Physiology of endurance events Flashcards Preview

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Flashcards in Physiology of endurance events Deck (17)
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1
Q

define the term performance vO2

A

the O2 consumption which can be maintained for a given period of time

the percentage of VO2 max which an athlete can run at

level of aerobic metabolism which can be maintained

2
Q

explain the concept of performance O2 deficit

A

the difference between the amount of energy required at the start of a race and the amount of energy which can be provided by aerobic metabolism

develops because aerobic metabolism is slow to switch on, so doesn’t meet race demands at the start

3
Q

explain the concept of efficiency in relation to endurance running

A

= the oxygen cost of generating a given running speed/power output

so interacts with performance VO2 to determine the speed at which the athlete can run at

lower economy/ efficiency is better!!!

4
Q

explain why the respiratory system could be considered to be a limiting factor of VO2 max when carrying out maximal exercise

A

at these intensities, elite athletes have been shown to undergo arterial desaturisation due to high cardiac output = reduced red cell transit time in the lungs

5
Q

what is the Fick equation for VO2

A

VO2 = Q x (a-v O2 difference)

Q = cardiac output

6
Q

why is cardiac output considered to be the main factor which limits VO2max

A

because the muscle’s capacity for blood flow far exceeds the hearts capacity to pump blood

7
Q

describe the study which demonstrates that CO is the limiting factor of VO2 max

A

isolated the quads and measured the change in blood flow with exercise

3kg of muscle had a blood flow of 6-7l/min

normalised this gives 200ml/kg/min of muscle blood flow

whole body exercise e.g running uses around 30kg of muscle which would require around 60l/min of blood

heart could never produce this, max around 5l

8
Q

why are metabolic processes not considered to be limiting factors of VO2 max

A

flux of pyruvate which is possible, through pyruvate dehydrogenase is sufficient to meet demands of the muscle

9
Q

how does physical training lead to gains in VO2 max?

A

increases CO

increases rate of O2 extraction from the blood

10
Q

explain the benefit of having a better running economy in two different ways

A

1) for a given speed, use less VO2 and therefore less energy
2) for a given VO2, can run at a faster speed

11
Q

give two reasons why a better running economy may lead to an increased time to fatigue

A

1) less energy required to run at a given speed therefore slower depleation of glycogen
2) less heat production for a given running speed therefore less thermal stress on the body

12
Q

define the following:
gross efficiency

net efficiency

work efficiency

delta efficiency

A

all energy expenditure including that at rest

energy expenditure - expenditure at rest

energy expenditure - rest and expenditure linked to unload pedaling

change in energy expenditure when changing work rate

13
Q

which muscle fibre type is more efficient and explain the evidence which shows this

A

type 1

athletes with a higher percentage of type 1 fibres had similar performance VO2 to those with more type 2 but had a higher performance power output

i.e higher power output for similar VO2

14
Q

can running economy be improved with training and what evidence is available to show this

A

yes can get slight improvements over long periods of time

Paula Radcliff showed a decrease in the VO2 when running at a set speed over a period of 5 years without a change in her VO2 max

15
Q

explain the current theory regarding whether or not a <2hr marathon is possible

A

yes
models suggest that a runner with a good VO2 max, who can run at a high % of this and had exceptional economy can do it

but would need exceptional values in all 3

is rare to find exceptional VO2 max and economy in the same person

16
Q

what is the most important factor for determining performance in endurance events

cite evidence from comparison between marathon runners and long distance runners which supports this

A

running economy

marathon runners have lower VO2 max but better running economy vs long distance runners

17
Q

compare the variables contributing to endurance performance in erterian vs spanish runners and explain why erterian runners perform better in marathons

A

spanish have a better VO2max and can run at a higher percentage of their VO2 max therefore can run at a faster speed when running at LT

however, at 21km/h whcih is world record pace erterian have a much better running economy