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ABOVE AND BELOW SEA LEVEL.....
Transcript of ABOVE AND BELOW SEA LEVEL.....
What happens to the environment when altitude increases?
The barometric/atmospheric pressure (force of the air) continues to decrease as altitude above sea level increases
In a given body of air, there are LESS particles
This means there is a decrease to the partial pressure of oxygen
Less oxygen can be taken in by the body with each breath
Have you noticed when you are in higher altitude, your breathing feels "heavier"??
How does this affect the body?
When the body is exposed to high altitudes, it needs to respond to handle this decreased pressure and lower amount of oxygen available
1. A more rapid breathing rate
You need to breathe more, even at rest, so your body can take in as much oxygen as it does at sea level - hyperventilation
2. Less oxygen passed to blood
The amount of oxygen that joins with haemoglobin, decreases (haemoglobin saturation)
3. Less oxygen is passed from the blood to the tissues that need it
4. VO2 Max decreases
The maximum amount of oxygen that can be taken up, decreases
For every 1000m above sea level, VO2max drops about 8-10%
1. Blood volume decreases
The body reduces the amount of plasma (watery part) to increase the RBC density
2. Short term increase to Cardiac Output
Stroke volume decreases (less plasma), heart rate increases and cardiac output increases
(after some exposure however, cardiac output decreases as the body adapts to less O2)
So, in the short term, altitude will decrease exercise performance
for endurance/ aerobic activities
Interesting though, less air and resistance at altitude actually gives anaerobic performance a bit of a boost for some people...
So if altitude makes it really hard on your aerobic performance, and oxygen use difficult - what is all this about "altitude training????"
Exposure to the altitude environment can actually lead to adaptations, that may provide benefits for aerobic training at sea level or to prepare for an altitude event - "acclimatisation"
At about 2000m above sea level (the height of mexico city), it takes about two weeks to acclimatise and experience adaptations
Every 600m requires an additional week
So what adaptations occur to help endurance activities?
1. Increase to
red blood cells & more Haemoglobin
The body releases erythropoiten, the hormone responsible for making red blood cells.
This raises haematocrit levels (the percentage of red blood cells in the blood)
2. Changes to cardiac output
More blood available takes the stress off the heart and the cardiac output goes back to sea level rates
3. Increased capillarisation
More capillaries around the muscles and blood vessels to allow for better oxygen transport
4. Increased production of mitochondria
Mitochondria are the structures in a cell where aerobic metabolism takes place - so more mitochondria means more efficient aerobic metabolism & oxygen use
Altitude Training Strategies
There are 3 different approaches to altitude training
Live High, Train High
Live High, Train Low
Live Low, Train High
Live High Train High
Full time exposure to the reduced oxygen environment
Means that athlete needs to train at a lower intensity
Live High, Train Low
Live for a period of time at high altitude, but still complete training closer to sea level
Live Low, Train High
Training camps at altitude ie: Arizona (which is at altitude)
Hypobaric chamber - preselects the barometric pressure to altitude for sleep
Hypoxic tents - reduced oxygen in the tent
Carlton FC has a training "room" for altitude
1. Fluid Loss
Body water evaporates more readily which leads to dehydration and other symptoms such as dry lips, mouth and throat
This is increased by exercise due to sweat loss and increased respiratory rate
Live at sea level, but complete aerobic training at an altitude
These simulate "altitude" at sea level
Altitude training has different results for different individuals
Recommendation is to ensure that athlete trains at an elevation that allows them to keep intensity
Mountaineers ensure that they acclimatise to altitude to allow some of the adaptations to occur
Below sea level.......
Many people enjoy scuba diving for recreation or are required to scuba dive for work
what happens as you go down deeper in water..?
With increased depth, comes greater pressure against the body from weight on the body - caused by the water and the atmosphere above
When the pressure increases, the gas volume will also decrease - lung volume will decrease
All the air in your body's cavities compresses
So what about if you just dive deep underneath the water, maybe when you are snorkelling
Some individuals will "hyperventilate" before they breath-hold dive - but why is this bad?
Expelling extra carbon dioxide allows you to hold your breath for longer, but the combination of diving, hyperventilating and exercise means that oxygen levels can be seriously compromised in the diver and they will lose consciousness
Reduction to the volume of the lungs (become compressed) due to increased pressure
The amount of gases absorbed into body at greater depths will decrease
Change in Carbon Dioxide to Oxygen levels signals your body to come up for air
Pressure on lungs too great for the muscles to withstand
Scuba diving allows the issues with breath-hold diving to be overcome - but how?
