LESSON 14 - exercise thresholds Flashcards
what dose increasing lactate mean for protons ?
increasing protons
does increased lactate have an acidifying or basic effect
acidifying (increased protons (H+) = decreased pH)
what is buffering protons ?
neutralizing (keep us at that level)
what does bicarbonate do ?
compensate for that acidity
when bicarbonate combines with H what does it form ?
water and carbon dioxide
H + HCO3 produces H2O + CO2 uses what anhydrase ?
carbonic anhydrase
what keeps CO2 from accumulating and drives the carbonic anhydrase reactions towards production of CO2 and “consumption” of H+ ?
ventilation
what are the two metabolic boundaries ?
- lactate threshold (LT)
- critical intensity (CI) or maximal metabolic steady-state
describe lactate threshold :
the metabolic rate (or VO2) at which blood lactate cannot be maintained at resting levels
what types of intensity is lactate threshold ?
separates moderate from heavy intensity exercise domains
describe critical intensity or maximal metabolic steady-state :
- the highest VO2 at which a heightened lactate production in muscle may be stabilized in blood
what types of intensity is critical intensity ?
separates heavy from severe intensity exercise domains
how can we detect these boundary crossings through incremental exercise ?
by measuring gas exchange and ventilation at the mouth
dissociating bicarbonate makes what ?
CO2 & H2O
for every O2 we produce about the same rate amount of what …
CO2
if we have no change in lactate (pH remains stable) what does this mean for bicarbonate ?
no bicarbonate since no buffering is needed
is lactate and pyruvate a reversible equation ?
yes !
what is used to convert pyruvate to Lactate ?
lactate dehydrogenase
at a low production, describe lactate appearance …
rate of lactate appearance equals disappearance
below the lactate threshold (moderate) is hyperpnea or hyperventilation ?
hyperpnea (healthy amount)
do we want a lot of lactate ?
- no we do not
- we want a low concentration in cytosol to maintain equilibrium
where is lactate produced ?
in the muscle
what is lactate associated with ?
with an increase in H+ ions
above all else what is most important to maintain ?
H+ (bicarbonate plays a role in this)
we don’t want too much pyruvate, but why do we need pyruvate ?
to support ATP rate demand
what does stopping pyruvate inhibit ?
glycolysis (dont want that)
when is steady state achieved ?
when lactate is stable
what organ replenishes bicarbonate ?
kidneys
moderate and heavy states are both examples of hyperpnea or hyperventilation ?
hyperpnea
what does it mean when lactate is elevates and unstable ?
- high production
- rate of lactate appearance exceeds clearance
severe states is hyperpnea or hyperventilation ?
hyperventilation
what are the two metabolic thresholds ?
GET/VT1 and RCP/VT2
describe GET/VT1:
- the VO2 at the onset of bicarbonate buffering where VCO2 and VE begin to increase at a greater rate than VO2
- ≈ LT
what does GET/VT1 seperate ?
moderate from heavy intensity exercise domains
describe RCP/VT2 :
- the VO2 at which bicarbonate buffering cannot prevent acidosis and hyperventilation ensues to compensate
- ≈ CI
what does RCP/VT2 separate ?
heavy from severe intensity exercise domains
is GET/VT1 hyperpnea or hyperventilation ?
hyperpnea
is RCP/VT2 hyperpnea or hyperventilation ?
hyperventilation
what does GET stand for ?
gas exchange threshold
what does RCP stand for ?
respiratory compensation point
describe the RCP performance two mile case performance :
- those with higher RCP had a better two mile rate
- can be used to prove that better RCP = better performance
