79. & 80. Exercise Physiology I/ii

Front 1

6 Indications for exercise testing:

Back 1

1. SOB on exertion
2. Determine functional capacity
3. Exercise-induced asthma
4. Max O2 consumption studies
5. Workers comp claims
6. Military assessment

Front 2

What is the best measure of cardiovascular fitness?

Back 2

O2 consumption studies

Front 3

What is Recruitment?

Back 3

The increase in functional alveolar-capillary units during exercise (increases perfusion of skeletal muscles)

Front 4

What is minute ventilation made up of?

Back 4

Alveolar + Deadspace ventilation

Front 5

What % of the tidal volume goes to alveoli vs deadspace normally?

Back 5

Alveoli = 60% of TV
Deadspace = 40%

Front 6

What are the 2 ways by which the lungs physiologically respond to exercise?

Back 6

-Increase tidal volume
-Increase breathing frequency

Front 7

What is the pulmonary circulation's physiological responses to exercise?

Back 7

To recruit more alveolar-cap functional units.

Front 8

What is the heart's physiological response to exercise?

Back 8

-Increase Stroke volume
-Increase heartrate

Front 9

What is the peripheral circulation's physiological responses to exercise?

Back 9

Dilation

Front 10

What is the active muscle's physiological responses to exercise?

Back 10

Increase O2 and CO2 flow rates

Front 11

Why does the need for oxygen increase during exercise?

Back 11

Because the amount of ATP we normally have stored is pretty low and it takes O2 to make more.

Front 12

What are 3 ways of making ATP?

Back 12

1. Phosphocreatine breakdown
2. Glycogen metabolism
3. Glucose/FA/AA metabolism

Front 13

How many hi-energy bonds are available in ATP?

Back 13

2

Front 14

How much time of exercise can we achieve based on our stored ATP levels?

Back 14

Only enough for 2-3 sec

Front 15

How much time of exercise can we achieve based on our stored ATP levels + Phosphocreatine??

Back 15

8-10 sec

Front 16

How long can we exercise based on our stored ATP levels + Phosphocreatine + Anaerobic glycogen metabolism?

Back 16

1-2 min

Front 17

How long can we exercise based on our stored ATP levels + Phosphocreatine + Anaerobic glycogen metabolism + Aerobic glu/AA/FA metabolism?

Back 17

Longer than 2 min, and indefinetely as long as the source of Glu/FA/AA are available.

Front 18

What is the byproduct of anaerobic metabolism?

Back 18

Lactate

Front 19

What are the byproducts of aerobic metabolism?

Back 19

CO2 + H2O + Urea

Front 20

How does body metabolism change during exercise?

Back 20

It increases significantly to provide the necessary ATP

Front 21

How much does metabolism increase during a marathon?

Back 21

As much as 200X

Front 22

Where does anaerobic glycolysis occur?

Back 22

In the cytoplasm

Front 23

Where does aerobic metabolism of carbs occur?

Back 23

In the mitochondrial TCA cycle

Front 24

Where does FA beta oxidation occur?

Back 24

In mitochondria

Front 25

What is the net ATP yield of glycolysis?

Back 25

2 ATP
2 pyruvic acid which can enter the next step, TCA cycle

Front 26

What do the net reactions of the TCA cycle yield from 2 AcCoA?

Back 26

-4 CO2
-16 H+
-2 CoA
-2 ATP

Front 27

So how many H+ ions are formed by the metabolism of one glu from glycolysis + TCA cycle?

Back 27

24

Front 28

How many ATP can be formed from 24 protons?

Back 28

34 ATP

Front 29

How many ATP are formed from 1 glucose molecule?

Back 29

38 ATP

Front 30

How many moles of ATP are formed from 1 mole of glucose?

Back 30

38

Front 31

What type of fuel do we burn predominantly early in the first seconds of exercise?

Back 31

Carbs

Front 32

What type of fuel do we burn predominantly as exercise proceeds over minutes to hours?

Back 32

We burn fat primarily more than carbs

Front 33

How does fuel utilization change in a high-fat diet?

Back 33

Carb usage will switch over to fat usage much sooner, but exhaustion will occur much sooner too - 1 hr instead of 4

Front 34

How does fuel utilization change in a high-carb diet?

Back 34

Carb usage will remain at 100% much longer, and exhaustion won't occur until 4 hours of exercise.

Front 35

What is the phosphagen system?

Back 35

The system that uses our small stored amts of ATP plus phosphocreatine

Front 36

What is the maximal rate of power generation achieved by the phosphagen system?

Back 36

4 moles of ATP / minute
.. but it doesn't last long, only like 8-10 sec

Front 37

What is the maximal rate of power generation achieved by the Glycogen-Lactate system?

Back 37

2.5 moles of ATP / minute

Front 38

What is the maximal rate of power generation achieved by the Aerobic system?

Back 38

1 mole of ATP / minute
-but it lasts indefinetely as long as AA/FA/glucose are available

Front 39

How do tidal volume and freq change during exercise?

Back 39

Low intensity: TV increases more predominantly than freq
High intensity: Freq increases

Front 40

What would alert you to a Ventilatory Limitation?

