Phys 65: Exercise

Front 1

What are the three systems of energy used to power muscles? How long do they last? Power?

Back 1

1. Phosphagen (ATP+pohphocreatine), 8-10 seconds, most powerful
2. Glycogen- latic acid 1.3-1.6 minutes, moderately powerful
3. Aerobic system (glucose, FA, AA) limited by nutrient supply, least powerful

note balance between power and duration

Front 2

How does tidal volume change with exercise at varous intensities

Back 2

At low intensity exercise, VT increases, at high intensity frequency increases

Front 3

T/F alveolar ventilation increases proportionately with minute ventilation as frequency increases with exercise

Back 3

False, although both increase, the increase in dead space is much less than the increase in tidal volume. If minute ventilation doubles, alveolar ventilation will more than doulbe but alveolar ventilation will not exceed minute
ventilation

Front 4

Describe the change in ventilation rate over the course of exercise

Back 4

1. abrupt increase at onset of exercise 2. steady increase to plateau during exercise 3. abrupt decrease at the end of exercise 4. gradual decline post exercise to repay debt

note psychogenic vs. physiologic cue to increase

Front 5

how does the ventilation perfusion ratio change with exercise

Back 5

Since pulmonary blood flow increases with exercise (because CO increases) more capilliaries are perfused. This result in a more even distribution of V/Q ratios and a decrease in physiologic dead space.

Front 6

Explain how the components of VE  increase during exercise

Back 6

At first, the tidal volume increases to 50-60% of VC at the expense of IC. After this point, increases in VE are due to increases in frequency

Front 7

describe the respiratory steal phenomenon

Back 7

with exercise, the cost of ventilation increases from 2-5% of VO2 at rest to >30% during exercise, despite this fact, heart rate and not respiration is the limiting factor in of exercise capacity  in heathy adults

Front 8

describe the relationship between ventilation and O2 consupmtion

Back 8

fairly linear, ratio of total ventilation to O2 consumption is about 24:1, both can increase in the well trained athelete

Front 9

Explain how the components of cardiac output change during exercise. How is this different for trained althelets

Back 9

Stroke volume increases about 50%, heart rate increases >250%, in untrained athletes CO can increase 4 fold, in trained it can increase 6-8 fold. Stroke volume reaches its maxium at 50% max CO, further increases in CO are due to  increases in heart rate

Front 10

Describe the relationship betwewen oxygen consumption and cardiac output as work output increases

Back 10

fairly linear, oxygen consumption increases in proportion to the increase in cardiac output as work output increases

Front 11

how can cardiac output be calculated based on oxygen consumption

Back 11

CO=oyxgen consumption/ C (a-v) O2 (remember content is bound + dissolved)

another way to look at it: O2 consumption=CO x change in O2 content from aterial to venous

Front 12

Describe the similarities and differences in an athlete's heart vs. failing heart

Back 12

both have increases heart mass but in the athlete this is due to exercises induced remodeling which is an increase in muslce mass leading to enhanced cardiac function. In the failing heart, the increase in mass is due to the accumulation of collagen but  loss of myocytes leading to heart failure. Exercise induced remodeling is reversible, pathologic induced remodeling is not

Front 13

Describe the jpattern of blood flow to an exercising muscle (rythmic exercise)

Back 13

Blood flow to the muscle increases during exercise but decreases intermitently as the muscle contracts. Continuous contractions lead to fatigue due to decrease in O2 delivery and nutrients.

Front 14

What is the diffference between the respiratory quotient and RER

Back 14

RQ=rate of CO2 produciton to O2 consumption, used to estimate fat and CHO utilization (RQ=1=CHO, RQ=0.7=FA, 0.8=protein);

RER is the ratio of CO2 output to O2 uptake by the lungs, this is what we actually measure, in homeostasis it will equal RQ but after anabolic threshold it will be >1 (more CO2 must be put out to buffer lactic acid)

Front 15

Describe the two portions of oxygen debt makeup at the end of exercise

Back 15

1. early portion O2 debt is the alactacid debt, reconstitutes the phosphagen system and repays stored oxygen 2. the latter portion is lactic acid removal

Front 16

How does the ventilatory equilavent ratio for oxygen and CO2 change as exercise increases?

