Aerobic Performance Flashcards
What is aerobic energy?
where oxygen is the final electron acceptor in ETC
where is aerobic energy produced?
mitochondria
Oxygen doesn’t directly resynthesise ATP so what does it do?
determine the maximal rate of aerobic ATP resynthesise
where is the ETC membrane in mitochondria
inner membrane
Simplified ETC -
NADH+H - hydrogen released, NAD leaves, electrons passed down chain and then accepted by 02 and form H20 w/ H
What happens in ETC when 02 is limited?
chain can’t finish so build up of reduced NADH+H
How does NADH+H build up effect the krebs cycle
flux is reduced
therefore more anaerobic energy turnover (= lactate ^ PH down, perf down)
what is the fick equation?
VO2 max = Q max x a-v02 diff max
(Q max = SV max x HR max) (delivery)
(a-v02 diff max = venous 02 content - arteriole 02 content) (extraction)
Central limitation examples
- pulmonary diffusion
- max CO
- bloods carrying capacity
Peripheral limitation examples
extraction & utilisation of 02 delivered to muscles
Central limitation evidence
Arm work tests produce 65-75% of VO2max
Arm and leg work combined VO2max is the same
limitation must be central because if it was peripheral much high VO2max values would be expected
Further central limitation evidence
^ O2 = ^ VO2 max
^ RBC = ^ VO2 max
and reversed
Peripheral limitation evidence
Single leg training study - significant increase in VO2 max in trained leg - due to improved mitochondrial volume and oxidative enzymes
(only relevant for smaller muscle groups)
what was the traditional test protocol and what did it lead too?
discontinued series of work/speed steps
plateau in data during final stages
(also time consuming and ill suited for clinical populations)
what is the new V02 max test?
Ramp incremental test with breath by breath gas analysis
What is the problem with V02 peak tests?
cannot discriminate among subjects who give up due to lack of motivation or discomfort ect in pre training tests
How to fix V02 peak test with secondary critera?
RER above 1, 1.10, 1.15
HR < 10 b/min or < 5% of age predicted max
Blood lactate 8-10 mM
How to fix V02 peak test with verification exercise test
exhausting bout conducted just above/below peak power attained of ramp test after a short rest
What is a problem with using secondary critera?
Can under estimate V02 due to individual differences
What is the gas exchange threshold?
An indirect measure of the lactate threshold
How do we find blood lactate threshold
identify first break point on graph
Why is lactate threshold important?
Shows % of V02max that can be sustained for endurance exercise
predicts endurance performance
can be used to optimise training
How is lactic acid produced?
pyruvate production exceeds rate of mitochondria accepting pyruvate
or
insufficient 02 to re-oxidised NADH
What happens once lactic acid is formed
Immediately dissociates into hydrogen and lactate ions
What does increase H+ ions in muscle cause
Acidosis - reduced pH and fatigue
How are H+ ions buffered
H+ accepted by blood bicarbonate forming carbonic acid and then Co2 and H20
