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124 Cards in this Set

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  • Back
6 Indications for exercise testing:
1. SOB on exertion
2. Determine functional capacity
3. Exercise-induced asthma
4. Max O2 consumption studies
5. Workers comp claims
6. Military assessment
What is the best measure of cardiovascular fitness?
O2 consumption studies
What is Recruitment?
The increase in functional alveolar-capillary units during exercise (increases perfusion of skeletal muscles)
What is minute ventilation made up of?
Alveolar + Deadspace ventilation
What % of the tidal volume goes to alveoli vs deadspace normally?
Alveoli = 60% of TV
Deadspace = 40%
What are the 2 ways by which the lungs physiologically respond to exercise?
-Increase tidal volume
-Increase breathing frequency
What is the pulmonary circulation's physiological responses to exercise?
To recruit more alveolar-cap functional units.
What is the heart's physiological response to exercise?
-Increase Stroke volume
-Increase heartrate
What is the peripheral circulation's physiological responses to exercise?
What is the active muscle's physiological responses to exercise?
Increase O2 and CO2 flow rates
Why does the need for oxygen increase during exercise?
Because the amount of ATP we normally have stored is pretty low and it takes O2 to make more.
What are 3 ways of making ATP?
1. Phosphocreatine breakdown
2. Glycogen metabolism
3. Glucose/FA/AA metabolism
How many hi-energy bonds are available in ATP?
How much time of exercise can we achieve based on our stored ATP levels?
Only enough for 2-3 sec
How much time of exercise can we achieve based on our stored ATP levels + Phosphocreatine??
8-10 sec
How long can we exercise based on our stored ATP levels + Phosphocreatine + Anaerobic glycogen metabolism?
1-2 min
How long can we exercise based on our stored ATP levels + Phosphocreatine + Anaerobic glycogen metabolism + Aerobic glu/AA/FA metabolism?
Longer than 2 min, and indefinetely as long as the source of Glu/FA/AA are available.
What is the byproduct of anaerobic metabolism?
What are the byproducts of aerobic metabolism?
CO2 + H2O + Urea
How does body metabolism change during exercise?
It increases significantly to provide the necessary ATP
How much does metabolism increase during a marathon?
As much as 200X
Where does anaerobic glycolysis occur?
In the cytoplasm
Where does aerobic metabolism of carbs occur?
In the mitochondrial TCA cycle
Where does FA beta oxidation occur?
In mitochondria
What is the net ATP yield of glycolysis?
2 pyruvic acid which can enter the next step, TCA cycle
What do the net reactions of the TCA cycle yield from 2 AcCoA?
-4 CO2
-16 H+
-2 CoA
-2 ATP
So how many H+ ions are formed by the metabolism of one glu from glycolysis + TCA cycle?
How many ATP can be formed from 24 protons?
34 ATP
How many ATP are formed from 1 glucose molecule?
38 ATP
How many moles of ATP are formed from 1 mole of glucose?
What type of fuel do we burn predominantly early in the first seconds of exercise?
What type of fuel do we burn predominantly as exercise proceeds over minutes to hours?
We burn fat primarily more than carbs
How does fuel utilization change in a high-fat diet?
Carb usage will switch over to fat usage much sooner, but exhaustion will occur much sooner too - 1 hr instead of 4
How does fuel utilization change in a high-carb diet?
Carb usage will remain at 100% much longer, and exhaustion won't occur until 4 hours of exercise.
What is the phosphagen system?
The system that uses our small stored amts of ATP plus phosphocreatine
What is the maximal rate of power generation achieved by the phosphagen system?
4 moles of ATP / minute
.. but it doesn't last long, only like 8-10 sec
What is the maximal rate of power generation achieved by the Glycogen-Lactate system?
2.5 moles of ATP / minute
What is the maximal rate of power generation achieved by the Aerobic system?
1 mole of ATP / minute
-but it lasts indefinetely as long as AA/FA/glucose are available
How do tidal volume and freq change during exercise?
Low intensity: TV increases more predominantly than freq
High intensity: Freq increases
What would alert you to a Ventilatory Limitation?
If breathing freq increased to higher than 55 breaths/min
What type of ventilatory limitation would have have an abnormally high breathing freq?
Restrictive defects
What is minute ventilation?