SCUBA stands for self-contained underwater breathing apoaratus
It was developed in 1943 by the French Oceanographer Jacques Yves-Costeau
A scuba system includes ...
A compressed air tank
Mouthpiece or Full Mask
there are two types of SCUBA system designs - an open-circuit or closed-circuit system
The open-circuit system is more common
How the Open Circuit SCUBA works..
Diver breaths in compressed air from the tank
A regulator reduces the pressure right before inhaling so it is at a safe pressure to breathe
Diver exhales into the external environment - these are the bubbles you see
Closed-circuit systems do NOT have a regulator and exhaled air is recycled
A standard tank can supply about a 0.5-1hr dive
What do SCUBA divers wear?
Wet suit - rubber suits providing protection against cold stress
- traps water against the diver's skin providing a layer of water that is heated by the body
Dry suit - often worn over insulating garments to maximise protection in the cold - completely prevents water entry
Some dangers associated with SCUBA diving
When air is breathed at a depth, it doubles in volume as you get closer to the surface
Normally breathing needs to occur heading up to the surface
If a diver takes a big breath and doesn't continue to exhale in ascent, the gas eventually ruptures the lungs because it expands
Air bubbles can also escape from the respiratory system and enter the vessels - they can travel to the heart or brain and restrict blood supply
To fix an air embolism - the body needs to be rapidly recompressed in a chamber
Pneumothorax - Lung Collapse
Air that is forced through the little alveoli when lung tissue erupts (as a result of the embolism previously mentioned) - can sometimes head to the sac around the lungs
As it continues to expand as you get closer to the surface, this collapses the lung
Treatment is surgery to extract the air pocket
"The Bends" or "Decompression sickness"
& what about up....up...and further up....
What is the atmosphere like in Space?
What are some countermeasures for astronauts?
What adaptations occur to the body while in space?
You probably are already aware that in space, there is less gravity. We refer to this as "microgravity"
Microgravity creates an environment where
An astronaut doesn't feel force pulling it down like you do on earth
Liquids in a spacecraft will not remain in an open cup or glass
Astronauts need to hold on to something to keep them from floating freely
Microgravity's influence on the body
Blood and fluids shift upward causing puffiness
Fluid shift also creates red eyes, skinny legs, some headaches, congestion
Waist girth decreases
Because of the lack of force on the intervertebral discs - the body stretches increasing height
Joints move toward the midpoint of the body
Reduced body fluids decreases the heart's total work effort
Heart reduces in overall size
Muscles experience "atrophy" ( a decrease in size ) because they are not being used
Muscle mass and strength declines
Bones de-mineralise and calcium is lost
Without appropriate countermeasures against microgravity - the body can suffer from effects that mimic being on bed rest for 30 days
In flight exercise - treadmill walking & running, cycle ergometry, leg rowing, resistance exercises
Exercise does not usually occur for first 48-72 hours so astronauts can get over space motion sickness
Using a human centrifuge to simulate microgravity
The air in the mask before a dive is the same pressure as the surface
When the diver goes down deeper, there is a difference in pressure between inside and outside the mask which creates a vacuum
This is why your goggles can feel "tight" when you dive deeper
Face mask squeeze can rupture the blood vessels in the eye and eyes can even be sucked out!
Divers make sure they exhale through their nose into the mask to balance the pressure
Again an issue with the pressure differences, is trying to equalise pressure in the eustachian tube which is in your middle ear
This is similar to what occurs when you are on a plane
Scuba divers blow gently against closed nostrils to equalise pressure and "pop" the ears
Problems arise if there is an infection where the eustachian tube is blocked - can lead to tissue damage or a ruptured ear drum
Earplugs should NEVER be used as the pressure will force it down the ear canal
This is where nitrogen in the water dissolves into the blood
It has an incredibly effect on the body, numbing the central nervous system and is often described as being similar to someone being intoxicated
Treatment is to ascend to shallow depths for a usually rapid recovery
When a diver ascends rapidly, the external pressure on the body will decrease very dramatically
The excess nitrogen in the body leaves
The Bends, is where nitrogen bubbles form in the body's tissues, caused by ascending too rapidly following a deep dive
The Bends can be fatal. Treatment involves use of a hyperbaric chamber which forces nitrogen back into the solution (not as a gas)
SHORT TERM RESPONSE TO ALTITUDE
Some exercise scientists, coaches believe that altitude training can have benefits at sea level
What happened in 1968?
The Mexico City Olympic Games - over 2000m elevation
Endurance athletes noticed a significant decline to their performance