Exercise Physiology Chapter 5

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Measurement of the body's heat production to estimate energy expenditure
Direct Calorimetry
This calculates energy expenditure from the ratio of CO2 produced to O2 consumed
Indirect Calorimetry
Amount of O2 and CO2 exchanged in lungs =?
The rate of usage and release by the body tissues
Substrate metabolism efficiency
40% of substrate efficiency =?
60% of substrate efficiency =?
40- ATP
60- Heat
Heat production increases with what?
Energy production
How can heat production be measured? (2)
1. Calorimeter
2. How much one is sweating
Pros of Measuring Direct Calorimetry (2)
1. Accurate over time
2. Good for resting metabolic measurements
In more depth what does indirect calorimetry measure & what is it only accurate for?
Measures respiratory gas concentrations but it is only accurate for steady state oxidative metabolism
Respiratory Gas exchange
Difference btw inspired and expired air/ how much 02 and CO2 were used
VO2
volume of oxygen consumed per minute
VCO2
volume of carbon dioxide consumed per minute
How to find VO2 and VCO2
VO2- volume of inspired O2- volume of expired O2
VCO2- Volume of Expired CO2- volume of inspired CO2
Haldane Transformation
Allows Volume of inspired air (unkown) to be directly calculated from the volume of expired air (known)
What is the Haldane Transformation based off of
consistency of Nitrogen volumes
Three gases that make up inspired air and their percentages
Oxygen-20.93%
CO2-.04%
N2- 79.03%
T/F: O2 usage during metabolism depends on the type of fuel being oxidized
True
The respiratory exchange ratio measures
ratio between O2 Usage and CO2 production
With the RER if carbon is more present what is needed?
More O2 to balance the ratio out
RER for 1 molecule of glucose=
1
RER for 1 molecule of palmitic acid=
.7
Indirect Calorimetry Limitation: (4)
1. CO2 production may not equal CO2 exhalation
2. RER inaccurate for protein oxidation
3. RER near 1.0 may be inaccurate when lactate buildup increases CO2 exhalation
4. Gluconeogenesis produces RER <.7
RER at Rest:
.78-.8
RER for oxidation of fat:
.7
RER for oxidation of CHO:
1
Metabolic Rate=
Rate of energy use by body
What is metabolic rate based on?
Whole body O2 consumption and corresponding caloric equivalent
At rest, metabolic rate is about:
2,000 kcal/day
Basal Metabolic Rate
Rate of energy expenditure at rest
What factors effect the basal metabolic rate's minimum energy requirement for living? (6)
1. Fat free mass
2. Body surface area
3. Age
4. Stress
5. Hormones
6. Body Temperature
How much O2 does a person consume per hour and day at rest?
Hour: .3L
Day: 432L
Caloric Expenditure Formula:
Kcal/day= L O2/ Day X Kcal used/ L of O2
Resting Metabolic Rate
Similar to BMR without stringent standardized conditions
Normal Resting Metabolic Range:
1,200-2,400 kcal/day
Total Daily Metabolic Activity
Includes normal daily activities
Normal Total Daily Metabolic Activity:
1,800- 3,000 kcal/day
Competitive Athlete Normal Daily Metabolic Activity:
up to 10,000 kcal/day
Factors Affecting RMR: (4)
1. Age
2. Body Temp
3. Physiological Stress
4. Hormones
T/F: Metabolic rate decreases with exercise intensity.
False, increases
During constant work rate, Vo2:
Increases from resting state to a steady-state within 1-2 mins
VO2 Max (3)
1. The maximal capacity for O2 consumption by the body during maximal exertion
2. Best single measurement of aerobic fitness
3. Not the best predictor of endurance performance
When does VO2 max plateau?
After 8-12 weeks of training
What is VO2 max expressed as?
L/min
Why is Vo2 max different in untrained young men and untrained you women? (2)
1. Women have less FFM
2. Women have less hemoglobin
T/F: No activity is 100% aerobic or anaerobic.
True
Best estimates of anaerobic effort: (2)
1. Excess post exercise o2 consumption (EPOC)
2. Lactate threshold
Oxygen Deficit:
The difference between o2 required for a exercise intensity and the actual o2 consumed
During early exercise:
o2 demand > o2 consumed
During Early recovery:
o2 consumed > o2 demand
Lactate Threshold
Point at which blood lactate production exceeds body's ability to clear or remove lactate
How is Lactate Threshold usually expressed?
As a percentage of Vo2 max
Lactate Accumulation leads to:
Fatigue
What is predictor of better performance for 2 athletes with the same Vo2 max?
Higher lactate threshold
Acceptable ways to measure anaerobic capacity: (3)
1. Maximal accumulated o2 deficit
2. Wingate test
3. Critical power test
Economy of Effort
The more skilled the athlete, the less energy used; Independent of Vo2 max; body learns energy economy with practice (form)
4 Things Successful Endurance Athletes have:
1. High Vo2 max
2. High lactate threshold
3. High economy of effort
4. High % of type 1 muscle fibers
Fatigue: (3)
1. Decreases in muscular performance with continued effort, with tiredness
2. Failure to maintain power output at a given intensity
3. Reversible by rest
What are the 3 Complex phenomenon factors in getting fatigue?
1. Type & intensity of workout
2. Muscle fiber type
3. Training status & diet
4 Major Cause of Fatigue
1. Inadequate energy delivery/metabolism
2. Accumulation of metabolic by products
3. Failure of muscle contractile mechanism
4. Altered neural control of muscle contraction
How is glycogen depletion different in activity specific exercise? (2)
1. Specific muscles deplete fastest
2. Activity specific muscles are the earliest recruited and longest lasting
Glycogen Depletion and Blood Glucose: (2)
1. Muscle glycogen is insufficient for prolonged exercise
2. Liver glycogen puts glucose in blood
Muscle glycogen depletion + hypoglycemia=
Fatigue
What helps maintain a certain rate of muscle glycogen? (2)
1. NADH in Krebs Cycle
2. ETC activity
Glycogen depletion leads to an increase in what?
FFA metabolism
Metabolic By-Products of Fatique: (4)
1. Pi
2. Heat
3. Lactic acid
4. H+ Lactic acid
Heat alters what? (3)
1. Metabolic rate
2. Carb utilization rate
3. Glycogen depletion rate
High muscle temp may do what?
Impair muscle function
Time exhaustion longest:
11 degrees celsius
Time to exhaustion shortest:
31 degrees celsius
What can prolong exercise?
Muscle cooling
If lactic acid is not cleared immediately it converts to:
H+ lactic acid
H+ Lactic Acid causes
Decrease in muscle pH
Buffers (2)
1. Minimize pH drop
2. Helps Cells survive but not function well
When can lactic acid not be bad? (2)
1. If production levels = clearance levels
2. If the lactic acid is used as a source of fuel
How is Lactic Acid used as fuel?
Converted to glucose through gluconeogenesis in the liver
Muscle activation is prevented by what?
Failure at neuromuscular junctions
Fatigue inhibits what?
Ca2+ release from sarcoplasmic reticulum
How does the CNS limit performance?
As a protective mechanism