PSC1002/L19 Respiratory Changes during Exercise

Question 1

Define VO2max.

Answer 1

Maximal amount of oxygen delivered to the working tissues and utilised in aerobic metabolism

Question 2

What is the trained and untrained speed of VO2 response?

Answer 2

Trained 20s
Untrained 30-45s

Question 3

Describe the utilisation theory of VO2max.

Answer 3

VO2max is determined by the body’s ability to utilise the available oxygen

Question 4

Describe the presentation theory of VO2max.

Answer 4

VO2max is the ability of the body’s cardiovascular system to deliver oxygen to active tissues

Question 5

What did Saltin and Rowell (1980) conclude about the limiting factor of VO2max?

Answer 5

Delivery of oxygen to active tissues is major limiting factor to VO2max

Question 6

Give 2 examples of exercises used in a graded exercise test.

Answer 6

Large muscle group exercises
Running
Cycling
Rowing

Question 7

Describe how to conduct a graded exercise test.

Answer 7

Increase load stepwise every 1-4 minutes until subject cannot maintain desired work rate

Question 8

What did Myers et al (1991) show about exercise tests?

Answer 8

Ramp protocols represented high correlation between VO2 and workload

Question 9

What is a normal VO2max value for 18-25 year-olds?

Answer 9

30-40ml/kg/min

Question 10

Describe what occurs in the first stage of exercise. (2)

Answer 10

Immediate increase in ventilation (feed forward reflex)
Proprioceptors in muscles and joints -> motor cortex -> respiratory centre -> increased ventilation before any changes in PAO2 or PACO2

Question 11

Describe what occurs in the second stage of exercise. (2)

Answer 11

Mediated by peripheral and central chemoreceptors
Rise in plasma K+

Question 12

Describe what occurs in the third stage of exercise.

Answer 12

Ventilation rate remains elevated until ATP and CP stores return to normal

Question 13

What is ventilatory threshold? (2)

Answer 13

The point at which ventilation starts to increase at a faster rate than VO2
Reflects levels of anaerobiosis and lactate accumulation

Question 14

What is the Fick equation?

Answer 14

VO2max = Q x (a-v) O2c

Question 15

What mechanisms are responsible for increase stroke volume? (3)

Answer 15

Sympathetic venoconstriction
Skeletal muscle pump
Respiratory pump

Question 16

Increased stroke volume results from changes in what? (3)

Answer 16

Cardiac dimensions
Blood volume
Venous return

Question 17

By which mechanisms is stroke volume increased? (4)

Answer 17

Enhanced diastolic filling
Greater systolic emptying
Blood volume expansion & reduced resistance to blood flow
Decreased sympathetic drive slows HR

Question 18

Define cardiac output (Q).

Answer 18

Amount of blood pumped by the heart in 1 minute

Question 19

What factors affect a-vO2diff? (3)

Answer 19

Increased capillarisation
Increased capillary to fibre ratio
Increased capability (mitochondria & respiratory enzymes)

Question 20

Describe central adaptations to O2 transport. (3)

Answer 20

Achieved through low intensity training (70% VO2max)
Much slower 0 weeks to months
Need prolonged stimulus

Question 21

Describe peripheral adaptations to O2 transport. (3)

Answer 21

Achieved at high intensities (>90% VO2max)
Intervals between 2-8 minutes
Adaptations can be quicker (within 2 weeks)

Question 22

Describe the effects of detraining. (3)

Answer 22

Fairly quick initially then slow
Initial decrease in VO2max due to decreased SV
Decreased VO2max due to decreased a-vO2diff