Back 40

If breathing freq increased to higher than 55 breaths/min

Front 41

What type of ventilatory limitation would have have an abnormally high breathing freq?

Back 41

Restrictive defects

Front 42

What is minute ventilation?

Back 42

The amt of air either inspired or expired per minute

Front 43

What is alveolar ventilation?

Back 43

The amount of air that reaches the alveoli per minute.

Front 44

What is the typical TV and freq for a 70 kg man?

Back 44

TV = 500 ml
Freq = 12 breaths/min

Front 45

What is the normal minute V?

Back 45

500 x 12 = 6 L/min

Front 46

What does tidal volume ventilate?

Back 46

-Alveoli
-Dead space

Front 47

So how do you calculate alveolar ventilation?

Back 47

VA = (TV - DS) x Freq

Front 48

What is the typical ANATOMIC dead space volume? What doesn't this usually inclue?

Back 48

154 mL
-Not normally including alveolar deadspace bc it's so small

Front 49

So what is the typical alveolar ventilation value?

Back 49

(500 - 154) x 12 = 4.15 L/min

Front 50

As we increase our tidal volume and breathing freq during exercise, what happens to deadspace and alveolar ventilations?

Back 50

-Deadspace ventilation unchanged
-Alveolar ventilation increases and MORE than even minute ventilation

Front 51

How much deadspace volume is there per kilo of weight on avg?

Back 51

About 2 mL deadspace/kilogram

Front 52

So for the average 70 kg man he has how much deadspace?

Back 52

~140 ml (not so far off from 154 mL)

Front 53

What happens to the distribution of ventilation if there is an obstructive impairment?

Back 53

Alveolar Deadspace is increased, so as ventilation increases during exercise, it won't increase as much in the alveoli.

Front 54

So what increases more significantly at low intensity exercise; TV or freq?

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

Back 54

Tidal volume at low intensity


Breathing freq at high intensity

Front 55

What is O2 consumption? normal value?

Back 55

The amount of oxygen used by our cells per minute - normally 0.25 L/min at rest

Front 56

What is O2 extraction?

Back 56

The amount of O2 removed per 100 mL of blood

Front 57

How do we evaluate O2 extraction?

Back 57

By looking at the arterial-venous difference

Front 58

How much is or normal resting oxygen store?

Back 58

2 L

Front 59

What makes up the 2 L of stored oxygen we normally have?

Back 59

-0.25 L dissolved
-0.30 L on myoglobin
-0.5 L in the lungs
-1.0 L on hemoglobin

Front 60

What is oxygen debt?

Back 60

The additional o2 consumption that occurs after strenuous exercise is done to restore the oxygen stores and ATP levels

Front 61

What is the purpose of O2 debt consumption?

Back 61

To repay the O2 stores and replenish phosphagen and lactate systems.

Front 62

What is the "Cost of Ventilation"?

Back 62

The portion of total O2 consumption utilized by the respiratory muscles

Front 63

How is oxygen consumption calculated? (VO2)

Back 63

(Vi x FiO2) - (Ve x FeO2)

Front 64

What is the usual fraction of O2 that we exhale?

Back 64

Not lower than 16%

Front 65

What is the usual fraction of O2 that we inhale?

Back 65

21%

Front 66

How are Vi and Ve related?

Back 66

Usually the expiration to inspiration ratio is 1:2

Front 67

How is Carbon dioxide production calculated?

Back 67

(Ve x FeCO2) - (Vi x FiCO2)

Front 68

What is the normal fraction of CO2 inhaled?

Back 68

Close to zero

Front 69

What is the normal fraction of CO2 exhaled?

Back 69

About 4-5%

Front 70

And again; the O2 consumption is defined as:

Back 70

The amt of oxygen our cells use per minute

Front 71

What is the normal value for O2 consumption at rest? At strenuous exercise?

Back 71

-250 mL/min at rest
-5000 mL/min at strenuous ex

Front 72

What is the cost of ventilation (used by resp muscles) at rest? At strenuous exercise?

Back 72

Rest: 2-5% of O2 ventilation
Strenuous Ex: >30% of VO2

Front 73

What is another name for the Cost of Ventilation?

Back 73

Respiratory Steal Phenomenon

Front 74

What is it that normally causes us to max out in our exercise capacity?

Back 74

Heart rate

Front 75

When does the Respiratory Steal limit exercise?

Back 75

In patients with obstructive impairments - COPD/emphesyma

Front 76

How much does oxygen extraction increase as exercise intensity increases?

Back 76

Up to 3-4 X resting levels

Front 77

What is the resting level of oxygen extraction?

Back 77

4.5 ml/100 ml of blood

Front 78

What is max oxygen extraction?

Back 78

About 14 ml/100 ml of blood

Front 79

What limits oxygen extraction in normal people?

Back 79

Cardiac output - it can go up pretty significantly but only up to a point

Front 80

What happens when CO and oxygen extraction plateau?

Back 80

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.

Front 81

What do we call the point at which the body starts making lactate?

