
What exercise testing technique isn't reliable for CO measurement in patients with lung disease that involves mismatching of ventilation and perfusion?
Acetylene-helium
60
Sphygmomanometer cuff should have a bladder length that covers what % of the circumference of the upper arm and what % width of the upper arm?
80% circumference
| 40% width
61
What happens to VO2 max and Ve with improved fitness?
Both increase
62
Does ability to achieve max HR and BP limit with deconditioning?
No
63
When is max voluntary ventilation obtained?
At rest
64
What is max voluntary ventilation dependent on?
Patient effort
-Use cautiously when suggesting pulmonary limitation
65
What value is max voluntary ventilation?
35-40x patient effort
66
At the point of exercise termination in a normal patient, Ve is what % of MVV?
60-70%
67
In a patient with lung disease and pulmonary limitation, the achieved Ve is what % of MVV?
Can be >70%
-Tap into ventilator reserve
68
What is a more accurate method of assessing pulmonary limitation to exercise besides MVV?
Tidal flow-volume loops
69
What testing has the advantage of assessing vocal cord dysfunction?
Tidal flow-volume loops
70
True or False: African American children have a higher blood pressure response to exercise when compared to Caucasian children?
True
71
True or False: Size of a child has no impact on blood pressure response to exercise
False- Larger sized children have a higher blood pressure response when compared to smaller sized children
72
Which gender (if similar sized patient) has a higher blood pressure response to exercise?
Boys
73
How does CO increase during exercise?
Increases in HR and SV
74
What happens to end-systolic volume during exercise?
Decreases
75
What happens to diastolic BP during isotonic exercise?
Stable (change <10mmHg)
76
What happens to DBP during isometric exercise?
Increases
77
BP increases during exercise predominantly occur by what?
Increased CO
78
What happens to total systemic resistance during exercise?
Decreases
79
What test is used to measure CO indirectly by measuring effective pulmonary blood flow in the absence of significant intracardiac shunts?
Acetylene-helium rebreathing technique
80
What is the acetylene-helium rebreathing technique dependent on?
Even distribution of the inspired gas throughout the lung
81
What types of patients is acetylene-helium rebreathing as a measure of CO not reliable in?
1. Lung disease with VQ mismatch
| 2. Significant intracardiac or intrapulmonary shunts
82
During exercise stress testing, what direct measurement can be determined by using acetylene-helium rebreathing technique?
Effective pulmonary blood flow
83
True or False: Acetylene-helium rebreathing is well tolerated by children?
True (non-invasive technique)
84
What does the acetylene-helium rebreathing estimate?
CO (it directly measures effective pulmonary blood flow)
85
How does acetylene-helium rebreathing work?
- Acetylene diffuses from the alveolus into the pulmonary capillary blood
- Acetylene concentration declines relative to volume of effective pulmonary blood flow
86
In a healthy, normal child, what organ system is most commonly responsible for limiting maximal achievable workload?
Cardiovascular
87
When is maximum CO achieved?
When max HR limits ventricular filling during diastole and in turn stroke volume?
88
How long can a well-fit patient exercise at their max HR?
1-2 minutes
89
True or False: The pulmonary system in a normal, healthy child won't limit exercise capacity
True
90
Minute ventilation and work have a linear relationship until what is achieved?
Ventilator anaerobic threshold
91
What happens to minute ventilation and work at the ventilator anaerobic threshold?
Disproportionate increase in Ve relative to VO2
92
At the point of exhaustion, Ve is what % of the maximum ventilation volume?
60-70%
93
What is the equation for work?
Work = Force * Distance
94
What is the force needed to move a mass a given distance?
Work
95
What is the unit for work?
Newton-meter or joule (J)
96
What is the equation for Force?
Force = Mass * Acceleration
97
What is the equation for Power?
Work performed per unit of time
98
For patients ages 5-20, what is the estimated HR max?
195-215bpm
99
What happens to the max HR for patients >20?
It decreases with increasing age
100
Equation for Max HR?
Max HR: 210 - (0.65*age)
101
Why does max HR decrease with age?
Unclear... may be due to fibrosis and scarring of the SA node
102
Describe change in SV with exercise?
Increases early, then little change thereafter
*HR continues to increase which accounts for increasing CO
103
What happens to total SVR with exercise?
Decreases
104
For isotonic exercise, what happens to SBP and DBP?
SBP increases, DBP remains unchanged
105
For isometric exercise, what happens to SBP and DBP?
