Lab Exam 1- Lab 3 Flashcards
as exercise intensity increases from mild (25% VO2 max) to moderate (65% VO2 max) to hard (80% VO2 max), what becomes increasingly important
relative contribution of CARBS
what % of VO2 max is considered mild intensity
25% VO2 max
what % of VO2 max is considered moderate intensity
65% VO2 max
what % of VO2 max us considered high intensity
80% VO2 max
crossover concept
as exercise intensity increases, there is an increase in the contribution of CARBS as an energy source
every RER has a corresponding
caloric equivalent for O2 and the estimated contribution of carbs and fat to energy production
given total energy expenditure what can we calculate
the absolute amount of energy production from a given substrate
how and where are carbs stored
in the liver and muscle as glycogen
how and where are lipids stored
as triglycerides in adipose tissue and intramuscular deposits
how do we monitor substrate utilization during exercise in this lab
via indirect calorimetry
indirect calorimetry
uses accurate measurements of expired CO2 and O2 to calculate respiratory
O2 consumption represents
the total energy expenditure during submaximal, steady-state exercise, and as exercise intensity increases, VO2 and total energy expenditure increase linearly
relative vs absolute contributions of fats and carbs at low intensity
relative contribution of fats is higher, but the absolute number of total calories is loweer
absolute amount of oxidation is lower
relative vs absolute contributions of fats and carbs at moderate intensity
the relative contribution of fats is lower, but the absolute number of total calories is higher
absolute amount of oxidation is higher
RER
respiratory exchange ratio
VCO2/VO2
used to estimate substrate utilization because fats and carbs use and produce different amounts of CO2 and O2
three major substrates for energy production
carbs
fats
proteins
what are we measuring in this lab
substrate utilization at 3 different intensities either on a cycle OR on the treadmill
what happens with an active muscle cell
mitochondria can oxidize glucose at much higher rate than free fatty acids
when does an untrained individual reach their crossover point (50% carbs/50% fat)
30% VO2 max
when is protein used as a fuel source
under conditions of muscle glycogen depletion (exhaustive exercise or starvation)
when VCO2/VO2 is known,
the total energy expenditure (carb+fat) can be calculated
when will a trained athlete reach their crossover point
40-50% VO2 max
where and how are proteins stored
in muscle as bodily protein
where do substrates for energy production come from
foodstuffs but stored in various forms
which substrate is not considered a major contributor to energy production during exercise
protein
why is it advantageous to have a delay in crossover (carbs into fats) in trained individuals
conservation of limited glycogen stores
what is required to calculate RER
must be at steady state
non protein
why does RER exceed 1.0 at higher workloads
hyperventilation
do CHO yield less or more energy per LO2
CHO = more energy (kcal) per LO2
factors that determine fuel selection
intensity
duration
training status
diet
what does training status do to oxidative capacity
increases
what happens to crossover point with training
crossover shifts right (greater %VO2 max) which increases fat utilization
what does training do to mitochondrial density
increases
what does training do to capillary density
increases
what does training do to FFA transport and oxidation
increases
training affects on glycogen use
spares glycogen- use less
fat burning zone
the highest oxidation of fats occurs at 50% exercise intensity (% VO2 max)
Absolute amounts (kcal/hr)
As exercise duration increases what happens to contribution of Fats/CHOs
there is an increase in FAT utilization and a decrease in CHO utilization
acute diet manipulations affects on substrate utilization
consuming CHO before or during ACUTE exercise increases CHO utilization and decreases FAT utilization
chronic diet manipulations affects on substrate utilization
consuming a high CHO diet increases CHO utilization during submaximal exercise, whereas consuming a high FAT diet increases FAT utilization
why does CHO intake reduce FAT utilization and what are the implications for performance
glucose inhibits lipolysis which decreases the number of fats that are available