The amt of air either inspired or expired per minute
What is alveolar ventilation?
The amount of air that reaches the alveoli per minute.
What is the typical TV and freq for a 70 kg man?
TV = 500 ml
Freq = 12 breaths/min
What is the normal minute V?
500 x 12 = 6 L/min
What does tidal volume ventilate?
-Dead space
So how do you calculate alveolar ventilation?
VA = (TV - DS) x Freq
What is the typical ANATOMIC dead space volume? What doesn't this usually inclue?
154 mL
-Not normally including alveolar deadspace bc it's so small
So what is the typical alveolar ventilation value?
(500 - 154) x 12 = 4.15 L/min
As we increase our tidal volume and breathing freq during exercise, what happens to deadspace and alveolar ventilations?
-Deadspace ventilation unchanged
-Alveolar ventilation increases and MORE than even minute ventilation
How much deadspace volume is there per kilo of weight on avg?
About 2 mL deadspace/kilogram
So for the average 70 kg man he has how much deadspace?
~140 ml (not so far off from 154 mL)
What happens to the distribution of ventilation if there is an obstructive impairment?
Alveolar Deadspace is increased, so as ventilation increases during exercise, it won't increase as much in the alveoli.
So what increases more significantly at low intensity exercise; TV or freq?

What contributes to the increase in minute ventilation at high intensity exercise?
Tidal volume at low intensity

Breathing freq at high intensity
What is O2 consumption? normal value?
The amount of oxygen used by our cells per minute - normally 0.25 L/min at rest
What is O2 extraction?
The amount of O2 removed per 100 mL of blood
How do we evaluate O2 extraction?
By looking at the arterial-venous difference
How much is or normal resting oxygen store?
2 L
What makes up the 2 L of stored oxygen we normally have?
-0.25 L dissolved
-0.30 L on myoglobin
-0.5 L in the lungs
-1.0 L on hemoglobin
What is oxygen debt?
The additional o2 consumption that occurs after strenuous exercise is done to restore the oxygen stores and ATP levels
What is the purpose of O2 debt consumption?
To repay the O2 stores and replenish phosphagen and lactate systems.
What is the "Cost of Ventilation"?
The portion of total O2 consumption utilized by the respiratory muscles
How is oxygen consumption calculated? (VO2)
(Vi x FiO2) - (Ve x FeO2)
What is the usual fraction of O2 that we exhale?
Not lower than 16%
What is the usual fraction of O2 that we inhale?
How are Vi and Ve related?
Usually the expiration to inspiration ratio is 1:2
How is Carbon dioxide production calculated?
(Ve x FeCO2) - (Vi x FiCO2)
What is the normal fraction of CO2 inhaled?
Close to zero
What is the normal fraction of CO2 exhaled?
About 4-5%
And again; the O2 consumption is defined as:
The amt of oxygen our cells use per minute
What is the normal value for O2 consumption at rest? At strenuous exercise?
-250 mL/min at rest
-5000 mL/min at strenuous ex
What is the cost of ventilation (used by resp muscles) at rest? At strenuous exercise?
Rest: 2-5% of O2 ventilation
Strenuous Ex: >30% of VO2
What is another name for the Cost of Ventilation?
Respiratory Steal Phenomenon
What is it that normally causes us to max out in our exercise capacity?
Heart rate
When does the Respiratory Steal limit exercise?
In patients with obstructive impairments - COPD/emphesyma
How much does oxygen extraction increase as exercise intensity increases?
Up to 3-4 X resting levels
What is the resting level of oxygen extraction?
4.5 ml/100 ml of blood
What is max oxygen extraction?
About 14 ml/100 ml of blood
What limits oxygen extraction in normal people?
Cardiac output - it can go up pretty significantly but only up to a point
What happens when CO and oxygen extraction plateau?
Ventilation continues to increase, but now it is disproportionate to the O2 uptake; the purpose is to get rid of CO2 byproduct from lactate buffering.
What do we call the point at which the body starts making lactate?
AT - anaerobic threshold
What causes CO to increase at
-low intensity exercise
-high intensity exercise
Low: increased stroke volume
High: increased heartrate (due to increased breathing freq)
What is the normal value of O2 consumption?