Both rise
106
What is VO2 max dependent on?
```
Age
Sex
Ethnicity
Hgb level
Type of work
```
107
What happens to Max VO2 with increasing age?
Increases
108
Describe relationship between gender for VO2 max
Before puberty: Same
| After puberty: Males have higher VO2 max
109
What happens to VO2 max in patients with anemia?
Lower
110
What type of work results in a higher VO2 max?
Highest: Treadmill ergometry
Cycle ergometry
Arm crank ergometry
Lowest: Hand grip ergometry
*More muscle groups involved = Higher VO2 max
111
Describe HR, SV, LVEDD and LVESD for a well-trained athlete
HR decreases
SV increases at rest and max HR
Increased LVEDD
Decreased LVESD
112
True or False: Severe AS is an absolute contraindication to exercise testing?
True
113
Describe pros/cons of treadmill v. cycle ergometry
- Neither treadmill nor cycle ergometry is superior to the other
- Treadmill allows higher VO2 max (more muscle groups during exercise)
- Most people can walk efficiently but not everyone can cycle efficiently
- Treadmill is potentially more dangerous due to potential of falling
- Treadmill with more noise and artifact
- More accurate and controlled measurement of work can be obtained with cycle
114
In aortic stenosis, what is the relationship between work performed and transaortic pressure gradient?
Total work performed has an inverse relationship with transaortic pressure gradient
115
What can exercise testing be helpful to determine in mild-mod AS?
1. Significant ST segment changes
| 2. Distinguish between chest wall pain or more concerning cause
116
True or False: Patients with more severe AS (higher transaortic gradient) have a lower increase in BP response during exercise than less severe AS patients
True
117
True or False: The lower the transaortic gradient, the more likely ST segment changes will occur
False
118
True or False: Patients with more severe AS achieve a lower VO2 max
True
119
What happens to the maximum aerobic power and ventilation relative to VO2 for unrepaired single ventricle patients?
- Reduced maximal power
| - Excessive ventilation relative to VO2
120
True or False: Unrepaired single ventricle patients have decreased total work, maximal power achieved, exercise time and maximal oxygen uptake when compared to 1st stage repaired or complete repair patients as well as normal patients
True
121
What happens to SpO2 in unrepaired and stage 1 single ventricle patients during exercise?
Significantly decrease
122
What happens to SpO2 in complete repair for single ventricle patients during exercise?
May have small decrease
*Similar to normal, healthy patients who have little to no decrease with exercise
123
When should ECGs be obtained during exercise testing?
At rest sitting, supine and standing then at each workload and peak exercise as well as each minute of recovery (1-5)
124
What kind of rhythm strip should be running during exercise testing?
- At least 3 standard surface ECG leads during the study and for 5-10 minutes after the study completed
- Should have the option of switching between various combinations of leads
125
What is important to do to limit artifact during exercise testing?
Appropriate ECG electrode and lead placement... cleansing/abrading, electrode paste, ECG lead cable securing with elastic band/knit shirt
126
True or False: BP can be difficulty to measure accurately during exercise testing?
True- especially diastolic BP
127
What happens to BP if you use an a-line during exercise testing?
Overestimate central aortic pressure due to peripheral amplification
128
Compared to an aycanotic patient, a cyanotic patient at peak exercise will exhibit higher...?
Ventilatory equivalent
129
Why do cyanotic patients have a higher ventilatory equivalent at peak exercise?
R-L shunt results in increased dead space... they over-ventilate to remove additional CO2
*Ventilation is disproportionately high relative to VO2
130
What are the 2 rebreathing techniques used most frequently to measure CO non-invasively?
1. CO2 rebreathing technique
| 2. Acetylene-Helium rebreathing technique
131
What is the CO2 rebreathing technique based on?
Fick principle CO2
132
What are 2 ways to get the arterial CO2 content needed in the CO2 rebreathing technique?
1. Directly measured from systemic arterial blood pCO2
| 2. Noninvasively using the Bohr equation
133
What is this equation?
VD/VT = (PaCO2-PeCO2)/PaCO2
Bohr equation
134
Why isn't the CO2 rebreathing technique tolerated (especially by children)?
Can cause dyspnea, unpleasant taste and transient headache
135
What are 2 areas for error of with CO2 rebreathing technique?
1. Adjust CO2 concentration for patient's size/exercise intensity
2. Take into account dead space
