Altitude and exercise

Question 1

What are the environmental conditions at altitude? (7) What are the effects on the body?

Answer 1

1. low barometric pressure (decreases with increased altitude)
2. constituents of the air remain constant (O2, CO2, N2 %)
3. low PO2 (partial pressure of O2) = affects the PO2 and gradients in blood and tissues
4. increased wind speed
5. decreased air temperature by 1 deg. for every 150m
6. low water vapour pressure = low humidity = significant gradient between the body and the air = rapid evaporation from skin/clothing, rapid fluid loss from mouth and nose = dehydration
7. increased solar radiation: less distance to travel in the atmosphere, less moisture in air to absorb rays, snow/ice reflects radiation

Question 2

How does altitude affect partial pressure of 02 in the body?

Answer 2

Partial pressure of O2 is affected between:

1. air and alveoli
2. alveoli and blood
3. blood and tissues

diffusion gradient decreases significantly

Question 3

What are the acute cardiovascular responses to altitude? (5)

Answer 3

1. increase in submaximal heart rate
2. stroke volume remains the same or decreases slightly
3. maximum cardiac output remains the same or decreases slightly
4. decreased EDV caused by decreased plasma volume
5. increased BP and Q to compensate for low PO2 and loss of PV

Question 4

How does altitude affect exercise performance? (endurance, short and high intensity, jumping and throwing)

Answer 4

• overall limits exercise performance
• endurance: VO2 max decreased by 1% per 100m beyond 1500m, limited O2 delivery, greater HLa- accumulation = decreased performance
• short and high intensity = unlikely to limit performance, may be enhanced due to less dense air posing less resistance
• jumping and throwing: air resistance decreased = improved performance

Question 5

How does adaptation to altitude affect sea level performance?

Answer 5

• effects slowly reverse
  1. Hb mass, VO2 and time trail perfomance improve
  2. performance improvements are less consistent - 1-2%
  3. performance may be enhanced immediately on return and then 3 weeks after

Question 6

What are practical considerations when designing an acclimatization or acclimation program to improve sea level performance? When is it best used for?

Answer 6

natural acclimatisation = 1800-2500m 2-4 weeks
artificial acclimation = 3000m 2-4 weeks ~14h/day
- increase training progressively
- must have good nutrition
- screen for serum ferritin; consider iron supplements
- may not be worth going if ill or injured
- response wont always be replicated on exposure

Best used for:

1. enhancing if forced to compete at altitiude
2. enhancing fitness early in the season
3. accelerating a rebuild phase
4. post-injury to return to pre-injury fitness quickly or as a way of enhancing training load without adding physical load
5. can be used to enhance specific competition performance if times correctly

Question 7

What are the acute pulmonary acid-base responses to altitude? (2)

Answer 7

1. hyperventilation due to decreased PO2 stimulating the hypoxic drive (increase ventilation, increase alveolar PO2, increase arterial PO2, saturation and O2 content
2. alkalosis caused by increased pH due to reduction in carbon dioxide with hyperventilation

Question 8

List the acute metabolic responses to altitude? (4)

Answer 8

1. increased RMR due to increased HR and ventilation
2. decreased appetite
3. increase catecholamines = increase CHO usage
4. VO2 max decreased

Question 9

How does altitude affect sleep and sensory function?

Answer 9

1. disrupted sleep - battle of hyperventilation and reduced ventilation
2. decreased sensory function: light sensitivity and visual acuity

Question 10

List the chronic cellular adaptations to altitude acclimatization? (4)

Answer 10

1. possible increased capillarization of skeletal muscle
2. increased myoglobin
3. increased mitochondrial density
4. increased aerobic enzymes in muscle

Question 11

List the chronic hematologic adaptations to altitude acclimatization? (4)

Answer 11

1. decreased plasma volume
2. increased hematocrit
3. polycythaemia -increased haemoglobin concentration (enhanced O2 carrying capacity)
4. increased total number of red blood cells

Question 12

List the chronic pulmonary acid-base adaptations to altitude acclimatization? (2)

Answer 12

1. hyperventilation

2. excretion of base (HC03-) via the kidneys and concomitant reduction in alkaline reserve

Question 13

List the chronic cardiovascular adaptations to altitude acclimatization? (4)

Answer 13

1. submaximal heart rate remamins elevated
2. submaximal cardiac output falls to or below sea-level values
3. stroke volume decreases
4. maximum cardiac output decreases

Question 14

Describe the methods of altitude training? (3)

method, aim, protocol

Answer 14

1. Live high: train high - classic method: 2-4 weeks, 1500-3000m, develop Hb mass and enhance training stimulus, balance between getting altitude exposure but not blunting training performance
2. live high: train low - get altitude hypoxic stimulus and avoid loss of training intensity, live on mountain and come down for training or use altitude tents when resting (normobaric hypoxia), >2500m, ~14h/day
3. live low: train high - masks and chambers, possibly some anaerobic benefit, strength and hypertrophy may be enhanced, no chronic adaptations

Question 15

What factors affect Hb mass?

Answer 15

• Altitude dose
• Genetic
• Iron levels -> pre trip check and supplementation
• Nutrition
• Immune and injury status (mostly inflammation)

Question 16

What are the normative Hb levels at sea level and after altitude training? for males and females

Answer 16

Sea level - males: 12-16 females: 11-14

After altitude - males: 16-18 females: 14-16