~0.25 L/min
How much can O2 consumption increase during maximal exercise?
To 20X normal - almost 5L/min
How do we measure O2 consumption?
By measuring O2 uptake
Does O2 uptake always equal O2 consumption? Why/why not?
No - beause O2 consumption is referring to cellular uptake; we can only measure uptake at the alveolar level and if one is hyperventilating it's artifact.
What happens to O2 uptake after 4 minutes of very heavy exercise?
O2 uptake remains elevated even for 45 minutes.
Why does O2 remain elevated after stopping exercise in the
-first 4 minutes after stopping
-minutes 8-45 after stopping
Initially: to pay back the O2 debt to phosphocreatine, aerobic metabolism, and stored O2 debt
Then: to pay back the lactate O2 debt
How many liters of O2 are contained in the Alactic acid debt? Lactate debt?
Alactate = 3.5 L
Lactate = 8 liters
What happens to the body's pH as lactate is produced?
It drops from 7.4 to 7.19
What is the normal level of lactate in the body?
~1-2 mEq/L
How much does lactate increase during very heavy exercise for 8 minutes or so?
Up to like 12 mEq/L!
What is the RQ?
Respiratory Quotient
The ratio of CO2 production to O2 usage
What is the use of the RQ?
To estimate fat and carb utilization
What is the RQ if you're burning pure glucose?
What is the RQ for FA?
What is the RQ for protein?
What is the normal RQ?
Between .7 and .8
What happens to CO2 production and O2 uptake as exercise intensity increases?
Both increases proportionately until the point at which O2 consumption can't increase anymore; then CO2 will increase more.
Why does CO2 start to increase more as O2 consumption maxes?
Because lactate starts to be produced, and CO2 is a byproduct of lactate production.
How do you know if you've hit the anaerobic threshold?
The RQ exceeds 1
What is RER?
Resp Exchange Ratio - the ratio of CO2 output to O2 uptake
How is the RER related to the RQ?
They are equal in homeostasis
RER>RQ in hyperventilation
RER<RQ in hypoventilation
If a patient is hyperventilating and the RER is >1, does that mean their RQ is >1?
No; bc it's being measured at the alveolar level, not cellular.
4 other names for the Anaerobic Threshold:
-Lactate threshold
-Lactic Acid threshold
-Gas exchange threshold
-Ventilatory threshold
What is the Anaerobic Threshold?
The point of exercise intensity and duration where arterial lactate increases and causes a metabolic acidosis
Where is the AT?
At 50-60% of maximal exercise capacity
How much will lactate levels increase if a person has hit their AT?
By about 4 mEq
What is the O2 Ventilatory Equivalent?
The ratio of Total ventilation (minute vent.) to O2 consumption (uptake)
What is the normal O2 ventilatory equivalent during moderate exercise?
What happens to the O2 Vent Equivalent as exercise intensity goes up?
The VE goes up but only to 100:4 which is like 25:1
So how much does total ventilation have to increase for every extra liter of O2 consumed by the cells during exercise?
By 20 L (ratio of 20:1)
If the VE is like 80:1 what does that tell you?
The person is hyperventilating - their ventilation is greatly increased but not their O2 consumption.
What would a VE of 10:1 tell you?
That the person has increased ventilation to only 40 L/min, but significantly increased their O2 consumption (4 L/min) so their VE is more efficient
What is the resting VE for CO2?
A little higher than that for O2
Where does the VE for O2 deviate from 20:1 to be more like 25:1?
At the anaerobic threshold - because CO2 starts to be increased more so you have to increase Ventilation to blow off the CO2 byproduct of lactacte buffering
Look at the powerpoint you made for this
What happens to the VE for O2 after exercise?
It remains elevated as the body stores O2 and gets rid of CO2 to pay back the oxygen debt - but no longer consuming O2 by muscles so the ratio is high
What happens to the body's MAP during exercise?
It increases somewhat
What happens to diastolic BP during exercise?
It doesn't increase much
What happens to systolic BP during exercise?
It increases significantly!
So why does MAP increase somewhat during exercise?
Because of the widening of the pulse pressures
What happens to TPR during exercise?
It drops to increase perfusion
What is the magic number for exercise physiology?
50-60% max exercise capacity - that's the anaerobic threshold, when everything changes.