Chapter 5: Energy Expenditure and Fatigue Flashcards
What is the substrate metabolism efficiency?
substrate energy
What is the percentage of substrate energy for ATP?
40%
What is the percentage of substrate energy for heat?
60%
heat production increases with what production?
energy
how can heat production increase with energy production?
- can be measured in a calorimeter
- water flows through walls
- body temperature increases water temperature
What are the Pros for measuring energy expenditure: direct calorimetry?
- accurate over time
- good for resting metabolic measurements
What are the Cons for measuring energy expenditure: direct calorimetry?
- expensive, slow
- exercise equipment adds extra heat
- sweat creates errors in measurements
- not practical or accurate for exercise
In indirect calorimetry, What is estimated total body energy expenditure based on?
O2 and CO2 produced
What does indirect calorimetry measure?
respiratory and gas concentrations
What is indirect calorimetry only accurate for?
steady-state oxidative metabolism
For indirect calorimetry, older methods of analysis are accurate but what?
slow
For indirect calorimetry, new methods are faster but what?
expensice
What does VO2 stand for?
volume of oxygen
What does VCO2 stand for?
volume of carbon dioxide
Explain VO2: volume of O2 consumed per minute.
- rate O2 consumption
- volume of inspired O2- volume of expired O2
Explain VCO2: volume of CO2 consumed per minute.
- rate CO2 consumption
- volume of expired CO2- volume of inspired CO2
What are the 6 calculations of VO2 and VCO2?
- volume of inspired air (Vi)
- volume of expired air (Ve)
- fraction of O2 in inspired air (FiO2)
- fraction of CO2 in inspired air (FiCO2)
- fraction of O2 in expired air (FeO2)
- fraction of CO2 in expired air (FeCO2)
What is the formula for oxygen consumption?
VO2= (Vi x FiO2) - (Ve x FeO2)
What is the formula for Carbon Dioxide produced?
VCO2= (Ve x FeCO2) - (Vi x FiCO2)
What are the oxygen consumption and carbon dioxide equations based on?
inspired volume= expired air volume
During Haldane Transformation, V of inspired O2 may not equal what?
V of expired CO2
During Haldane Transformation, V of inspired N2 equals what?
V of expired N2
Explain the Haldane Transformation.
- allows V of inspired air (unknown) to be directly calculated from V of expired air (known)
- based on constancy of N2 volumes
During Haldane Transformation, we measure concentration of O2 and CO2 in expired air why?
to calculate FeN2
FeN2= 1 - (FeO2 + FeCO2)
What is the SIMPLIFIED equation of Haldane Transformation?
VO2= (Ve) x {[1- (FeO2 + FeCO2)] x 0.265 - FeO2}
In the end of Haldane transformation, BTPS (body temperature, current atmospheric pressure, saturated with water vapor) is converted to what?
STPD ( standard temp (0degC) & pressure (760 mmHg), dry equivalent
During Respiratory Exchange Rate, explain the O2 usage.
O2 usage during metabolism depends on type of fuel being oxidized
- more carbon atoms in molecule = more O2 needed
- glucose (C6H12O6) < palmitic acid (C16H32O2)
Explain Respiratory Exchange Ratio (RER).
- ratio between rates of CO2 production, O2 usage
- allow to determine what % is energy coming from fat and carbs
What is the equation for RER?
RER= VCO2/ VO2
What requires more O2: Fat or Carbs?
FAT
What happens to fat and carbs if the intensity is increased?
fat decreases and carbs increases
1 liter of O2 equals to how many kcal?
5
What is metabolic rate?
Rate of energy use by body
At rest, RER =?
0.8
At rest Metabolic rate=?
2000 kcla/day
At rest VO2=?
0.3 l/min
RER for 1 molecule glucose=?
1.0
RER for 1 molecule pamitic acid =?
0.70
What is basal metabolic rate?
rate of energy expenditure at rest
What are the conditions to get BMR?
in supine position
thermoneutral environment
after 8 h sleep and 12 h fasting
What is the minimum energy required for living?
BMR
What is BMR related to?
fat free mass
What is BMR affected by?
body surface area, age, stress, hormones, body temperature
high muscle mass = ________ BMR
high
Are there any conditions/positions to get RER?
no
What does total daily metabolic activity include?
includes normal daily activities
normal range: 1800 to 3000 kcal/day
for athletes: up to 10,0000 kcla/day
What is VO2 max?
point at which O2 consumption doesn’t increase with further increase in intensity
What is the best single measurement of aerobic fitness?
VO2 max
T/F: VO2 max is the best predictor of endurance performance
false (it’s not)
When does VO2 max plateau?
after 8 to 12 weeks training
T/F: More training allows athlete to compete at higher percentage of VO2max
T
What is the unit of measurement for VO2 max?
L/min
What is VO2 max suitable for?
non-weight-bearing activities
T/F: VO2 max is more accurate comparison for different body sizes
T
T/F: No activity 100% aerobic or anaerobic
T
Estimates of anaerobic effort involve?
Excess post-exercise O2 consumption (EPOC)
Lactate threshold
When does O2 demand become > O2 consumed in early exercise?
body incurs O2 deficit
O2 required - O2 cosumed
Occurs when anaerobic pathways used for ATP production
When does O2 consumed > O2 demand in early recovery
?
Excess post- exercise O2 consumption (EPOC)
Replenishes ATP/PCr stores, converts lactate to glycogen
Replenishes hemo/myoglobin
clears CO2
EPOC is greater after high intense exercise: T/F
T
What is lactate threshold?
point at which blood lactate accumulation increase markedly
What is lactate threshold expressed as?
percentage of VO2max
T/F: lactate production rate > lactate clearance rate
T
Lactate threshold is a good indicator of?
potential for endurance exercise
Lactate threshold is an interaction of?
aerobic and anaerobic systems
Lactated accumulation leads to?
fatigue
T/F: higher lactate threshold = higher sustained exercise
T
T/F: intensity = better endurance performance
T
T/F: For two athletes with same VO2max, higher lactate threshold CANNOT predict better performance
F (IT CAN)
What are some other imperfect but accepted methods to measure anaerobic capacity?
maximal accumulated O2 deficit
Wingate Anaerobic test
Critical power test
T/F: As athletes become more skilled, use less energy for given pace
T
T/F: Why do athletes become more skilled, use less energy for given pace?
body becomes more efficient with practice
T/F: Economy of effort increases with distance of race
T
T/F: Practice leads to better economy of movement (form)
T
Energy of effort stays the same with type of exercise (running vs. swimming)
T
Energy Expenditure varies with ?
type and intensity of activity
Where is energy expenditure calculated from?
VO2 , expressed in kcal/min
Energy expenditure ignores anaerobix aspects, EPOC:
T/F
T
Daily expenditure depends on?
activity level
inherent body factors ( age, sex, size, weight, FFM)
Energy expenditure: successful endurance athletes depends on?
high VO2max
high lactate threshold
high economy of effort
high percentage of type I muscle fibers
What are the causes of fatigue?
Substrate Depletion
Accumulation of lactic acid and H+
Neuromuscular fatigue
What falls under substrate depletion?
creatine phosphate (CP) depletion glycogen depletion
What falls under accumulation of lactic acid and H+?
anaerobic activities
the H+ generated by lactic acid decreases muscle pH and impairs the cellular processes of energy production and muscle contraction
What is neuromuscular fatigue?
neural transmission
CNS
