Lec 23 Vo2max And Exercise Thresholds Flashcards
What did A.V hill define
Maximal oxygen uptake
What did Hill define as vo2max
Even if speed is increased beyond a certain point no further increase in oxygen intake can occur
Heart, lungs, circulation, diffusion of o2 in the working muscles have attained maximal activity
Will eventually plateau
Vo2max is what kind of measure
Is a quantitatively measure of individuals capacity for aerobic ATP synthesis
What are the three ways to measure vo2max
Ramp incremental
Step incremental
Constant intensity
Normalizing by ________________ eliminates sex based differences in vo2max
Lean body mass
What happens to vo2max with age and how much per decade
Declines
8%/decade
Ventilations shows a ___________ relationship during a vo2max test
Curvilinear
Why do we perform ramp incremental tests
1) to determine exercise capacity aka vo2max
2) to identify cardiorespiratory response thresholds
What are the two methods to measure blood lactate threshold
1) measuring blood lactate
2) measuring ventilatory and gas exchange thresholds
During phase 1
What happens to o2 consumption, co2 production, ventilation, blood lactate, metabolic state
Linear increase in o2 consumption, co2 production, ventilation
Metabolic stability (Steady state)
Blood lactate and h+ are consistent
Will reach a plateau
What are the boundaries of the moderate intensity domain
Lower boundary is rest
Upper boundary is GET (LT1)
Low metabolic demand
During moderate intensity what happens to vo2
When does it occur
What happens to lactate
Reaches a steady state within 2-3 minutes
Lactate remain around resting values
How long can the moderate intensity be sustained and what is the degree of fatigue
Can sustain this intensity for a very long time and fatigue is minimal
What happens to lactate levels at moderate intensities
And why
Remain near resting levels
ATP demands are met mostly through AEROBIC metabolism (glycolysis and glycogenolysis)
Pyruvate production is equal to pyruvate oxidation so little is left over to be converted to lactate
Phase 2 heavy domain
What happens to o2 consumption, co2 production, ventilation, blood lactate, metabolic state
Linear increase in o2 consumption
Nonlinear increase in co2 production (GET)
Ventilation increase in a faster rate in relation to increased work load or vo2
Metabolic stability (steady state)
Blood lactate are consistent but at a higher level
Blood lactate production and clearance is still at equilibrium
Will eventually also plateau
What happens at GET
Co2 and h+ are buffered by BICARBONATE causing an increase in co2
Production
Activation of GLYCOLYTIC PATHWAYS which increases the rate of h+ production
When does the heavy intensity domain start what is the upper boundary
What happens to VO2 and at what time
Above GET
Upper boundary is the critical intensity of exercise aka MLSS
- the highest metabolic rate at which steady state respond of VO2 and lactate are achievable
Steady state plateau will occur around 10-15 mins
What happens to lactate in the heavy domain and why
Lactate production is greater
Due to greater metabolic demand there is an increase in the rate of pyruvate production which exceed the rate of uptake and oxidation resulting in the production of lactate
In the heavy domain are steady state still achievable and why
Although metabolic demands and lactate are elevated, steady state responses are still achieved as the physiological buffering systems are able to Minimize the metabolic disturbances
Aka bicarbonate co2 buffering system, hemoglobin, proteins, and phosphates)
Phase three
Severe domain
What happens to o2 consumption, co2 production, ventilation, blood lactate, metabolic state
Linear increase in o2 consumption
Nonlinear increase in co2 production
HYPERVENTILATION can NOT compensate the rise in H+
No metabolic stability (no steady state)
Blood lactate production exceeds the clearance
RCP AND BEYOND
Nonlinear increase in ___________ compared to co2 production
How does the body compensate for the decrease in ph
Hyperventilation _______ compensate for the rise in h+
Ventilation
Ventilation increases out of proportion to vco2
Cannot
Within phase three why is there a mismatch between ventilation and co2
h+
Severe intensity starts when
Past RCP or critical intensity
When compare to moderate and heavy domains, what is a main different is severe domain
A steady state VO2 response is not attainable
Therefore the increase in hydrogen ions and co2 production exceed the ability of the bicarbonate co2 buffering system
Faster rate of glycolysis, exceeds the ability of the mitochondria to accept the increased rate of pyruvate as well as the capacity of the system to buffer the increased h+ associate with the conversion of lactate to pyruvate
Acceleration of lactate accumulation
