o2 deficit
define o2 deficit
energy demands at onset of exercise that are not being met by the aerobic systems
what is the term used for when vo2 increases during constant-load exercise AFTER a steady-state has been reached (especially during hot and humid conditions)
o2 drift
if a person completed endurance training for a couple months, what would you expect to happen to the size of the EPOC
decrease at constant intensity, returns to normal faster
increase at increasing intensity because it takes longer to return to normal
what is the formula/ratio
to what extent do amino acids (protein) contribute to energy needs during exercise
2-5% total energy, could increase to 5-10% late in prolonged exercise (starvation etc)
what does o2 deficit represent metabolically speaking
when you exercise, your aerobic systems don't have ATP made yet, the anaerobic systems are making up for that demand in energy due to the o2 deficit
when we exercise, core body temp increases, this creates stress in the body, which causes the release of hormones like epi and norepi
what does vo2max represent
the most oxygen someone can breathe/respire during exercise
what happens to proportional utilization of carbohydrates vs fats with increasing exercise intensity
-as intensity increases, we use more carbs
-fat utilization does not go down as intensity goes up, but carbohydrates skyrocket and this creates difference in % utilization
in what ways (direct and indirectly) do amino acids contribute energy demands during exercise
-muscle can directly metabolize branch chain amino acids and alanine
-source of krebs cycle intermediates
-liver can convert alanine to glucose
what does o2 deficit tell us about energy metabolism (contribution to work demands over duration of exercise)
tells us that at onset of exercise, anaerobic is the main contributor until steady state is reached and aerobic is ready to take over
define epoc
excess post-exercise oxygen consumption
why does vo2 level off at max, despite continued increases in workload
because the aerobic system is maxed out so vo2 can't increase, but anaerobic is now major contributor
-recruitment of fast twitch fibers
-increasing epi stimulates glycogen breakdown
-at higher intensities, reduced FFA mobilization
discuss the specific contributions/changes in muscle fuel sources as exercise duration increases
-muscle glycogen contribution decreases as time increases (drastic)
-plasma/blood glucose increases as time increase (drastic)
-plasma FFA increases as time increases (not drastic)
-muscle TG decreases as time increases (not drastic)
how does aerobic training alter the size of the o2 deficit, and the speed at which a vo2 steady state is reached
aerobic training decreases the size of the o2 deficit because mitochondrial density increases and speeds up the process of getting energy from aerobic systems
steady state is reached sooner because aerobic is ready sooner
what factors contribute to this continued elevation in vo2 after the cessation of exercise
-resynthesis of PC in the muscle
-lactate conversion to glucose
-restoration of muscle and blood oxygen stores
-elevated body temperature
-post exercise elevation of HR and breathing
-elevated hormones
what physiological factors cause the lactate threshold during incremental exercise
-low muscle o2
-accelerated glycolysis due to epinephrine being released at a higher rate due to body stress
-recruitment of fast-twitch fibers
-reduced rate of lactate removal
discuss specific changes in % muscle fuel sources as exercise intensity changes from low to high
low:
-majority fat, minority carb
-majority plasma FFA at light intensity
moderate:
-50/50 carbs and fats
-plasma FFA and muscle glycogen about even at moderate intensity
vigorous:
-muscle glycogen is main carb source
-fat stays about the same at each intensity
can carbohydrate intake during prolonged exercise improve performance? why?
yes,
enhanced CHO oxidation late in exercise, preservation of endogenous CHO, exogenous CHO oxidation
the space between the demands and the line
which factors are fast vs slow portion
fast:
-resynthesis of PC in muscle
-restoration of muscle and blood oxygen stores
slow:
-lactate conversion to glucose
-post exercise elevation of HR and breathing
-elevated body temperature
-elevated hormones
at the intensity where lactate threshold occurs, estimate the % of energy coming from aerobic/anaerobic metabolism
more coming from aerobic than anaerobic
why does expressing fat utilization as a % of total energy potentially misrepresent the extent to which fats are used during moderate intensity exercise
makes it look like fat utilization is going down as intensity goes up, but in reality it's not changing, only carbs are going up
no