Term
| Measurement of oxygen consumption (VO2) |
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Definition
Ability to Deliver & Use Oxygen
Expressed 2 ways-
- Liters per minute (L/min) (Absolute VO2)
- ml per kg of body weight per minute (ml/kg/min)(Relative VO2)
the average is 42-45 ml/per min
endurance runner is at least 75-80 ml/min |
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Term
| Energy Requirements at Rest |
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Definition
Almost 100% of ATP produced by aerobic metabolism
Blood lactate levels are low (<1.0 mmol/L)
Resting O2 consumption (70 kg adult):
0.25 L/min (absolute VO2)
3.5 ml/kg/min (relative VO2) - average base on body weight. |
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Term
| Metabolic Equivalents (MET) |
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Definition
The expression of energy cost for activities in a simple unit.
For the masses much like BMI.
Energy cost of exercise can be expressed in MET.
It is equal to 3.5 ml/kg/min VO2 at resting level
- 1 MET = 3.5 ml/kg/min |
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Term
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Definition
1)VO2max – maximal rate to transport and use oxygen.
2)A maximal oxygen consumption (VO2max) test requires that the participant use maximal effort in performing physical work to exhaustion by using bike or treadmill.
3)The test begins with a light workload and progresses, with increases every 2-3 minutes, to a workload that the participant can no longer sustain.
4)Oxygen uptake increases linearly until VO2max is reached
No further increase in VO2 with increasing work rate
3)Considered by many to be most valid measurement of cardiovascular fitness
measuring VO2 max is to exercise until exhaustion |
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Term
Test
Measuring VO2max
The most relevant criteria are: |
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Definition
1)the plateau of oxygen consumption
2. the attainment of respiratory exchange ratios (RER = CO2/O2) of 1:1 or 1:15
note when ratio is 1.15 the person usually reach the maximal VO2.
1.0 is the resting lactate concentration.
higher.
3. the attainment of age-predicted HR
4. the exhaustion of the participant stop exercise
5. blood [La] > 8.0 mM/L
6. lactate concentration is greater than 8.0 or more |
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Term
| Rest-to-Exercise Transitions |
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Definition
1)ATP production increases immediately
2)Oxygen uptake increases rapidly
-Reaches steady state within 1–4 minutes
-After steady state is reached, ATP requirement is met through aerobic ATP production
3)Initial ATP production through anaerobic pathways
ATP-PCr system
Fast Glycolysis
4)Oxygen deficit
Delay in oxygen uptake at the beginning of exercise |
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Term
The Oxygen Deficit
figure 4.1 |
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Definition
Lag in oxygen consumption
at the onset of exercise
- Oxygen deficit
ATP production at the onset of
exercise is maintained by:
- oxygen stores (O2 bound to
myoglobin)
- ATP-PC
- fast glycolysis
Note it usually take 4 or 5 minute to reach oxygen consumption, depends on exercise intensity. in the beginning our body borrow oxygen and after exercise our body repaid it during recovery. at the end of exercise our ATP decrease. |
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Term
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Definition
the difference between the total oxygen actually consumed during exercise and the total oxygen required (consumed) in steady-rate from the start of exercise.
As begin exercise, not producing enough O2 to do work.
Then, the body borrows on its energy reserves (credits). After exercise, the body tries to pay back those credits plus some interest. |
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Term
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Definition
As begin exercise, not producing enough O2 to do work:
(1) Accumulate Lactate
(2) This is the O2 deficit
(3) This will have to be paid back (metabolized later) |
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Term
| Comparison of Trained and Untrained Subjects |
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Definition
Trained subjects have a lower oxygen deficit
Better-developed aerobic bioenergetic capacity
Due to cardiovascular or muscular adaptations
Results in less production of lactic acid
trained reach steady state faster than untrained.
trained individual can use less , and fast glycolysis which produce less lactic acid. |
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Term
Rest-to-Exercise Transitions
In Summary |
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Definition
In the transition from rest to light or moderate exercise, oxygen uptake increases rapidly, generally reaching a steady state within one to four minutes.
The term oxygen deficit applies to the lag in oxygen uptake in the beginning of exercise.
The failure of oxygen uptake to increase instantly at the beginning of exercise suggests that anaerobic pathways contribute to the overall production on ATP early in exercise.
After a steady state is reached, the body’s ATP requirement is met via aerobic metabolism. |
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Term
| Excess Postexercise Oxygen Consumption (EPOC) |
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Definition
After exercise, O2 consumption does not return to resting levels immediately.
Then, the extra O2 consumed during recovery, above a resting baseline is called Excess Postexercise Oxygen Consumption (EPOC).
