Chapter 4 - Exercise Metabolism Flashcards
Oxygen Deficit
Amount of oxygen needed but did not have.
-lack of oxygen uptake is usually at the beginning of exercise. (this can also occur when there is an increase in intensity.)
Oxygen debt
Term used by A.V. Hill
- repayment for O2 deficit at onset of exercise.
- term used interchangeably with EPOC
Excess Post Exercise Oxygen Consumption (EPOC)
Reflects that only -20% of elevated O2 consumption is used to “repay” O2 deficit - thus other factors
-term used interchangeably with oxygen debt (Professor likes this term)
Rapid Portion of O2 debt
- Resynthesis of stored PC + ATP
- Replenishing muscle and blood O2 stores
- Rapid phase of lactate removal (some lactate NOT ALL.)
Slow Portion of O2 debt
- Elevated heart rate and breathing = increased metabolic need
- elevated body temperature = increased metabolic rate
- elevated EPI and NE= increased metabolic rate
- conversion of lactic acid to glucose (gluconeogensis)
EPOC (O2 debt) is greater following higher intensity exercise for these reasons….
- higher body temp. (slow)
- greater depletion of PC + ATP (fast)
- greater blood concentration of lactic acid (fast)
- higher levels of blood epi and norepinephrine
- thus greater HR and breathing (slow)
- need to decrease (lactate, hormones, temp) and replenish ATP/PC stores and O2.
Physiological Factors influencing VO2 max
- maximum ability of CV system to deliver O2 to the muscle.
- ability of muscles to use O2 and produce ATP aerobically
- Endurance training can increase VO2 max.
LDH Isoforms
forms of an enzyme that either goes to pyruvate or lactic acid.
-has 5 isoforms
In low intensity exercises what is the primary source of fuel?
Fats (Lipids)
Mechanisms to explain the lactate threshold.
- low muscle oxygen
- accelerated glycolysis
- recruitment of fast twitch fibers
- reduced rate of lactate removal
Practical Uses of the Lactate Threshold
- Prediction of performance (combined with VO2 max)
- Planning training programs (marker of training intensity, choose a training HR based on LT)
Estimation of Fuel Utilization During Exercise
- Respiratory Exchange Ratio (RER or R)*
one of the methods to estimate fuel utilization during exercise. R = VCO2/VO2
Estimation of Fuel Utilization During Exercise
-R for Fat (palmitic acid)
one of the methods to estimate fuel utilization during exercise. R = VCO2/VO2 = 16 CO2/ 23 O2 = 0.70
R for Carbohydrate (glucose)
one of the methods to estimate fuel utilization during exercise. R = VCO2/VO2 = 6 CO2/6 O2 = 1.0
Fats
What is the primary fuel for low intensity exercise (<30% VO2 max)
Carbohydrates
What is the primary fuel for high intensity exercise (>70% VO2 max)
Muscle Glycogen
- primary source of carbohydrate during high intensity exercise
- supplies much of the carbohydrate in the first hour of exercise
- limited amount of storage within the muscle of glycogen
Sources of Protein During Exercise
Ezymes tht degrade protein (proteases) are activated in long-term exercise.
Lactate as a Fuel Source During Exercise
- can be used as a fuel source by skeletal muscle and the heart. (converted to acetyl - CoA and enters Krebs cycle)
- Can be converted to glucose in the liver (Cori Cycle)
- Lactate Shuttle (lactate produced in one tissue and transported to another.)
The Cori Cycle : Lactate as a Fuel Source
- Lactate (some) produced by skeletal muscle is transported to the liver
- liver converts lactate to glucose (gluconeogenesis)
- glucose is transported back to muscle and used as fuel.
Approximately what percent of ATP is produced by aerobic metabolism>
Almost 100 %
Who is known for the term oxygen debt (repayment for O2 deficit at onset of exercise)?
A.V. Hill
What is anaerobic energy system is the fasted thing used and fastest thing replenished?
Phosphocreatine + ATP
Is lactic acid removed more rapidly with no exercise or light exercise in recovery?
Light exercise
In the first 1-5 seconds of exercise what anaerobic system is utilized to supply ATP?
ATP-Phosphocreatine system
Intense exercise lasting longer than 5 seconds activated what anaerobic system to supply ATP?
Glycolysis
Exercise lasting longer than 45 seconds utilized what system in order to supply the body’s demand for ATP?
A mixture of of ATP-PC system, glycolysis, and aerobic pathways. The longer the activity the more aerobic the metabolism becomes and less anaerobic.
The production of ________ is the cause of muscle fatigue not lactic acid.
Hydrogen Ions
When a steady state of O2 usage is reached less _______is used and more _______ are used.
Carbs (sugars) : Lipids (Fats)
What type of physical training can increase VO2 max?
endurance
What type of muscle twitch fibers have more heart type LDH isoforms and thus produce less lactate?
Slow Twitch Fibers
In high intensity exercises what is the primary source of fuel?
Carbohydrates
What is the crossover concept?
The description of the shift from Fat to Carbohydrates metabolism as exercise intensity increases.
- this is due to the recruitment of more fast-twitch muscle fibers and increasing blood levels of EPI.
