Exercise Physiology

Question 1

What is oxygen extraction?

Answer 1

• pulling oxygen from circulation to support cellular production of energy for muscle contraction
• normal 5vol% a-vO2 difference
• more O2 extracted by working muscles

Question 2

What is oxygen diffusion?

Answer 2

• A-C membrane, gas exchange

- increased cardiac output, increased perfusion, increased pulmonary vascular pressure thus more uniform distribution

Question 3

What is oxygen consumption?

Answer 3

• resting VO2 = 3.5 ml/kg/min
• exercising VO2 increases directly with level of muscular work
• maximum VO2 depends on genetics, conditioning, presence/absence of disease

Question 4

At rest, what does 1 MET equal?

Answer 4

3.5 ml/kg/min

Question 5

What is normal VO2 max?

Answer 5

> 84% of predicted

Question 6

How can O2 consumption be predicted?

Answer 6

from work rate

Question 7

What is VO2 peak?

Answer 7

where exercise is stopped below maximal capacity for O2 transport due to dyspnea, pain, peripheral vascular disease

Question 8

What is carbon dioxide production?

Answer 8

• VCO2, normal 200 ml/min or 2.8 ml/min/kg

- exhaled CO2 depends on matching alveolar ventilation

Question 9

What is the respiratory exchange ratio (RER)?

Answer 9

• VCO2/VO2 at mouth
• one way of determining lactate threshold
• normal 0.8 (greater than 1.0 reflects increased CO2 lactate buffering)
• affected by hypo/hyperventilation

Question 10

What is the respiratory quotient (RQ)?

Answer 10

• usually not measured directly
• ratio of VCO2 to VO2 at tissues
• CHO RQ 1.0, Fat RQ 0.7, combined at rest 0.8

Question 11

What is minute ventilation?

Answer 11

• depends on PaCO2 and dead space
• evaluates respiratory response
• healthy individuals < 70% of ventilatory capacity

Question 12

How do you measure breathing reserve?

Answer 12

MVV - VEmax

Question 13

In healthy individuals, how is end expiratory lung volume affected during exertion?

Answer 13

decreases

Question 14

In COPD patients, how is end expiratory lung volume affected during exertion?

Answer 14

increases causing a decrease in IC

Question 15

What is the dead space to tidal volume ratio?

Answer 15

• normally <0.25 with maximal exertion

- (PaCO2 - PeCO2)/PaCO2

Question 16

What is the normal P(A-a)O2?

Answer 16

10 mmHg

Question 17

What is the P(A-a)O2 with maximal exercise?

Answer 17

20-30 mmHg

Question 18

When does P(A-a)O2 increase?

Answer 18

heavy exertion and age

Question 19

What is PETCO2 and (Pa-ET)CO2?

Answer 19

• end tidal CO2
• estimates PaCO2
• resting normal difference is 2-3 mmHg
• maximal exertion 4 mmHg
• diseased lung values >10 mmHg

Question 20

What is PETO2?

Answer 20

• end tidal PO2
• plotted as a function of workload
• increase with hyperventilation associated with lactic acidosis
• can utilize to determine LT

Question 21

What is lactate threshold?

Answer 21

• commonly called the anaerobic threshold
• VCO2 and VE do not rise in proportion to VO2
• where pH stable until oxygen delivery does not meet demand

Question 22

How would you detect LT?

Answer 22

• normal value is 50-60% of VO2 max

- clinically breathlessness, muscle burning, muscle fatigue

Question 23

What is maximum heart rate?

Answer 23

• predicted HR max is 220-age
• HR increased linearly with increased workload
• maximum HR achieved just prior to exhaustion

Question 24

What is heart rate reserve?

Answer 24

• (HR predicted - HR actual)
• should be less than 15
• HR % of predicted >90%
• values outside this range indicate non-cardiovascular limitations