EPOC is also termed O2 debt.
Greater oxygen debt takes longer for VO2 level to return to resting value at 3.5/min |
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Term
Excess Post-Exercise Oxygen Consumption (EPOC)
Oxygen consumption remains elevated following exercise |
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Definition
-Classical term – oxygen debt
-Depends on intensity and duration of activity
.Rapid curve component (“Rapid” portion ) – steep decline
.Slow curve component (“Slow” portion) |
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Term
Oxygen Debt (EPOC)
(fast)
Rapid curve component |
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Definition
- Steep decline in O2 consumption
-Replenish ATP, PC, Oxygen stores.
our body try to store. |
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Term
Oxygen Debt (EPOC)
Slow curve component |
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Definition
-Slow decline in O2 consumption
-Elevated heart rate and breathing = energy need (maintain high to increase energy need)
-Elevated body temperature = metabolic rate
-Elevated epinephrine and norepinephrine = metabolic rate ( stress hormones maintain high)
-Conversion of lactic acid to glucose (gluconeogenesis)
-lactate removal |
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Term
| Oxygen Debt (EPOC) ( percentage) |
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Definition
70% lactate will oxidized by working muscle.
20% converted to glucose
10% converted to amino acid |
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Term
Factors contributing to Exercise Post-Exercise Oxygen Consumption
Elevated Hormones |
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Definition
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Term
Factors contributing to Exercise Post-Exercise Oxygen Consumption
Post- exercise elevation of HR and breathing |
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Definition
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Term
Factors contributing to Exercise Post-Exercise Oxygen Consumption
Elevated body temperature |
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Definition
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Term
Factors contributing to Exercise Post-Exercise Oxygen Consumption
Restoration of muscle and blood oxygen stores |
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Definition
| (Fast) Rapid curve component |
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Term
Factors contributing to Exercise Post-Exercise Oxygen Consumption
Lactate removal |
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Definition
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Term
Factors contributing to Exercise Post-Exercise Oxygen Consumption
Resynthesis of PC in muscle |
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Definition
| (Fast) Rapid curve component |
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Term
| EPOC is Greater Following Higher Intensity Exercise |
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Definition
.Higher body temperature
.Greater depletion of PC
.Greater blood concentrations of lactic acid
.Higher levels of blood epinephrine and norepinephrine |
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Term
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Definition
.During recovery, 4/5 of the lactate is oxidized and 1/5 is reconverted to glycogen.
.Because blood lactate does not decline immediately (a delay), Fast Curve of EPOC is NOT associated with a change in blood lactate (nothing to do with lactate metabolism).
.Slow Curve of EPOC coincides with the decline in blood lactate that is due to the reconverted of lactate to glycogen. |
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Term
| Metabolic Responses to Prolonged Exercise |
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Definition
Prolonged exercise (>10 minutes)
-ATP production primarily from aerobic metabolism
-Steady-state oxygen uptake can generally be maintained during submaximal exercise
Prolonged exercise in a hot/humid environment or at high intensity
-Upward drift in oxygen uptake over time
-Due to body temperature and rising epinephrine and norepinephrine |
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Term
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Definition
The point at which blood lactic acid rises systematically during incremental exercise
-Appears at ~50–60% VO2 max in untrained subjects
-At higher work rates (65–80% VO2 max) in trained subjects
Also called:
-Anaerobic threshold
-Onset of blood lactate accumulation (OBLA)
.Blood lactate levels reach 4 mmol/L |
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Term
| Explanations for the Lactate Threshold |
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Definition
.Low muscle oxygen (hypoxia)
.Accelerated glycolysis
-NADH produced faster than it is shuttled into mitochondria
-Excess NADH in cytoplasm converts pyruvic acid to lactic acid
.Recruitment of fast-twitch muscle fibers
-LDH isozyme in fast fibers promotes lactic acid formation
.Reduced rate of lactate removal from the blood |
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Term
| Factors affecting lactate appearance and disappearance |
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Definition
[La] = rate of appearance – rate of disappearance
--What affects appearance?
.Production and release
.Recruitment of fast twitch fibers
.LDH isoform
.Increased epinephrine
What affects disappearance?
.Rate of uptake into non-working muscles
.Oxidation by muscles, liver
-Blood flow |
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Term
| Practical Uses of the Lactate Threshold |
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Definition
.Prediction of performance
-Combined with VO2 max
.Planning training programs
-Marker of training intensity |
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Term
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Definition
70% - oxidized by other tissues
20% - converted to glycogen or glucose in liver (Cori Cycle)
10% - converted to amino acids |
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