Lab 3 Flashcards
What are the three major substrates for energy production
- carbohydrates
- fats
- proteins
What are the 3 major substrates stored as in the body
- carbohydrates –> glycogen (liver and muscle)
- fat –> triglycerides (adipose tissue and intramuscular depots)
- protein –> bodily protein (muscle…)
What are the major sources of fuel for OXIDATIVE ATP production
fat and carbohydrates
what is not considered a major contributer to energy production during exercise… why
protein because your body burns carbs and fat first
when does the body increase its role for protein as a fuel source
conditions of muscle glycogen depletion
How do you monitor substrate utilization during exercise
indirect calorimetry
What does indirect calorimetry work
utilizes measurements of expired CO2 and O2to calculate respiratory exhange ratio (RER)
What is RER
espiratory exchange ratio
ratio of (VCO2/VO2)
can be used to estimate substrate utilization
how does RER estimate substrate utilization
b/c fats and carbohydrates use and produce different amounts of CO2 and O2
How to determine numbers for RER values
Every RER value ahs corresponding caloric equivalent for O2 and estimated contribution of carbs and fats to E contribution
What has to be known to calculate total energy expenditure
VCO2/VO2
(carbohydrate + fat)
given total energy expenditure what can be calculated
absolute amount of energy production from given substrate can be calculated
What does the mitochondria do in the cell for glucose
mitochondria can oxidize glucose at a much higher rate than free fatty acids
What happens when exercise intensity increases from mild, to moderate, to hard what is effected – known as what
relative contribution of carbohydrates becomes increasingly important
What is the crossover concept
exercise intensity increases and and increase in contribution of carbohydrate as energy source
due to adaptations with endurance trainings what happens to the crossover point
it will shift to the right on the graph of substrate utilization versus VO2max to a higher relative and absolute work rate
In a untrained individual to a trained athlete how does the crossover experience differ
untrained indiviudal (50% CHO/ 50% fat) occurs at 30% VO2max
trained athlete will experience the crossover at about 40-50% VO2max
Why does the delay in “crossover” exist
delay in the “crossover” from fats to carbs is advantageous due to conservation of limited glycogen stores
what is important to differentiate for contributions of fat and carbs
differentiate between the absolute and relative contributions of fats and carbs at given work rate
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
- 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)
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
relative (%) contribuations of fats is lower, absolute number of total calories is higher –> absolute amount of fat oxidation is higher
oxygen consumption represents what
total energy expenditure during submaximal, steady-state exercise
what happens as exercise intensity increases
VO2 and total energy expenditure increase linearly
What is happening in this lab
3, 6-minute exercsie bouts on bicycle ergometer or treadmill at 3 incremental intensities with 5-minute break between each intensity
What is the RER for fat in this equation: C16H32O2 + 23O2 –> 16CO2 + 16H2O
R= VCO2/VO2 = 16CO2/23O2 = 0.7
What is the RER for carbs in this equation: C6H12O6+ 6O2 –> 6CO2 + 6H2O
R = 6CO2/6O2 = 1.0
what are the factos that determine fuel selection
- intensity
- duration
- 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)
- Diet (CHO supplementation)
if you increase intensity what happens to the carbohydrate contribution
increase CHO contribution
Where is the “fat burning zone”
oxidation of fat is highest at an exercise intensity of 50% VO2 max and lowest at 100% VO2max
as exercise duration increases what happens with fuel utilizaiton
FAT utilization increases and decrease in CHO utilization
If you have an acute diet manipulation how does it affect substrate utilization
consuming CHO before or during exercise INCREASES CHO utilizaiton and decreases FAT utilization
If you have an chronic diet manipulation how does it affect substrate utilization
- Consuming a high CHO diet increases CHO utilization during submax exercise
- consuming high FAT diet increases FAT utilization
When is the best time to ingest CHO before exercise
fuel 2-4 hours before exercise
glucose inhibits what to make fats less available
glucose inhibits lipolysis
