EXERCISE METABOLISM Flashcards
what happens to lactate released into the bloodstream
-as quickly as lactate enters the bloodstream, it is cleared by the body
-from the blood, lactate goes into different muscle fibers + hepatocytes where it will be oxidized into pyruvate
-muscle cells shuttle the pyruvate into mitochondria to use as fuel
-hepatocytes run the pyruvate through reverse glycolysis/gluconeogenesis
gluconeogensis
run pyruvate backwards through glycolysis to turn into glucose -> released back into bloodstream to be used by muscles
how is lactate oxidized into pyruvate
NAD takes 2 hydrogens from lactate
what does lactate do to ATP supply/demand
-allows type IIa to meet ATP demands so that they don’t fatigue
-PREVENTS fatigue
what causes lactate threshold
lactate produced by anaerobic systems builds up in the blood faster than the body can remove it
how can lactate threshold be used?
it is the intensity you should be training at for optimal adaptations to fibers + to be able to train at higher intensities
oxygen deficit/debt period
-if someone hops on a treadmill without warming up, sudden rise in ATP demands + amount of oxygen consumed increases to meet aerobic metabolism
-in the first few minutes, fiber isn’t consuming enough oxygen to meet ATP demand so during this time it must use anaerobic systems
-this happens because it takes a few minutes to deliver enough oxygen
-this is one of the only times slow twitch will use anaerobic systems
2 theories for oxygen debt period
-it takes time to get sufficient blood/oxygen to fiber + takes time to get aerobic systems running at faster rates
-sympathetic nervous system kicks in when you exercise, causing vasoconstriction; when muscles contract, produce metabolites that cause vasodilation -> this takes time to kick in adding to debt
define EPOC
-when excess oxygen is consumed after exercise is completed
-oxygen consumption stays elevated for minutes/hours/day after exercise
-metabolic rate (consumption/production of ATP) also stays elevated
reasons EPOC occurs (6)
all excess oxygen is used to make ATP in different parts of the body
- phosphagen system used during oxygen debt period must be replenished (turning creatine into phosphocreatine uses ATP)
- lactate produced by anaerobic systems is taken up by hepatocytes to be ran through gluconeogenesis (gluconeogenesis + hepatocytes use ATP)
- sympathetic nervous system causes epinephrine levels to be elevated after exercise -> epinephrine increases metabolic rate
- increased body temperature from exercise increases metabolic rate
- increased respiratory rate increases ATP demand -> breathe more to get more oxygen to cells during exercise
- increased heart rate from exercise increases ATP demand
EPOC relationship to exercise
EPOC is proportional to exercise intensity
-higher intensity -> metabolic rate will stay elevated for longer after exercise is over
what does a metabolic cart measure
-oxygen consumption
-measures amount of air exhaled + % of oxygen in the air
-atmospheric air is 21% oxygen
-21% breathed in is oxygen, rest is nitrogen
-17% exhaled is oxygen
-SO- you consumed 4% oxygen
VO2 max
-maximal amount of oxygen that all cells in the body consume
-measure of aerobic fitness -> endurance athletes have a high VO2 max
how do you get to a true VO2 max
-you must get to a point when you increase intensity of exercise + don’t consume more oxygen than you did at previous intensity; implies you have maxed out aerobic system; objective is to get to plateau
-all fibers are in tetanus at a true VO2 max
measuring VO2 max using a stress test
start at a walking pace + progressively increase the intensity ->
as faster twitch fibers are recruited, ATP + oxygen consumption increase ->
there is a point where oxygen consumption will stop rising + there is a plateau
