Oxygen Uptake Kinetics Flashcards
Define oxygen uptake kinetics
Study of the physiological mechanisms responsible for the dynamic VO2
response to exercise & recovery
How many dynamic response phases are there?
3
What does oxygen uptake determine?
Rate of aerobic/anaerobic energy transfer
Tolerable duration of exercise
What controls/limits oxygen uptake kinetics? (2)
Rate of O2 delivery to active muscle
Ability of muscle to utilise O2
What causes the O2 deficit?
A lag in VO2
Why does the VO2 lag occur? (2)
Intrinsic inertia in cellular metabolic signals
Sluggishness of O2 delivery to mitochondria
What does the O2 deficit represent (simply)?
Difference between total VO2 and total that would be present had steady state occurred from start
Name each (3) phases of oxygen uptake kinetics:
P1: Cardio-dynamic phase
P2: Fundamental (fast) component
P3: Steady state or slow component
How long does P1 take?
Approx 15 secs
Describe P1:
Inc in VO2 reflects inc in VR
Blood coming back to lungs hasn’t had inc in O2 extraction
Describe P2:
VO2 continues to rise exponentially (quicker steady state is reached = less o2 deficit)
Describe P3 (steady state) :
VO2 achieves steady state, CO plateaus
Response amplitude is lower post training
Describe P3 (slow component) :
VO2 continues to increase, rather than plateau
Additional O2 cost drains body of fuel stores rapidly
Larger slow component = shorter exercise tolerability
When is P3 known as ‘steady state’ and when is it now as the ‘slow component’, and why?
Steady state: When exercise is below LT
Slow component: When exercise is above LT
Why: Because VO2 still increases in P3 (SLOWLY) during SLOW component
Define amplitude (in relation to o2 kinetics) :
Signifies O2 demand of the working muscle
What does time delay mean (in relation to o2 kinetics) :
Time elapsed before O2 expired reflects demand of working muscles (length of time before P2 starts
What does time constant mean (in relation to o2 kinetics) :
Time taken to reach 63% of amplitude
Speed of response
What does mean response time mean (in relation to o2 kinetics) :
Overall kinetic response
Time taken to reach 63% of VO2 increase above baseline
What is priming? (in relation to o2 kinetics)
Any activity that takes place before the main bout of exercise
Why is priming done?
To try and modify VO2 kinetics response
How is priming done?
Exercise intensity has to exceed LT to modify VO2 kinetics response
What effect does priming have on O2 deficit?
Priming decreases O2 deficit
What is one of the major advantages of using priming?
It doesn’t need to focus on the same specific muscles to be of benefit
What are the two overall benefits?
Speeds up the overall kinetic response
Reduces slow component phase
Explain the specifics of priming:
An exercise bout of 6 mins approx takes place
Vasodilation occurs (academia)
More nutrients can get to working muscles / shift O2 dissociation curve to the right
What was EPOC previously known as?
Oxygen debt
What does EPOC stand for and represent?
Excess post exercise oxygen consumption
Represents VO2 above what is normally consumed at rest
How long does EPOC last and what does this depend on?
Can be very short or very long or in between
Depends on intensity, duration, training status, sex
What is EPOC affected by?
Anaerobic metabolism level in previous exercise bout
(Resp, circ, horm, ionic, thermal adjustment that inc metabolism during recovery
What is the percentage split between fast and slow EPOC components?
Fast: 20%
Slow: 80%
Give some fast component roles:
Restore PCr stores
Restore myoglobin stores
Restore blood o2 stores
Restore sodium/potassium balance in nerves/muscles
Keeps blood flow and ventilation elevated
Give some slow component roles:
Glycogen resynthesis
Lactate converted to glucose
Lactate converted to pyruvate in muscle
Elevated metabolic rate (body temp)