Back 16

At rest, the VE/VCO2 is greater than VE/VO2 (29:1 vs 24:1). At the anaerobic threshold they are equal. Beyond the threshold VE/VO2> VE/CO2 because ???

Front 17

How does the VD/VT ratio change during exercise

Back 17

Although both the dead space and tidal volume increase, the tidal volume increases much more than the dead space so the ratio decreases

Front 18

CO=mean arterial pressure/ total peripheral resistance. How do these to factors change to lead to the increase in cardiac output seen with exercise

Back 18

1. there is a large increase in systolic blood pressure and a small increase in diastolic pressure leading to a slight increase in MAP
2. TPR drops dramatically (because the arterioles dilate, clockwise rotation of venous return curve means for a given RAP, more blood can return to the heart)

Front 19

Describe in general the neuroendocrine response to exercise

Back 19

increases in-GH, TSH, cortisol, catecholamines, glucagon, endorphins, glycogenolysis; Decrease-insulin; Basic point-keep blood sugar high enough to fuel activity

Front 20

What is the ventilatory compensation point

Back 20

After the anaerobic threshold, pH starts to decrease due to the production of lactic acid due to insufficient oxygen, the VCP is where over-ventilation begins so as to blow off enough extra CO2 to buffer the lactic acid, usually occurs within minutes of reaching threshold when the bicarb buffer system is exhausted

Front 21

when does the anaerobic threshold usually occur

Back 21

sedentary-4-6 times resting O2 consumption, trained-10-12 times

Front 22

what are some clinical indications for a CPET

Back 22

1. exertional shortness of breath despite normal static pulm fxn studies 2. determination of functional capacity 3. Dx exercise induced asthma

Front 23

what is O2 pulse

Back 23

O2 pulse=VO2 /HR

Front 24

how is a ventilitaory limitation determined (2)

Back 24

1. frequency above 55-60 breaths per minute,
2. breathing reseve <20% (BR=predicted Ve max-acutal Ve reached)

Front 25

How is a CV limitation determined (3)

Back 25

1.abnormal ECG, arrhtynmia, 2/3 degree heart block
2. Bp S >250 d>120,
3. O2 pusle <10ml/beat

Front 26

how is a gas exchange limitation determined (3 things)

Back 26

SaO2 >4% decrease from baseline, PaO2>10mg Hg form baseline, A-a gradient > 35mg Hg (normal is 6)

Front 27

how do you determine if an exercise test went ot max (4 items)

Back 27

1. HR 100% or more of predicted
2. RQ 100% or more of predicted
3. decrease in bicarb>4 meq/L
4. increase in lactate >4mMol/L

Front 28

What results from an exercise test would reveal a gas exchange problem (3)

Back 28

1. decrease in O2 sat by more than 4%
2. decrease in PaO2 by more than 10mmHg under BASELINE
3. A-a gradient >35 (normal is 6)

Front 29

what results would reveal a CV limitation to exerise (3)

Back 29

1. O2 pulse less than 10mL/ beat
2. abnormal ECG, heart block, arrythmia etc.
3. BP > 250/170

Front 30

where is the largest portion of oxygen stored

Back 30

Hb-1 liter

(others=0.5 L in lung, 0.25L dissolved in fluids, 0.3L as myoglobin)

Front 31

about how much of the oxygen debt is alactacid?

Back 31

3.5L

Front 32

What happens to end tidal oxygen during an exercise session that reaches an RQ>1

Back 32

end tidal O2 will actually increase because the subject is hyperventilating in order to blow off the excess CO2 that is accumulating (if RQ>1, then CO2 production>O2 consumption)

Front 33

What is the acceptable max respiratory rate?
Breathing reserve?
Problems here would indicate a ventilatory limitation

Back 33

55-60 bpm
reserve-less than 20% is abnormal

Front 34

What is the aceptable max BP and min O2 pulse? Problems here woudl indicate a CV limitation

Back 34

A BP greater than 250/170 or an O2 pulse less than 10mL/beat would indicate a CV limitation