Metabolic Response to exercise Flashcards
almost 100% of ATP is produced by what type of metabolism
aerobic
what is the resting O2 consumption
.25L/min
what 2 things increase rapidly when you go from rest to exercise transitions
ATP production and Oxygen uptake
how long does it take to reach a steady state when you begin to exercise
1-4 minutes
define oxygen deficit
lag in oxygen uptake at the beginning of exercise
compare the oxygen deficit in trained and untrained subjects
- Trained: have a lower oxygen deficit
- their aerobic bioenergetic capacity is better
- results in less production of lactate and H+ - untrained: have higher levels of oxygen deficit
define steady state
when your ventilation levels off
define oxygen debt
term used to describe recovery from exercise
-repayment for O2 deficit at onset of exercise
what does EPOC stand for and what is it used to describe
excess post-exercise oxygen consumption
-repayment for O2 deficit at onset of exercise
what is involved in the rapid portion of O2 debt
- resynthesis of stored PC
2. replenishing of muscle and blood O2 stores
what is involved in the slow portion of O2 debt
- elevated heart rate and breathing=energy need
- elevated body temp=metabolic rate
- elevated epinephrine and norepinephrine metabolic rate
- conversion of lactic acid to glucose
do you ever reach a steady state during intense exercise?
no because your heart rate cant catch up to the ventilation
when is EPOC the greatest
following higher intensity exercise
what does increase heat during exercise do
it lowers the affinity between oxygen and hemoglobin
define the anaerobic threshold
lactate levels increase
what was the classical theory regarding the removal of lactic acid following exercise
majority of lactic acid is converted to glucose in the liver
what is the more recent evidence regarding the removal of lactic acid following exercise
70% of lactic acid is oxidized and used as a substrate by the heart and skeletal muscle
20% is converted to glucose
10% is converted to amino acids
when is lactic acid removed more rapidly
during light exercise
-optimal intensity is 30-40$ VO2 max
what are the metabolic responses to short term intense exercise
- First 1-5 seconds, ATP through ATP-PC system is used
- longer than 5 seconds: glycolysis
- longer than 45 seconds: ATP production through aTP-PC, glycolysis, and aerobic systems
at 60 seconds 70% anaerobic
at 2 minutes 50% anaerobic
what are the metabolic responses to prolonged exercise
- exercise lasting longer that 10 minutes
- aerobic metabolism
- steady state oxygen uptake can generally be maintained during submaximal exercise - in a hot/humid environment or high intensity
- upward drift in oxygen uptake over time due to increased body temp and epinephrine and norepinephrine
how long does oxygen uptake continue to increase
increases linearly until VO2 max is reached which means that even if you continue to increase the work rate, you cannot increase you O@ intake
how is VO2 max affected
by genetics and training
what are 2 physiological factors influencing VO2 max
- max ability of cardiorespiratory system to deliver oxygen to the muscle
- ability of muscles to use oxygen and produce ATP aerobically
what are four things that explain the lactate threshold
- low muscle oxygen
- accelerated glycolysis
- recruitment of fast-twitch fibers
- reduced rate of lactate removal
you want to train above threshold in order to improve
what are practical uses of the lactate threshold
- prediction of performance combined with VO2 max
- planning training programs
- choose training HR based on LT
does lactate cause muscle soreness
no, soreness is due to delayed onset muscle soreness
during low intensity exercise (<30$ VO2 max) what is the primary fuel being used
fats
during high intensity exercise (>70% VO2 max) what is the primary fuel being used
carbohydrates
what is the crossover concept
describes the shift from fat to CHO metabolism as exercise intensity increases due to the recruitment of fast muscle fibers and increasing blood levels of epinephrine
is low intensity best for burning fat?
no, the total fat oxidation is low
-during more intense exercise total fat oxidation is higher and total energy expended is higher
What is the fuel selection during prolonged low intensity exercise
-it is a shift from carb to fat metabolism dur to an increased rate of lipolysis
(breakdown of triglycerides into glycerol and FFA
-stimulated by rising blood levels of epinephrine
muscle glycogen
- primary source of carbs during high intensity exercise
2. supplies much of the carbs in the first hour of exercise
blood glucose
from liver glycogenolysis
- primary source of carbs during low intensity exercise
- important during long duration exercise as muscle glycogen levels decline
what are 3 branched chain amino acids
leucine
isoleucine
valine
what are 2 sources of fat during exercise
- intramuscular triglycerides
2. plasma FFA
intramuscular triglycerides
primary source of fat during higher intensity exercise
plasma FFA
- from adipose tissue lipolysis
- FFA converted to acetyl-CoA and enters krebs cycle
- primary source of fat during LOW intensity exercise
- becomes more important as muscle triglyceride levels decline in long duration exercise
sources of protein during exercise
proteins broken down into amino acids
- muscle can directly metabolize branch chain amino acids and alanine
- liver can convert alanine to glucose
what is the enzyme that degrades proteins
proteases
describe lactate as a fuel source
- can be used as a fuel source by skeletal muscle and the heart
- it is converted to acetly-CoA and enters the krebs cycle - can be converted to glucose in the liver(cori cycle)
- lactate shuttle
- lactate produced in one tissue and transported to another
