LESSON 20 - what is VO2 max ? Flashcards
what is VO2 max ?
is when a plateau is reached (maximum oxygen consumption)
define how physiological systems support an increase in VO2 (beginning from before lungs) :
- O2 uptake/inspired in the lungs
- O2 transport within the heart
- O2 utilization within the muscle
define how physiological systems support an ↑ in VO2 (beginning from the muscles) :
- O2 utilization/consumption within the muscle becomes CO2 production
- CO2 flow within the heart (transport)
- CO2 expired from the lungs
what are the two components of VO2 ?
convection and diffusion
define convection :
movement through fluids (helps O2 uptake)
what is the formula for VO2 ?
Q x a-vO2 difference
what term is used for O2 uptake ?
VO2
what term is used for flow of O2 rich blood ?
Q
what term is used for O2 extraction ?
a-vO2 difference
what is the formula for Q ?
HR x SV
what is the formula for a-vo2 difference ?
CaO2 - CvO2
what is CaO2 made up of ?
[Hb] and %SaO2
what is the formula for diffusion ?
VO2 = Dmo2 x (PO2 capillary - PO2 mitochondria)
what is the term used for O2 diffusion capacity for skeletal muscle ?
Dmo2
what is the term used for driving pressure for O2 into mitochondria
PO2 capillary - PO2 mitochondria
how many possible sites of VO2 max limitation are there ?
5
name the 5 possible sites of VO2 limitations :
- pulmonary function
- cardiac output
- O2 carrying capacity of blood
- muscle diffusion
- skeletal muscles metabolic factors
define pulmonary function :
atmosphere uptake within the lungs
define cardiac output :
hearts ability to pump more blood
define O2 carrying capacity of blood :
- blood itself (blood volume & hemoglobin)
define muscle diffusion :
- SA for gas exchange
- driving pressure
- determine diffusive capabilities
define muscle metabolic factors :
muscles themselves
does reaching a maximal limit of ventilation determine VO2 max ?
reaching the maximal limit of ventilation alone does not determine VO2 max
in regards to pulmonary diffusion (%SaO2) does the ability of lungs to transport inspired O2 from alveoli to pulmonary capillaries limit VO2 max ?
yes (you need good perfusion ability)
do we hit a higher or lower VO2 max when we don’t desaturate ?
we hit a higher VO2 max
TRUE OR FALSE
pulmonary diffusion is limiting capacity ?
TRUE
when we have a greater resistance do we have a higher or lower alveolar ventilation ?
lower
TRUE OR FALSE
the following are all associated with each other ?
- low O2
- ↑ in VO2 max
- more diffusion to saturate
FALSE
- high O2
- ↑ in VO2
more diffusion to saturate
in regards to cardiac output ; does the heart’s ability to raise cardiac output limit VO2 max ?
yes, the ability of the heart to increase cardiac output is a crucial factor in determining an individual’s VO2 max.
FILL IN THE BLANK
“if the heart could pump more blood per minute, VO2 max would _________ ! “
increase
is cardiac output a limiting factor for VO2 max ?
yes
what is the formula for Q ?
Q = HR x SV
in regard to O2 carrying capacity of blood ([Hb]) ; does the amount of O2 that we carry in the blood determine VO2 max ?
yes, the O2-carrying capacity of the blood, often represented by the concentration of hemoglobin ([Hb]), is a significant factor that influences an individual’s VO2 max.
what is hemoglobin ?
the protein in RBC that binds to O2 in the lungs and transports it to the tissues, where it is released to support cellular respiration
TRUE OR FALSE
↑ [Hb] = ↑VO2 max
↓ [Hb] = ↓VO2 max
TRUE
how many muscle diffusion capacity factors are there ?
3
what are the three muscle diffusion capacity factors ?
- distance between capillary and mitochondria
- contact area
- pressure gradient b/w capillary and mitochondria
is mitochondria pressure usually high or low ?
low
what is a myocyte ?
a muscle cell
what do the three muscle diffusion capacity factors do ?
improve ability to diffuse oxygen n
define the muscle diffusion capacity factor “distance between capillary and mitochondria” :
↓ distance = ↑a-vO2 difference
define the muscle diffusion capacity factor “contact area” :
↑ surface area = ↑a-vO2 difference
define the muscle diffusion capacity factor “pressure gradient b/w capillary and mitochondria” :
↑ capillary pressure = ↑a-vO2 difference
in regards to muscle diffusing capacity (↑a-vO2 difference) ; is there a limit to the amount of O2 that we can extract from arterial blood ?
yes, there is a limit to the amount of oxygen that can be extracted from arterial blood by the muscles, and this limit is often referred to as the arteriovenous oxygen difference (a-vO2 difference).
FILL IN THE BLANK
muscle venous blood contains a fair amount of O2 even at VO2 max… O2 saturation = ___ %
15 % (not all O2 has been extracted)
is arterial content blood a limiting factor ?
no - arterial content blood isn’t a limiting factor
when at a further up altitude what happens to the pressure gradient for diffusion ?
lower pressure gradient for diffusion
when we see a ↓driving pressure what does this mean for VO2 max ?
↓ VO2 max
what does hypoxic mean ?
a state in which oxygen is not available in sufficient amounts at the tissue level to maintain adequate homeostasis
can muscle diffusion capacity limit VO2 max ?
muscle diffusion capacity CAN sometimes limit VO2 max
when we see lower hypoxia what does this mean for delta P and VO2 max ?
lower hypoxia =
- reduction in delta P
- ↓ VO2 max
in regards to skeletal muscle metabolic factors ; is there a maximal ability of the muscle to utilize O2 for ATP resynthesis ?
yes, there is a limit to the maximal ability of skeletal muscles to utilize oxygen for ATP resynthesis during aerobic metabolism.
name some factors related to the muscle’s metabolic processes and cellular machinery :
- mitochondrial capacity
- oxygen diffusion
- enzyme activity
- substrate availability
discuss VO2 max related to mitochondrial volume :
- oxidative phosphorylation needs mitochondria
- more mitochondria = more ability to use oxygen
- type 2 more
discuss VO2 max of whole muscle vs a piece of that muscle :
- skeletal muscle utilization is limiting their ability to increase their VO2 max
TRUE OR FALSE
in regards to what limits VO2 max; it depends on the person, their environment, and the type of exercise that they’re doing …
TRUE
