Exercise Metabolism W2 Flashcards
How do you measure respiratory exchange ratio?
VCO2/ VO2
When estimating fuel utilisation, when do measurements need to be performed in order to be reflective of gases in tissues?
Steady-state exercise
How much protein is estimated to be used as fuel during exercise?
0
What is the caloric equivalent for oxygen when only fat is used?
4.69Kcal per L
What is the caloric equivalent for oxygen when only carbohydrate is used?
5.05Kcal per L
What is the crossover concept?
The shift from fat to CHO metabolism as a result of increased exercise intensity
What causes the crossover concept?
Recruitment of fast muscle fibres
Increasing blood levels of epinephrine to stimulate glycolysis and lactate production
What does increasing blood levels of epinephrine
to stimulate glycolysis and lactate production do?
Inhibits fat metabolism by reducing the availability of fat as a substate
What factors govern fuel selection during exercise?
Intensity
Duration
How does exercise duration effect fuel utilisation during exercise?
A longer duration increases the rate of lipolysis
What is beta-oxidation?
Process of oxidising fatty acids to Acetyl-CoA
What does glycogen depletion cause?
Decreased glycolysis
Decreased Pyruvate Production
Decreased Krebs-Cycle activity
What is FATmax?
Highest rate of fat oxidation
Reached just before lactate threshold
What is an increased rate of glycogenolysis caused by?
Recruitment of fast-twitch fibres
Elevated blood epinephrine levels
Where does the lactate threshold typically appear in untrained individual?
50-60% VO2max
What is OBLA?
Onset of Blood Lactate Accumulation
Point at which blood lactate reaches >4 mmol/L
What are the possible explanations of an individuals lactate threshold?
Accelerated Glycolysis
Reduced rate of lactate removal from the blood
Recruitment of fast-twitch muscle fibres during intense, rapid exercise
How does accelerated glycolysis caused a lactate threshold?
NADH is produced faster than it is shuttled into the mitochondria= failure to keep up with glycolysis results in pyruvate accepting un-shuttled H+= formation of lactate
How does recruitment of fast-twitch muscle fibres during intense, rapid exercise cause a lactate threshold?
LDH isozyme (exact form of the enzyme) in fast fibres has a greater affinity for attaching to pyruvate= promotes lactate formation
How does reduced rate of lactate removal from the blood cause a lactate threshold?
Blood flow to muscle prioritized over tissues responsible (liver) for removing lactate
How do you work out blood lactate concentration?
Lactate entry into the blood- blood lactate removal
What are each mechanism contributing to lactate threshold independent too?
Whether there is sufficient oxygen
What causes delayed onset muscle soreness?
Likely microscopic injury to muscle fibres
What does microscopic injury do to fibres?
Causes a slow cascade of biochemical events which leads to inflammation and edema within the injured muscle
