cardiorespiratory adjustments in exercise

Question 1

3 muscle types

Answer 1

slow twitch - type I

fast twitch - type IIa and IIb

Question 2

slow twitch is carried out by what process

Answer 2

oxidative phosphorylation

Question 3

fast twitch is carried out by what process

Answer 3

relies on creatine phosphate to regenerate ATP

Question 4

physical characteristics of slow twitch muscles

Answer 4

– good blood supply
– lots of mitochondria & myoglobin
– mainly postural but also used in endurance events

Question 5

physical characteristics of fast twitch muscles

Answer 5

– not so dependent on blood supply or mitochondria
– large amount of glycolytic enzymes
– used in sprinting and “explosive” events

Question 6

ATP pool required for contraction is regenerated from three sources

Answer 6

– cellular respiration (requires O2)
– creatine phosphate (4 – 5x that of ATP)
– muscle glycogen

Question 7

when is creatine phosphate used

Answer 7

for short bursts of energy can be used to replenish ATP from ADP

Question 8

when is glycogen used?

Answer 8

– large stores of glycogen can be broken down to provide substrate for glycolysis
– yields 2 ATP and 2 lactic acid molecules, enough to function if O2
is insufficient
– however, it is limited and eventually muscle must depend on cellular respiration

Question 9

exercise intensity is defined in terms of

Answer 9

oxygen uptake

Question 10

how does oxygen consumption change with work during dynamic exercise

Answer 10

in a linear manner

Question 11

maximal oxygen consumption

Answer 11

VO2 Max

Question 12

how is maximal oxygen consumption measured

Answer 12

incremental increases in exercise intensity

Question 13

cardiorespiratory adjustment

Answer 13

• To facilitate O2 consumption and prevent fatigue there needs to be
the continued delivery of O2
to the muscle

Question 14

what can a lack of oxygen during respiration lead to

Answer 14

lack of O2 means anaerobic respiration and lactate acidosis

Question 15

• O2 delivery depends on three aspects

Answer 15

1. Getting O2
   into the body and blood (respiration)
2. Getting O2 from the lungs to the tissues (cardiovascular delivery)
3. Getting O2 from the blood to the respiring tissues (O2 extraction)

Question 16

how does the oxygen consumption and carbon dioxide production change during exercise

Answer 16

In exercise both O2 consumption and CO2 production increase

Question 17

how is oxygen delivery and CO2 removal facilitated during exercise

Answer 17

both respiratory rate and tidal
volume increase
– tachypnoea not hyperventilation

Question 18

how is respiratory function controlled

Answer 18

“chemically” controlled

– via peripheral and central chemorecptors

Question 19

how does peripheral receptor respond to adjustments and what does it respond to?

Answer 19

drive peripheral receptor due to increase in acidity

lead to hyperventilation

Question 20

anaerobic threshold

Answer 20

The anaerobic threshold is when demand for O2 exceeds delivery
– tissues start to respire anaerobically

Question 21

how can glycolysis continue

Answer 21

NADH must be recycled back to NAD+
– done by lactate dehydrogenase converting pyruvate to lactate
drops pH
increasing acidity
metabolic lactic acid acidosis
stimulates peripheral chemoreceptors and increased ventilation

Question 22

what drives cardiovascular adaptation

Answer 22

SNS

Question 23

How does SNS help adapt cardiovascular

Answer 23

Increase in cardiac output and the redistribution of blood flow
– SNS increase in heart rate and stroke volume as well as vasoconstriction
• Direct sympathetic action on heart rate and contractility
• Increased venous return and therefore stroke volume
– due to increased muscle pump, respiratory pump and venoconstriction
• Sympathetic vasoconstriction and metabolite vasodilatation alter
pattern of distribution
– away from GI, renal and to working muscle and heart

Question 24

hyperaemia

Answer 24

dilate all capillary vessel when there is greater surface area for perfusion and decrease in perfusion distance to accommodate greater oxygen demand
greater concentration gradient
no change in solute diffusity

Question 25

how does increased CO2 and H+ and temp affect oxygen delivery to tissue

Answer 25

reduce affinity for Hb - Bohr effect - shift dissociation curve to the right
promote oxygen delivery to tissue

Question 26

how is oxygen debt repaid

Answer 26

– fast: re-phosphorylation of ATP/creatine
– slow: lactate conversion back to glucose/glycogen
– ultraslow: increased metabolic rate after exercise

Question 27

oxygen debt

Answer 27

as the VO2

in excess of resting after exercise

Question 28

3 stages in which oxygen debt is incurred

Answer 28

– depletion of ATP, depletion of creatine phosphate then the build up of lactic acid

Question 29

why is there such thing as an oxygen debt

Answer 29

Adaptations aim to supply O2 to match demand during exercise - but when exercising is over the initial deficit will need to be repaid

Question 30

how does training affect muscle

Answer 30

increase muscle strength and resistance to fatigue
muscle hypertrophy - larger muscle fibres not hyperplasia - getting more muscle fibres
increased glycolytic and oxidative capacity - increased glycogen, ATP , phospho-creatinine, mitochondrial enzymes

Question 31

cardiorespiratory effects of training

Answer 31

Bradycardia and cardiac remodeling
reduced blood pressure - enhances endothelial function, inc. muscle capillary density
increased myoglobin and 2,3,BPG
reduced ventilation at same work rate - shift in anaerobic threshold

Question 32

other effects of training

Answer 32

increase VO2 max and O2 debt and anaerobic threshold

Question 33

during what time period can significant improvement be seen

Answer 33

8-10 weeks
30 min sessions, 2/3 times per week
60% max O2 consumption

Question 34

what will training not improve

Answer 34

– VO2 or the cardiac output at rest
– diffusing capacity or the haemoglobin concentration
– maximum heart rate