Exercise Physiology: Oxygen, Heat and Fluids

Question 1

What is maximal oxygen uptake?

Answer 1

the level where the amount of oxygen doesn’t increase for the increase in intensity

Question 2

What is VO2 max dependent on?

Answer 2

cardiac output

Question 3

What are the three cardiovascular responses to exercise?

Answer 3

increase oxygen supply to skeletal and cardiac muscle, facilitate carbon dioxide and heat removal, maintain MAP

Question 4

What circulation is decreased in exercise?

Answer 4

splanchnic and renal

Question 5

What circulation is increased in exercise?

Answer 5

muscle, coronary

Question 6

What happens to skin circulation in exercise?

Answer 6

it will increase with heavy exercise to facilitate heat loss but with maximal exercise it will decrease in order to maintain perfusion to the brain and muscle

Question 7

What is the mechanism of vasodilation in skeletal muscle in exercise?

Answer 7

NO, acid, ATP (from RBCs as they desaturate Hb)

Question 8

What causes post exercise fainting?

Answer 8

stop the muscle pump - stop venous return - sudden reduction in CO - faint

Question 9

What is functional sympatholysis?

Answer 9

the chemical dilators acting on sympathetic nerve endings to reduce the sympathetic vasoconstrictor effect

Question 10

Why do athletes have a lower HR at rest?

Answer 10

because they have a higher SV

Question 11

Why do athletes have a higher SV?

Answer 11

because they have a larger chamber size and expanded blood volume

Question 12

Why do athletes have a higher VO2 max?

Answer 12

because they have a higher CO due to an increased SV

Question 13

What is conducted vasodilation?

Answer 13

a mechanism that explains how vasodilation can occur in more proximal vasculature due to electrical signalling from the capillaries that receive the local vasodilator mediators

Question 14

What is the effect of exercise on systolic and diastolic blood pressure?

Answer 14

systolic blood pressure is a reflection of CO so will increase, diastolic blood pressure is a reflection of peripheral resistance and so will stay relatively stable or fall slightly

Question 15

What is the effect of exercise on MAP?

Answer 15

it will increase because as the HR increases the heart will spend less time in diastole so MAP will reflect systolic blood pressure

Question 16

What happens to the baroreflex in exercise?

Answer 16

the baroreceptors are reset so that a high MAP and high HR can be maintained

Question 17

What is cardiovascular drift?

Answer 17

increased HR and decreased SV with prolonged exercise

Question 18

What promotes cardiovascular drift?

Answer 18

hyperthermia, dehydration, increased adrenaline, peripheral displacement of blood volume to cutaneous circulation

Question 19

What is the theory behind why compression garments are used?

Answer 19

decreases peripheral displacement of blood volume to cutaneous circulation so reduce the cardiovascular drift effect

Question 20

Why does HR increase before you begin exercising?

Answer 20

because there is central control and the motor cortex can influence the CV centre

Question 21

How is the baroreceptor reset in exercise?

Answer 21

feedback from the muscles communicates to the CNS to inform about the adequacy of the blood supply

Question 22

What happens to the autonomic nervous system in exercise?

Answer 22

initially parasympathetics (vagus) withdraws and then get an increase in sympathetic activation

Question 23

What are the microvascular adaptations to training?

Answer 23

increased capillary density and increased capillary recruitment so that the increased CO is better able to be distributed to the muscle

Question 24

What controls ventilation during exercise?

Answer 24

initially ventilation is proportional to oxygen needs, but with further exercise other stimuli such as acidosis will further increase ventilation rates so that more CO2 can be blown off

Question 25

How is pulmonary gas exchange influenced by exercise?

Answer 25

Its not - although the transmit time is shorter since gas exchange is perfusion limited not diffusion limited the gas exchange can still be achieved unless there is disease e.g. COPD or asthma

Question 26

What controls ventilation?

Answer 26

chemoreceptors, stretch receptors in lungs, mechanoreceptors in muscle, pressure receptors, thermoreceptors, hormones, pain receptors, higher centres

Question 27

What is the of oxygen in the control of ventilation during exercise?

Answer 27

no role

Question 28

Why is it good for athletes to have a lower ventilation rate?

Answer 28

because it lowers the feeling of discomfort due to breathlessness and it lowers the oxygen cost of breathing

Question 29

What is the main determinant of VO2 max?

Answer 29

oxygen delivery not oxygen consumption

Question 30

How can the body lose heat?

Answer 30

conduction, convection, radiation, evaporation

Question 31

What is the major mechanism of heat loss?

Answer 31

sweat evaporation

Question 32

What is the major mechanism of heat loss for swimmers?

Answer 32

conduction

Question 33

What happens to CO with increase in temperature?

Answer 33

increases so that you can increase blood flow to the skin

Question 34

What is the role of pre cooling?

Answer 34

if lower your body temperature before exercise you will be able to last for longer in the heat because you will go to the same core body temperature

Question 35

What is the effect of exercise induced dehydration on plasma?

Answer 35

lose plasma volume but not as much compared to interstitial and intracellular volumes

Question 36

What are the benefits of fluid ingestion on exercise?

Answer 36

increased blood volume, decrease HR, higher SV and CO, lower core temperature, lower plasma sodium, reduced muscle glycogen use, enhanced exercise performance

Question 37

What happens after exercise?

Answer 37

RAAS activation because you are dehydrated