Lab 3: Substrate Utilization Flashcards
storage form and location for carbohydrates
glycogen in the liver and muscle
storage form and location for fats
triglycerides in adipose tissue and intramuscular deposits
storage form and location for proteins
bodily protein in muscle
major sources of fuel for oxidative ATP production
carbs and fats
when is protein used as a fuel source
conditions of muscle glycogen depletion (i.e. exhaustive exercise or starvation)
define respiratory exchange rate (RER)
ratio of carbon dioxide produced over oxygen consumed (VCO2/VO2)
what technique can be used to calculate RER in the lab
indirect calorimetry
how can the RER be used to estimate substrate utilization?
fats and carbohydrates use and produce different amounts of O2 and CO2
when RER is known, what else can be calculated?
the total energy expenditure (carb + fat)
when total energy expenditure is known, what else can be calculated?
absolute amount of energy production from a given substrate
are free fatty acids or glucose oxidized faster?
glucose
describe the crossover concept
as exercise intensity increases, there is an increase in the contribution of carbohydrates as an energy source
for a trained individual, what happens to the crossover point (on a graph of % VO2 max vs percent energy from fat and carbs)
crossover point shifts right
where is the crossover point (50% CHO/ 50% fat) for an untrained individual?
30% VO2 max
where is the crossover point (50% CHO/ 50% fat) for a trained individual?
40-50% VO2 max
why is the delay in the crossover point advantageous for trained individuals?
it helps conserve limited glycogen stores
distinguish between absolute and relative contributions of fat and carbohydrate at a given work rate
at a low intensity, the relative (%) contribution of fats is higher, but the absolute number of total calories is lower (the absolute amount of fat oxidation is lower (80% of 4 kcals/min = 3.2 kcals/min)
at a moderate intensity, the relative (%) contribution of fats is lower, but the absolute number of total calories is higher (40% of 10 kcals/min = 4 kcals/min)
oxygen consumption represents total energy expenditure during what kind of exercise?
submaximal, steady state exercise
as exercise intensity increases, what happens to VO2 and total energy expenditure
increases linearly
explain the procedure generally
students split 3 groups, three 6 minutes exercise bouts performed on bicycle ergometer or treadmill at three incremental intensities w 5 min break in between; one student in each group performs all three exercise bouts
how to determine kp needed to reach a certain power output (watts) at 60 rpm
power (watts) = rpm x kp