Back 81

AT - anaerobic threshold

Front 82

What causes CO to increase at
-low intensity exercise
-high intensity exercise

Back 82

Low: increased stroke volume
High: increased heartrate (due to increased breathing freq)

Front 83

What is the normal value of O2 consumption?

Back 83

~0.25 L/min

Front 84

How much can O2 consumption increase during maximal exercise?

Back 84

To 20X normal - almost 5L/min

Front 85

How do we measure O2 consumption?

Back 85

By measuring O2 uptake

Front 86

Does O2 uptake always equal O2 consumption? Why/why not?

Back 86

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.

Front 87

What happens to O2 uptake after 4 minutes of very heavy exercise?

Back 87

O2 uptake remains elevated even for 45 minutes.

Front 88

Why does O2 remain elevated after stopping exercise in the
-first 4 minutes after stopping
-minutes 8-45 after stopping

Back 88

Initially: to pay back the O2 debt to phosphocreatine, aerobic metabolism, and stored O2 debt
Then: to pay back the lactate O2 debt

Front 89

How many liters of O2 are contained in the Alactic acid debt? Lactate debt?

Back 89

Alactate = 3.5 L
Lactate = 8 liters

Front 90

What happens to the body's pH as lactate is produced?

Back 90

It drops from 7.4 to 7.19

Front 91

What is the normal level of lactate in the body?

Back 91

~1-2 mEq/L

Front 92

How much does lactate increase during very heavy exercise for 8 minutes or so?

Back 92

Up to like 12 mEq/L!

Front 93

What is the RQ?

Back 93

Respiratory Quotient
The ratio of CO2 production to O2 usage

Front 94

What is the use of the RQ?

Back 94

To estimate fat and carb utilization

Front 95

What is the RQ if you're burning pure glucose?

Back 95

1

Front 96

What is the RQ for FA?

Back 96

.8

Front 97

What is the RQ for protein?

Back 97

.7

Front 98

What is the normal RQ?

Back 98

Between .7 and .8

Front 99

What happens to CO2 production and O2 uptake as exercise intensity increases?

Back 99

Both increases proportionately until the point at which O2 consumption can't increase anymore; then CO2 will increase more.

Front 100

Why does CO2 start to increase more as O2 consumption maxes?

Back 100

Because lactate starts to be produced, and CO2 is a byproduct of lactate production.

Front 101

How do you know if you've hit the anaerobic threshold?

Back 101

The RQ exceeds 1

Front 102

What is RER?

Back 102

Resp Exchange Ratio - the ratio of CO2 output to O2 uptake

Front 103

How is the RER related to the RQ?

Back 103

They are equal in homeostasis
RER>RQ in hyperventilation
RER<RQ in hypoventilation

Front 104

If a patient is hyperventilating and the RER is >1, does that mean their RQ is >1?

Back 104

No; bc it's being measured at the alveolar level, not cellular.

Front 105

4 other names for the Anaerobic Threshold:

Back 105

-Lactate threshold
-Lactic Acid threshold
-Gas exchange threshold
-Ventilatory threshold

Front 106

What is the Anaerobic Threshold?

Back 106

The point of exercise intensity and duration where arterial lactate increases and causes a metabolic acidosis

Front 107

Where is the AT?

Back 107

At 50-60% of maximal exercise capacity

Front 108

How much will lactate levels increase if a person has hit their AT?

Back 108

By about 4 mEq

Front 109

What is the O2 Ventilatory Equivalent?

Back 109

The ratio of Total ventilation (minute vent.) to O2 consumption (uptake)

Front 110

What is the normal O2 ventilatory equivalent during moderate exercise?

Back 110

20:1

Front 111

What happens to the O2 Vent Equivalent as exercise intensity goes up?

Back 111

The VE goes up but only to 100:4 which is like 25:1

Front 112

So how much does total ventilation have to increase for every extra liter of O2 consumed by the cells during exercise?

Back 112

By 20 L (ratio of 20:1)

Front 113

If the VE is like 80:1 what does that tell you?

Back 113

The person is hyperventilating - their ventilation is greatly increased but not their O2 consumption.

Front 114

What would a VE of 10:1 tell you?

Back 114

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

Front 115

What is the resting VE for CO2?

Back 115

A little higher than that for O2

Front 116

Where does the VE for O2 deviate from 20:1 to be more like 25:1?

Back 116

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

Front 117

Look at the powerpoint you made for this

Back 117

ok

Front 118

What happens to the VE for O2 after exercise?

Back 118

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

Front 119

What happens to the body's MAP during exercise?

Back 119

It increases somewhat

Front 120

What happens to diastolic BP during exercise?

Back 120

It doesn't increase much

Front 121

What happens to systolic BP during exercise?

Back 121

It increases significantly!

Front 122

So why does MAP increase somewhat during exercise?

Back 122

Because of the widening of the pulse pressures

Front 123

What happens to TPR during exercise?

Back 123

It drops to increase perfusion

Front 124

What is the magic number for exercise physiology?

Back 124

50-60% max exercise capacity - that's the anaerobic threshold, when everything changes.