exercise intensity domains Flashcards
what is the gold standard protocol for VO2 max testing and exercise thresholds
ramp incremental test (RIT)
what is the relationship between O2 measured from the mouth and PO
increase linearly
what is mean response time (MRT)
delay in VO2 increase in relation to PO at the beginning of RIT
- PO increases while VO2 is stable for a few seconds
what causes MRT
transit delay in physiological repsonses that need to occur at the beginning of exercise to meet muscle VO2 demand
- takes time for the level of O2 to go down in the musce and for the resp system to respond (transit time - values only measured at the mouth)
how to account for MRT when prescribing exercise
PO difference produced by MRT should be subtracted from the ramp PO
(otherwise exercise intensity will be underestimated)
which factors need to be considered in the moderate, heavy, and severe domains
moderate = MRT
heavy and severe = MRT and slow component
what is the slow component
VO2 gradually goes up even at constant PO (drift in O2 uptake)
- as intensity increases, differences between VO2 and PO increases (increases dissociation)
when does dissociation of VO2 in relation to RIT happen (slow component)
above GET - highest after RCP
(no slow component in moderate domain)
what are the differences in constant load and RIT
higher VO2 in constant load/step
need to correct for slow component in RIT
what are the reasons for the slow component (VO2 dissociation)
80% oxygen uptake in muscle during exercise
increased ATP turnover in muscle fibres
why is there increased ATP turnover in muscle fibres
increased metabolic cost of fatiguing fibres
- tired muscle units = inefficient
- greater VO2 needed
- more energy needed for ion pumping
recruitment for more type II muscle fibres
- type II = less efficient than type I
- replacing fatigued type I fibres
who has more or less slow component and why
women = less slow component
- have more type I muscle fibres therefore delayed recruitment of type II fibres
untrained = large slow component
- early recruitment of type II fibres
how much dissociation of O2 uptake happens in moderate intensity domain
no dissociation
how much dissociation of O2 uptake happens in heavy intensity domain
VO2 takes longer to stabilise and reaches values that are greater than predicted
- won’t reach VO2 max due to slow component
how much dissociation of O2 uptake happens in severe intensity domain
VO2 gradually increases to VO2 max due to VO2 dissociation (drifts up)
only domain where this happens
how much dissociation of O2 uptake happens in extreme intensity domain
- exhaustion occurs before VO2 max reached
- all exponential - no plateau in VO2
why are thresholds important
prescribe exercise accurately
- same relative intesnity
- put individuals in the correct domain
predicts exercise performance
- determine the feasibility of a given task
- can predict how long people can go
what is the exercise tolerance across the different domains
severe = seconds-45 mins
heavy = 45 mins-2 hours
moderate = >2 hours
what is the variance in GET
40-80% of VO2max
typical = 60-65%
low end = untrained
high end = trained
what is the variance in RCP
65-95% of VO2max
typical = 80%
low end = untrained
high end = highly trained
can you shift the ratio between GET and RCP
yes
ex: 400m runner = high GET but low RCP % of VO2max
what is the effect of slope of RIT on PO
at GET = very close (very small PO difference between slopes)
at RCP = large PO difference
way higher in larger slope
longer time = higher fatigue, can sustain less PO
what is the effect of slope of RIT on VO2
no effect
same VO2 response at each threshold regardless of slope
what is critical power
max rate of work that a muscle/muscle group can keep up with for a very long time without fatigue
greatest metabolic rate that results in only oxidative energy production
what can critical power be used for
find RCP threshold without metabolic cart or lactate measures
- severe vs heavy domain
how to find critical power
needs multiple sessiosn ot task failure
session 1 = very high intensity to failure
PO lowers with each session
can predict from PO curve
what is W’
shape of hyperbolic curve
- area under the curve of the power v time graph (above critical power line)
amount of work that can be performed above critical power
what does W’ predict
time to exhaustion in the severe intensity domain
what is W’ correlated with
type II muscle fibres (above RCP)
no correlation with mito content and type I fibres
what is W’ a measure of
exercise tolerance for intensities dependent on anaerobic metabolism (above critical power)
what is critical power correlated with
elevates with increasing mito content and type I fibres
what does the critical intensity of exercise separate
heavy and severe domain
above = unstable (exponential increase in VO2 and blood lactate)
below = metabolically stable
how to find critical intensity
MLSS and CP
