Exercise physiology

Question 1

How can we measure metabolic rate and what does this assume?

Answer 1

Oxygen consumption

Assumes that the pulmonary oxygen uptake corresponds to oxygen uptake by the tissues = steady state

Question 2

How do we calculate respiratory rate ?

Answer 2

RR = breaths taken x 60 / time taken for gas collection

Question 3

How do we calculate pulmonary ventilation?

Answer 3

PV = 60 x 1.1 x volume of expired gas / time taken for gas collection

Question 4

How do we calculate mean tidal volume?

Answer 4

PV/RR

Question 5

How do we calculate O2 consumption rate ?

Answer 5

PV x ( 20.83 - %expired O2) x 0.86/ 100

Question 6

How do we calculate CO2 consumption rate ?

Answer 6

PV x % CO2 expired x 0.86/100

Question 7

How do we calculate the respiratory quotant?

Answer 7

CO2 consumption rate/ oxygen consumption rate

Question 8

How does SBP + DBP change at onset of exercise, during exercise and post exercise?

Answer 8

SBP increases linearly with exercise intensity

More blood is pumped out heart, the pressure rises in the blood vessels transporting the blood

Minimal change in DBP

Question 9

What is a normal pulse pressure and how does it change during exercise?

Answer 9

40mmHg

Pulse pressure increases due to increased stroke volume and the speed at which the stroke volume is ejected

Question 10

Why is a high PP a concern?

Answer 10

Can be caused by HBP or atherosclerosis. Often associated with increases risk of heart attack or stroke.

Question 11

How does metabolism change at onset to exercise. during exercise and post exercise?

Answer 11

Glucose is used rapidly when exercise is initiated and increases according to exercise intensity

Question 12

What is ventilatory threshold?

Answer 12

The point at which ventilation increases faster than your VO2 ( volume of oxygen consumed)

Question 13

How does the body increases its metabolic rate during moderate sustained exercise?

Answer 13

Increase in HR and increase in ventilation rate to deliver more O2 to the working contracting muscles

Increased BMR is needed to sustain the increased energy requirements when exercising

Question 14

What happens to the ventilation rate in short high intensity exercise?

Answer 14

No sharper rise in ventilation as oxygen needs to reach the muscles much faster and more CO2 needs to be expired. This type of exercise would also be anaerobic

Question 15

How does the RQ change at rest and during exercise?

Answer 15

At rest the ratio is lower

Increases as exercise intensity increases as the body becomes more reliable on carbohydrates such as glucose

If the RQ is near 1 the person is using mostly carbs

At rest and easy aerobic exercise the respiratory quota is less because the cells are able to use other fuel sources

Question 16

High intensity exercise can cause an RQ of 1.5 or 2. Can you explain the changes in metabolism that may account for such values?

Answer 16

Anaerobic fuel source

CO2 is being produced by other means

The body is undergoing high intensity exercise so lactic acid is produced in anaerobic respiration

Hyperventilation to remove XS CO2

Question 17

Why do patients with diabetes have a lower RQ value?

Answer 17

They have less insulin/decreased insulin sensitivity so less glucose its taken up by the muscles.

The body relies more on fat as a fuel source