W17. VO2 max and Gas Exchange Thresholds Flashcards
What is the definition of VO2 max?
Max volume of oxygen that can be measured during aerobic exercise
Why is VO2 max measured?
Good indicator for cardiorespiratory fitness
What does VO2 max represent?
The functional capacity of circulation (O2 delivery and O2 extraction)
What organisation does VO2 max criteria come from?
BASES
What is the most important BASES VO2 max criteria?
A plateau in O2 uptake (or an increase of no more than 3% / 2ml/kg/min
Essentially how do we know when we are looking at VO2 max?
If exercise intensity keeps increasing but VO2 doesn’t continue with it
When should the term VO2 peak be used instead?
If there is no plateau
What are some secondary VO2 max criteria?
RPE of 19 or 20
Subjective fatigue
Final RER of greater than 1.15
Reach within 10 beats of maximal HR
Why might there not be a plateau?
May have been discomfort or decrease in motivation
Processing method may not be able to identify a plateau
What are the main physiological determinants of VO2 max?
Maximal CO
Skeletal muscles (inc ability to extract oxygen)
O2 carrying capacity of blood
How does body size affect VO2 max?
Positive correlation between body size and VO2 max
If expressed relatively, effect of body size is reduced
How does sex affect VO2 max (and what ages do they peak)?
No difference until age 12+
Peaks for boys between 17-21, peaks for girls between 12-15
Women generally display 15-30% lower than men
How does age affect VO2 max?
Decreases by 1% per year from mid 20s unless training occurs
What sport produces the highest VO2 max scores on average?
Highest: Cross country skiing
What does GET stand for?
Gas Exchange Threshold
What is the first GET known as?
Ventilatory Threshold (VT)
What is the second GET known as?
Respiratory Compensation Point (RCP)
What test can be used to determine GET and VO2 max?
Progressive maximal test (to limit of tolerance)
Why is VT measured?
Indicates the point where blood flow of exercising muscle is no longer sufficient to meet metabolic demand
What are some of the physiological causes of VT?
First sign of bicarbonate buffering onset
What does RCP depict?
The final phase from buffering to exercise acidosis (lactic acid)
What is the period between VT and RCP called and how long does it last?
Isocapnic buffering zone
Only lasts a couple of mins
What is the period between RCP and the end of exercise called and what does it mean?
Hypocapnic hyperventilation phase
Means exercise can only be continued for a few minutes
How do you determine VT?
Using the V Slope method
Plot VO2 and VCO2 and look for where lines of best fit intersect
How do you determine RCP?
Plot VE and VCO2 and look for where lines of best fit intersect
What is the Ventilatory Equivalents method?
Most common method used in SES and can determine VT and RCP
How does the Ventilatory Equivalents method work?
VT: First point where VE/VO2 increases without increase in VE/VCO2
RCP: First point where VE/VO2 and VE/VCO2 increase together
What is the dual criterion method?
Most accurate GET method
How does the dual criterion method work?
Combines ventilatory equivalent method and end tidal gas tension method
What should you always do when checking VT and RCP (regarding methods)?
Always use more than one to double check and back up the results
