Limits to exercise tolerance 2

Question 1

Arguments against lungs being a limiting factor in VO2max?

Answer 1

Alveolar area is v large, ventilation increases more than oxygen uptake, pp of oxygen in alveoli and arteries is maintained at VO2max

Question 2

Arguments in favour of lungs being a limiting factor in VO2max?

Answer 2

At normoxia, the oxygen saturation of haemoglobin declines as the intensity of exercise does, hypoventilation, mechanical constraints

Question 3

What is hyperoxia?

Answer 3

Atmospheric oxygen partial pressure is higher than usual

Question 4

What is normoxia?

Answer 4

Atmospheric oxygen partial pressure is the same as usual

Question 5

What is hypoxia?

Answer 5

Atmospheric oxygen partial pressure is lower than usual

Question 6

What is hypoventilation?

Answer 6

breathing that is too shallow

Question 7

How can hypoventilation be a limitation of VO2max?

Answer 7

Someone may have the capacity for a certain oxygen uptake but arent sensitive enough to the stimuli (exercise) to increase the ventilation rate

Question 8

What are the axis of a flow volume loop?

Answer 8

Flow rate in L/s on Y axis, volume in L on the x axis

Question 9

How to create a flow volume loop?

Answer 9

Maximal inspiration then forcefully expire all air in lungs as quickly and as hard as possible

Question 10

How can we test whether lung function is a limiting factor of VO2?

Answer 10

Changing density of inspired air

Question 11

What was observed as a result of changing the density of inspired air to see whether lungs are limiting or not?

Answer 11

Less dense air overcomes the limitation of lungs reaching expiring capacity

Question 12

What is pulmonary oedema?

Answer 12

Swelling in the lungs

Question 13

How does pulmonary oedema negatively affect gas exchange in the lungs?

Answer 13

The swelling causes the interstitial space between the alveoli and capillary to increase thus gas exchange takes longer

Question 14

How can alveolar capillary diffusion limit VO2max?

Answer 14

Only one RBC can pass through a capillary at a time. In untrained this is 0.4-0.5s whereas in trained it is <0.4. Longer means more time to take oxygen to blood so lower VO2max

Question 15

Are lungs a limiting VO2max factor in untrained individuals?

Answer 15

Not a huge amount of evidence to support it

Question 16

Are lungs a limiting VO2max factor in trained individuals?

Answer 16

Some evidence that this may be true

Question 17

What is hyperpnea?

Answer 17

Increased ventilation

Question 18

What is the cost of exercise hyperpnea?

Answer 18

Respiratory muscles have a power output of around 50 watts

Question 19

WHat is unique about respiratory muscles?

Answer 19

They can produce a lot of force relative to their size

Question 20

What is proportional assisted ventlation?

Answer 20

Participant begins inhaling–> rest of air is forced into lungs via machine

Question 21

What is RPE?

Answer 21

Rating of perceived exertion

Question 22

What happens to leg RPE in unloaded (proportional assisted ventilation) condition?

Answer 22

It is a lot lower than load or control

Question 23

How to load inhalation?

Answer 23

Have the participant lift a small weight when they breathe in–> lungs and respiratory muscles have to work harder

Question 24

What is an MIP?

Answer 24

Maximum inspiratory mouth pressure test

Question 25

What does a MIP do?

Answer 25

Measures the pressure someone can generate at their mouth when they breathe in

Question 26

What happens to MIP following exercise?

Answer 26

It decreases

Question 27

Issue with doing an MIP after endurance exercise?

Answer 27

Athletes may be tired and so might not inspire as hard as they can

Question 28

What is a volitional measure?

Answer 28

Relating to someones will

Question 29

How is the diaphragm isolated when measuring its exertion?

Answer 29

Using a nasoesophageal catheter

Question 30

How does a nasoesophageal catheter work work?

Answer 30

It goes up the nose, down the throat and into the stomach where there is two pressure transducers, one in the stomach and one in the oesophagus. WHen diaphragm contracts it moves down which increases stomach pressure and decreases esophageal pressure

Question 31

What is the respiratory metaboreflex?

Answer 31

When respiratory muscles become fatigued, it sends a signal that changes blood flow to other muscles

Question 32

What is observed regarding leg blood flow when work of breathing is increased?

Answer 32

It decreases

Question 33

When using a nasoesophageal catheter, where are the pressure transducers?

Answer 33

Stomach and oesophagus

Question 34

What is observed regarding leg VO2 when work of breathing is increased?

Answer 34

It decreases

Question 35

How efficient is muscle O2 extraction?

Answer 35

Very

Question 36

Why is muscle oxygen extraction unlikely to limit VO2max?

Answer 36

At high intensity exercise the difference in oxygen conc between the artery entering the muscle and the vein leaving the muscle is high meaning it is very efficient

Question 37

What explains most of the variance in VO2max between people?

Answer 37

Cardiac output

Question 38

What explains the early increase in VO2max with exercise training?

Answer 38

Plasma volume

Question 39

What is observed in the blood in the first week after beginning training?

Answer 39

Rapid increase in plasma volume

Question 40

How to artificially increase plasma volume?

Answer 40

Dextran infusion

Question 41

What is observed in the VO2max of people who have had their blood plasma volume artificially increased as a result of a dextran infusion?

Answer 41

An increase of ~4%

Question 42

How does dehydration affect performance?

Answer 42

It leads to a lower plasma volume which leads to lower blood flow and stroke volume

Question 43

In most people, what is the correlation between VO2max and performance time in a a marathon?

Answer 43

High

Question 44

In elite athletes, what is the correlation between VO2max and performance?

Answer 44

Not as strong as in the general population

Question 45

Why may the VO2max of elite athletes not perfectly correlate to performance?

Answer 45

other factors such as mechanical efficiency, running economy etc

Question 46

Which test could be better than VO2max for elite athetes?

Answer 46

Lactate threshold

Question 47

What was observed regarding time to fatigue differences at 70%VO2max in low, mixed and high CHO diets?

Answer 47

The low CHO diet performed the worst with around 1 hr, the high performed the best between 2 and 5 hrs

Question 48

Correlation between CHO content in diet and muscle glycogen levels?

Answer 48

Higher CHO content in diet means a higher muscle glycogen content

Question 49

What was observed when looking at the time when muscle glycogen depletion occurs in placebo and CHO-fed groups during exercise?

Answer 49

They reach muscle glycogen depletion at the same time (3hrs)

Question 50

Why could CHO-fed people exercise for longer than placebo despite reaching muscle glycogen depletion at the same time?

Answer 50

Taking on more CHO means it no longer becomes a reason for fatigue

Question 51

What role can muscle glycogen have other than a fuel?

Answer 51

A signalling molecule

Question 52

Subsarcolemmal region meaning?

Answer 52

Below the sarcolema

Question 53

Which type of muscle glycogen storage is most closely associated with fatigue?

Answer 53

Intramyofibrillar

Question 54

How does a lack of muscle glycogen affect calcium?

Answer 54

It affects its release rate

Question 55

Which out of glycogen, glucose, FAs can generate ATP the fastest?

Answer 55

Glycogen

Question 56

What is McArdles disease?

Answer 56

Lack of enzymes required to break down muscle glycogen

Question 57

Which fuel is more efficient, carbs or fats?

Answer 57

Carbs