Exercise at Altitude Flashcards
What is Altitude? When does it start to affect performance?
The height or elevation of an area above sea level.
Altitude starts to have an affect around 1500m above sea level
What is barometric pressure and how is it affected by altitude?
As altitude increases, barometric pressure decreases, this is the pressure exerted by the atmosphere at any given point.
- Composition of air stays the same but partial pressure of oxygen(pO2) decreases, has a severe impact on performance.
What are the units of measurement for partial pressure?
mmHg (millimetres of Mercury)
How is the diffusion gradient affected by increased altitude?
As altitude increases, the greater the negative impact on the diffusion gradient.
E.g:
-Sea level pO2(159mmHg) - Gradient of 119 to capillary blood
-3600m above sea level(105mmHg)- 45% reduction to gradient of 65 to blood
- 8800m above sea pO2 (43mmHg)- diffusion gradient of 3 to capillary blood
How does altitude affect the CV system of an athlete?
Decreased pO2 in alveolar, decreased diffusion gradient to capillary blood, decreased haemoglobin and o2 association in blood stream, decreased o2 transportation to muscle tissues
- blood volume decreases- plasma volume decreases by 25% to allow increase density of Red blood cells
- stroke volume increases, increases heart rate
- maximal cardiac output, stroke volume and heart rate decrease during maximum intensity exercise.
Decreased o2 supply for aerobic energy production
How is an athletes respiratory system affected by high altitude?
- Breathing frequency increases at rest and during exercise.
- Reduced aerobic capacity and VO2 max, impacting on intensity and duration of an athletes performance before fatigue
What is acclimatisation?
A process of gradual adaption to a change in environment (for example lower pO2 at altitude)
How does acclimatisation benefit the CV system of an athlete?
-Increases in red blood cell production, due to increase release of erythropoietin(EPO). Release of EPO increases within 3 hours of altitude exposure, peaking 24-48 hours later.
- SV and CO reduce as oxygen extraction becomes more efficient.
After 10 days of acclimatisation, CO is lower at any sub-maximal intensity, compared to sea level
What is EPO?
A naturally produced hormone responsible for the production of red blood cells.
How does acclimatisation benefit an athletes respiratory system?
Breathing rate and ventilation stabilise, although remain elevated at rest, compared to sea level.
An athlete will never fully compensate and regain sea level vo2 max, no matter how long they spend at altitude prior to an event.
What other benefits are there of acclimatisation?
Reduced incidences of altitude sickness, headaches, breathlessness, poor sleep and lack of appetite.
