Lecture 13 - Exercise At Altitude

Question 1

What four things decrease as you increase altitude?

What increases?

Answer 1

PO2 (partial pressure)
Temperature
Boiling point of water
PH2O

Solar radiation

Question 2

What is the respiratory response to high altitude once baroceptors and chemoceptors detect change? Include Bohr effect

Answer 2

1) Pulmonary ventilation (breathing rate) increases due to tidal volume increase, reducing CO2 concentration in blood, causing pH increase and respiratory alkalosis. This inhibits chemoreceptors and lowers ventilatory drive
2) Oxyhaemoglobin dissociation curve shifts left by alkalosis due to increase in oxygen affinity. Normally, Bohr effect ensures at lower pH that oxygen is given up easier. 2,3-BPG binds better to deoxygenated haemoglobin so will decrease oxygen affinity, causing oxygen release near respiring tissues

Question 3

What is the response when the body is deprived of adequate oxygen supply? What is this called?

Answer 3

Low PO2 at altitude sensed by carotid body > alerts brain which signals to increase breathing rate
This increases heart rate and dilates the peripheral blood vessels

Called hypoxia

Question 4

What do carotid bodies do?

What 2 types of cells are they made of?

Answer 4

They monitor arterial blood oxygen levels and stimulate breathing in response to hypoxia

Glomus (type 1) which is responsible for O2 sensing e.g hypoxia triggers AP in glomus
Type 2 which resembles glial cells

Question 5

What is the cardiovascular response to altitude?

Answer 5

Decrease in plasma volume and haematocrit due to respiratory H2O loss and wee increase
Sympathetic nervous system releases NA/A to alter cardiac function
Cardiac output varies between submaximal vs maximal activity

Question 6

Compare cardiac output in submaximal vs maximal activity at altitude

Answer 6

Submaximal - decrease in stroke volume due to decreased plasma volume > increase in heart rate but decreases thereafter as high heart rate not efficient way to deliver oxygen to tissues

Maximal - decrease in stroke volume due to decreased plasma volume AND decrease in maximum heart rate due to less sympathetic nerve activation, leading to reduced VO2 max

Question 7

Hypobaric conditons * oxygen * to muscles, * capacity to perform * * or * * activities

Answer 7

Limit; delivery; reducing; high intensity; prolonged aerobic

Question 8

VO2 max * with altitude

Answer 8

Decreases

Question 9

What is the renal response to high altitude?

Answer 9

Decrease in plasma volume due to increase in urination
Increase in EPO release to stimulate RBC production
Excretion of HCO3 ions to offset respiratory alkalosis

Question 10

Describe respiratory alkalosis process in more detail (4)

Why does hypocapnia develop?

Answer 10

Alveolar hyperventilation
Decrease in partial pressure of PCO2 (arterial - called hypocapnia)
Increase ratio of bicarbonate concentration to PCO2
Increased pH

A strong respiratory stimulus causes the respiratory system to remove more CO2 than is produced metabolically

Question 11

What is the metabolic response to altitude?

Answer 11

Increase in BMR (carb reliance)
Hypoxia conditions leads to increase in anaerobic metabolism
Initial lactic acid increase but then lactate paradox: natives make less than expected as they’ve acclimatised despite no VO2 max change

Question 12

What are the nutritional needs at altitude?

Answer 12

Increases BMR
Reduced appetite
Advice - eat lots, drink 3-5L and eat more iron due to more RBC’s

Question 13

• performance is * at * altitude whereas * exercise more affected by * conditions

VO2 max * as a * of sea level VO2 max

Answer 13

Anaerobic; unaffected; moderate; aerobic; hypoxic

Decreases; percent

Question 14

Define acclimatisation (6)

Answer 14

Changes within lifetime; within individual; results from environmental change; reversible change; due to natural conditions; phenotypic change and ecological response

Question 15

Define acclimation (7)

Answer 15

Changes within lifetime; within individual; results from environmental change; reversible change; due to experimental conditions; phenotypic change and ecological response; improves performance

Question 16

Define adaptation (6)

Answer 16

Occurs in groups; changes over many generations; due to environmental change; irreversible; due to natural or experimental conditions (e.g artificial selection); genetic change and evolutionary response

Question 17

Describe the four acclimations to altitude

Answer 17

1) pulmonary - increase in ventilation rate and depth, diffusing capacity
2) blood - increase in EPO, tissue vascularity, 2-3 BPG, plasma volume returns to normal, potentially polycythaemia
3) muscle - decrease in oxidative capacity, glycolytic enzyme activity and mitochondrial function, fibre area and mass, increase in capillary density
4) cardiovascular - nothing major, VO2 max never improves much

Question 18

When competing at altitude, what can you do?

What is the best advice?

Answer 18

Compete immediately as you won’t have adverse effects yet or after 2 weeks, so you have worse effects over but some acclimation

Live at altitude, train at lower levels and compete at sea level

Question 19

What are the health risks of altitude?

Answer 19

Altitude sickness 
High altitude pulmonary oedema 
Hypothermia
Frostbite
Cardiorespiratory effects
Exercise induced asthma