Energy balance and substrate metabolism 2

Question 1

What is measured in direct calorimetry?

Answer 1

The heat produced by someone

Question 2

Issues with a direct calorimetry machine?

Answer 2

Need to be quite small (people cant move), very expensive

Question 3

What does indirect calorimetry measure?

Answer 3

Oxygen consumption and carbon dioxide production

Question 4

Ways to measure energy expenditure in free living conditionds?

Answer 4

Self report questionnaire, doubly labelled water, pedometers, accelerometers, accelerometry and heart rate combined (aciheart)

Question 5

Benefits of self report energy expenditure?

Answer 5

Easy to administer to a large group, low cost

Question 5

Issues of self report energy expenditure?

Answer 5

Reporting bias–> underreport intake and overreport exercise

Question 6

Benefits of doubly labelled water?

Answer 6

Precise and accurate

Question 7

Issues with doubly labelled water?

Answer 7

Expensive and technically challenging-> cannot be used on a large group

Question 8

What does the AciHeart measure?

Answer 8

Accelerometry and heart rate

Question 9

How does doubly labelled water work?

Answer 9

Ingest a dose of water with heavier H and O isotopes. O loss is steeper when measured as it is lost in CO2 and H20 whereas H is only lost in H2O. Difference between the two is the average CO2 produced over that time period

Question 10

Strengths of DLW?

Answer 10

Doesnt need to rely on accurate patient reporting

Question 11

Limitations of DLW?

Answer 11

Ratio of CO2 production to O2 consumption varied depending on diet of person, so O2 consumption isnt an exact measure it is inferred

Question 12

Issue with using DLW at high exercise intensities?

Answer 12

High exercise intensity results in acidosis (H+ production) which is buffered by bicarbonate system–> produces CO2 from non-metabolic processes

Question 13

Fuel source issue w/ DLW?

Answer 13

Can be oxidising things like lactate, ketone bodies, protein as well as Carbs and Fat

Question 14

Tissue specific measurement of substrate metabolism method?

Answer 14

Tracer based–> infuse a labeled form of glucose into a vein, ingest another form of carb–> measure exogenous carb oxidation

Question 15

What can be measured from tissue specific measurement of substrate metabolism?

Answer 15

Exogenous carb production

Question 16

Link between exercise intensity and fuel consumption?

Answer 16

At higher intensity exercises, carbohydrate fuels are used more than fats

Question 17

Effect of duration of exercise on fuel consumption?

Answer 17

Decrease in carb use and an increase in fat use

Question 18

Which metabolic fuels are blood based?

Answer 18

Plasma glucose, circulating FFA

Question 19

Contribution of muscle based fuels as exercise duration increases?

Answer 19

Decreases

Question 20

Why does the contribution of muscle based fuels decrease as exercise duration increases?

Answer 20

Muscle fuels are depleted over the course of exercise so the longer it goes on the less readily available they are

Question 21

What effect on fuel use does ingesting Cho have?

Answer 21

Decrease fat oxidation and increase carb oxidation

Question 22

Which sex has the greater capacity for fat oxidation?

Answer 22

Women

Question 23

Effect of VO2max on muscle glycogen storage?

Answer 23

Increases it

Question 24

Effect of a high carb diet on glycogen storage capacity?

Answer 24

Increases it

Question 25

What effect does a higher glycogen conc pre exercise have on glycogenolysis?

Answer 25

More glycogen at start of exercise = more glycogen is used

Question 26

What must be done to the triacyl glycerides in fat before they can be used as a fuel by muscle?

Answer 26

Hydrolysed

Question 27

Product of hydrolysis of triacylglycerides?

Answer 27

Glycerol and FAs

Question 28

Which transport protein allows FAs to get into muscle mitochondria?

Answer 28

CPT1

Question 29

Which enzyme hydrolyses VLDLs and chylomicrons?

Answer 29

Lipoprotein lipase (LPL)

Question 30

What could limit NEFA availability?

Answer 30

Adipose tissue blood flow

Question 31

Transarcolemal meaning?

Answer 31

Transport across the muscle membrane

Question 32

What limits fat oxidation at high exercise intensities?

Answer 32

Transport into mitochondria