Chapter 4 Flashcards
What is the oxygen deficit?
It is the lag of Oxygen uptake at the start of exercising. (the lack of o2)
How long does it take to reach steady state?
Depends on intensity. Trained people reach it faster than untrained people.
What is the oxygen debt?
The excess oxygen uptake above rest after exercise.
What does EPOC stand for?
Excess Post-exercise Oxygen Consumption
Why is the oxygen consumption elevated following exercise?
REEL PR: Resynthesis of PC in muscle
Lactate removal
Restoration of muscle and blood oxygen stores
Elevated body temp
Post-exercise elevation of HR and breathing
Elevated hormones
How does exercise intensity influence the oxygen debt? Why does it have this effect?
High intensity - slower and more oxygen debt that needs to be replaced
Low-intensity - faster and less oxygen debt that needs to be replaced. (think of running 400m vs. walking 400m)
What energy systems are being used during short duration, high intensity exercise?
Anaerobic sources (ATP-PC 1-5 sec, gylcolysis 5-6 sec) - gradual shift
What energy systems are being used during prolonged exercise?
Aerobic sources
Under what conditions might the oxygen cost rise during prolonged exercise?
Hot/Humid environments & Continuous exercise
What causes this drift in oxygen consumption?
Increased body temp & rising hormones
Define VO2 max.
Q (HR x SV) x a-v o2 diff. The maximal ability of the body to transport and utilize oxygen. (Maximum oxygen uptake)
What energy systems are used during a graded exercise test (incremental exercise)?
Both anaerobic and aerobic energy systems
What rises in the blood during incremental exercise? What type of rise does lactate follow?
Blood levels of lactate rise during incremental exercise in an exponential fashion.
What is the OBLA / lactate threshold?
The point at which there is a sudden rise in lactate. Onset of Blood Lactate Accumulation.
Lactate Accumulation is influenced by what two factors?
Rate of glycolysis to the ability to transport NADH to the mitochondria.
Rate of lactate removal from the blood.
BLOOD CONCENTRATION = Lactate entry - Lactate removal
Lactate entry - Lactate removal
At what exercise intensity does lactate rise for?
Trained Athletes: 65-85% VO2 max
Untrained Athletes: 50-60% VO2 max
What is the respiratory exchange ratio and how is it calculated?
VCO2/VO2
Estimates the % contribution of carbohydrates and fats. ( the ratio of CHO produced to the O2 consumed. ) REMEMBER LAB!
Under what respiratory condition must the RER be calculated?
When steady state has been reached.
The following fuels are being used at R values of:
- 0 - CHO 100%
- 85 - CHO 50% Fat 50%
- 70 - Fat 100%
What are the two main energy sources for the body?
- Fats
2. Carbohydrates
How much does protein contribute to the total energy pool during exercise?
Less than 2% , it plays a very minor role.
What two factors are the main determinants of substrate use?
- Intensity (CHO)
2. Duration (Fats)
At low intensities of exercise this fuel is primarily being used…
30% VO2 max, Fats
At high intensities of exercise this fuel is primarily being used…
70% VO2 max, CHO
Why does the body shift from fats to carbohydrates as the main energy source with increasing intensities?
- the recruitment of fast twitch fibers
- increases in epinephrine
- process rate capability of oxidative metabolism
As duration increases, the body relies more heavily on what energy source?
Fats
Why aren’t fats used as an immediate source of energy?
Lypolysis is a slow process.
An increase in fat metabolism occurs only after several minutes of exercise.
When do muscle glycogen stores begin to deplete?
After more than 2 hours
Why does muscle gylcogen depletion result in fatigue? And what does the saying “Fat burns in a CHO flame” mean?
- Depletion of available carbohydrate reduces the rate of glycolysis - concentration of pyruvate reduced in the muscle.
- Lowers the rate of aerobic production of ATP by reducing the number of krebs-cycle compounds
- When carbohydrate stores are depleted in the body, the rate at which fat is metabolised is also reduced.
Lactate is a metabolic waste product. Does lactate have any useful roles?
Acts as a buffer to H+ (acidity)
In what ways can we use lactate as a fuel source?
Cori cycle - Converts lactic acid back into gluecose in the liver.
Lactate Shuttle - Slows skeletal and cardiac muscle. Convert to pyruvate and then into Acetyl-CoA.
(Intracellular - processed through the cell)
(Cell-to-cell - come in from blood and processed through different cell)
