Altitude

Question 1

Why do people train at altitude?

Answer 1

• Many sporting competitions are staged at altitudes.

- Reduced air density with increased exercise modifies aerodynamic drag and facilitates high-speed movements.

Question 2

How does ventilation adapt at altitude?

Answer 2

• PO2 is sensed by peripheral chemoreceptors.

- CO2 levels in the blood are reduced -> follows the pressure gradient.

Question 3

What is respiratory alkalosis?

Answer 3

In an effort to offset less bicarbonate ion. = less buffering of carbonic acid = pH better maintained.

Question 4

How does pulmonary diffusion respond to altitude?

Answer 4

• Pulmonary diffusion is not impaired.
• PO2 in arteries and alveoli are similar.
• Low arterial PO2 is a result of low alveolar PO2 and not an oxygen diffusion limitation.

Question 5

How does oxygen transport differ at altitude compared to sea level?

Answer 5

• At sea level 96-97% of haemoglobin has O2 bound to it.

- At altitude only 80% of haemoglobin sites saturated.

Question 6

Whats the effect of altitude on VO2 max?

Answer 6

VO2 max decreases with altitude.

Question 7

What are the cardiovascular responses to exercise at altitude?

Answer 7

• Decrease in plasma volume within first few hours.
• Exposure to high altitude triggers release of erythroprotein (EPO) from kidneys.
• During sub max exercise: SV is decreased and HR disproportionally increases leading to a slight increase of Q.
• During max exercise max SV and max HR are reduced.

Question 8

What does EPO do?

Answer 8

• Stimulates RBC production.
• EPO has been seen to increase mood and perception of physical conditioning.
  ↘︎ Suggesting EPO may modulate central fatigue.

Question 9

What happens when EPO is reduced significantly?

Answer 9

• Neocytolysis.

- Negative effect on mood.

Question 10

What is the hypoxia-inducible factor 1?

Answer 10

• Transcription factor that regulates oxygen homeostasis.

- Induced in response to continuous or intermittent hypoxia.

Question 11

Chronic adaptations to altitude training.

Answer 11

• Decrease in plasma volume.
• Increase in number of red blood cells.
• Increase in haemoglobin content.
• Decrease in muscle fibre areas and total muscle area.
• Increase in capillary density.
• Increase in pulmonary ventilation.
• Decrease in VO2 max with initial exposure, doesn’t improve much.

Question 12

Does altitude training improve sea level performance?

Answer 12

• Strong theoretical argument can be made for improvements in performance.
• Altitude-induced increase in RBC mass and haemoglobin levels improves oxygen delivery on return to sea level.

Question 13

Describe live high train low (LHTL)

Answer 13

Athletes sleep at moderate altitudes to simulate an increase in red blood cells, but avoid the diminished training effects by training at sea level.

Question 14

Describe an individuals response to LHTL

Answer 14

• Large individual variation in the change of physiological and performance measures.
• Normobaric LHTL induces reproducible mean improvements in VO2max and Respiratory cardiovascular systems.

Question 15

What is intermittent hypoxia?

Answer 15

Intermittent hypoxia at rest delivered by repeatedly switching between breathing hypoxic and normoxic
air for relatively short durations (60–90 min).

Question 16

What are the altitude training recommendations for endurance athletes?

Answer 16

• Endurance athletes could use intermittent hypoxic training during the pre-competitive phase.
• Twice a week, 30-45 mins high intensity exercises.
• Simulated altitude of 2500-3000m.
• High intensity exercises should be around anaerobic threshold, organised in series of 10-20 minutes.

Question 17

Name and describe the 3 phases in the return to sea level post altitude training.

Answer 17

1) Positive phase (first 2-4 days).
• Immediately post-training due to haemodilution and ventilatory changes from altitude.
• Variable performance improvements, resulting in potentially beneficial but
also unreliable performance outcomes.

2) Second phase.
• Reacclimatisation and reduction in performance.
• Potentially due to loss of any acute altitude-related neuromuscular
adaptation.

3) Third phase (15-21 days).
• Plateau in altitude adjusted fitness.
• Performance is enhanced.
• Optimal delay for competition.

Question 18

Benefits of repeated sprint training in hypoxia

Answer 18

• produces faster mean sprint times.

- improved fatigue resistance.

Question 19

How does resistance training differ in hypoxia?

Answer 19

• Low partial pressure of O2 exaggerates metabolite (eg. Blood La & anabolic hormones)
accumulation.
• Results in accelerated recruitment of higher threshold motor units.
• Subsequent adaptation – hypertrophy of motor units → greater muscle strength.