Lab 3

Question 1

What are the three major substrates for energy production

Answer 1

1. carbohydrates
2. fats
3. proteins

Question 2

What are the 3 major substrates stored as in the body

Answer 2

1. carbohydrates –> glycogen (liver and muscle)
2. fat –> triglycerides (adipose tissue and intramuscular depots)
3. protein –> bodily protein (muscle…)

Question 3

What are the major sources of fuel for OXIDATIVE ATP production

Answer 3

fat and carbohydrates

Question 4

what is not considered a major contributer to energy production during exercise… why

Answer 4

protein because your body burns carbs and fat first

Question 5

when does the body increase its role for protein as a fuel source

Answer 5

conditions of muscle glycogen depletion

Question 6

How do you monitor substrate utilization during exercise

Answer 6

indirect calorimetry

Question 7

What does indirect calorimetry work

Answer 7

utilizes measurements of expired CO2 and O2to calculate respiratory exhange ratio (RER)

Question 8

What is RER

Answer 8

espiratory exchange ratio
ratio of (VCO2/VO2)
can be used to estimate substrate utilization

Question 9

how does RER estimate substrate utilization

Answer 9

b/c fats and carbohydrates use and produce different amounts of CO2 and O2

Question 10

How to determine numbers for RER values

Answer 10

Every RER value ahs corresponding caloric equivalent for O2 and estimated contribution of carbs and fats to E contribution

Question 11

What has to be known to calculate total energy expenditure

Answer 11

VCO2/VO2
(carbohydrate + fat)

Question 12

given total energy expenditure what can be calculated

Answer 12

absolute amount of energy production from given substrate can be calculated

Question 13

What does the mitochondria do in the cell for glucose

Answer 13

mitochondria can oxidize glucose at a much higher rate than free fatty acids

Question 14

What happens when exercise intensity increases from mild, to moderate, to hard what is effected – known as what

Answer 14

relative contribution of carbohydrates becomes increasingly important

Question 15

What is the crossover concept

Answer 15

exercise intensity increases and and increase in contribution of carbohydrate as energy source

Question 16

due to adaptations with endurance trainings what happens to the crossover point

Answer 16

it will shift to the right on the graph of substrate utilization versus VO2max to a higher relative and absolute work rate

Question 17

In a untrained individual to a trained athlete how does the crossover experience differ

Answer 17

untrained indiviudal (50% CHO/ 50% fat) occurs at 30% VO2max
trained athlete will experience the crossover at about 40-50% VO2max

Question 18

Why does the delay in “crossover” exist

Answer 18

delay in the “crossover” from fats to carbs is advantageous due to conservation of limited glycogen stores

Question 19

what is important to differentiate for contributions of fat and carbs

Answer 19

differentiate between the absolute and relative contributions of fats and carbs at given work rate

Question 20

At low intensity what happens to the relative (%) contribution of fats…what happens to abs number of total calories –> what happens to absolute amount of fat oxidation

Answer 20

• relative (%) contribution of fats is higher
• abs number of total calories is lower
• absolute amount of fat oxidation is lower (40% of 10kcal/min = 4kcal/min)

Question 21

At moderate intensity what happens to the relative (%) contribution of fats…what happens to relative number of total calories –> what happens to absolute amount of fat oxidation

Answer 21

relative (%) contribuations of fats is lower, absolute number of total calories is higher –> absolute amount of fat oxidation is higher

Question 22

oxygen consumption represents what

Answer 22

total energy expenditure during submaximal, steady-state exercise

Question 23

what happens as exercise intensity increases

Answer 23

VO2 and total energy expenditure increase linearly

Question 24

What is happening in this lab

Answer 24

3, 6-minute exercsie bouts on bicycle ergometer or treadmill at 3 incremental intensities with 5-minute break between each intensity

Question 25

What is the RER for fat in this equation: C16H32O2 + 23O2 –> 16CO2 + 16H2O

Answer 25

R= VCO2/VO2 = 16CO2/23O2 = 0.7

Question 26

What is the RER for carbs in this equation: C6H12O6+ 6O2 –> 6CO2 + 6H2O

Answer 26

R = 6CO2/6O2 = 1.0

Question 27

what are the factos that determine fuel selection

Answer 27

1. intensity
2. duration
3. training status == higher oxidative capacity (crossover shift right (increase fat utilization [longer], increase mitochondrial density, increase capillary density, increase FFA transpo and oxidation, spare glycogen)
4. Diet (CHO supplementation)

Question 28

if you increase intensity what happens to the carbohydrate contribution

Answer 28

increase CHO contribution

Question 29

Where is the “fat burning zone”

Answer 29

oxidation of fat is highest at an exercise intensity of 50% VO2 max and lowest at 100% VO2max

Question 30

as exercise duration increases what happens with fuel utilizaiton

Answer 30

FAT utilization increases and decrease in CHO utilization

Question 31

If you have an acute diet manipulation how does it affect substrate utilization

Answer 31

consuming CHO before or during exercise INCREASES CHO utilizaiton and decreases FAT utilization

Question 32

If you have an chronic diet manipulation how does it affect substrate utilization

Answer 32

• Consuming a high CHO diet increases CHO utilization during submax exercise
• consuming high FAT diet increases FAT utilization

Question 33

When is the best time to ingest CHO before exercise

Answer 33

fuel 2-4 hours before exercise

Question 34

glucose inhibits what to make fats less available

Answer 34

glucose inhibits lipolysis