The air is
thinner at high altitudes so there are fewer oxygen molecules per volume of
air. With each breath taken less oxygen is delivered to the working muscles and
to compensate for the decrease in oxygen the body makes adjustments, some of
which are immediate responses whereas others form and improve over the time
spent in such conditions. The changes made by the body is called
acclimatisation and if we don’t acclimate properly there are high chances of
getting altitude sickness. Although some improvements can be noted there are
also some severe disadvantages that an be linked with being in high altitudes
for a long period of time.
The
immediate responses include increased breathing and increased heart rate, which
aim to supply the working muscles with the necessary amount of oxygen needed to
function properly. The kidneys produce a hormone called erythropoietin, which
will stimulate the increase in the production of red blood cells. By training
at high altitudes athletes aim to allow their bodies to produce more red blood
cells than they would require at sea level; the number of red blood cells
increase from 40-50% of blood volume to 50-70%. It is believed that the higher
concentration of red blood cells will last for 10 to 14 days which will give
them a competitive advantage. More red blood cells cause the body to use the
maximum amount of oxygen possible resulting in greater energy being produced by
respiring cells. This improves you VO2 maximum (how much oxygen your body can
use and convert to energy from food), so the body can obtain maximum energy
during competitions. However, it has been noted that the VO2 maximum level is
much lower at high altitude than at sea level.
After being
at high altitudes there are also some changes that occur in the body to give a
competitive advantage to the athlete. There is also an increase in the number
of small blood vessels, an increase in buffering capacity and changes in the
microscopic and function of the muscles. As well as increase red blood cells
there is more haemoglobin in the blood so more oxygen can be carried by the red
blood cells. The stroke volume of the heart increases so more blood is pumped
for every heart beat as the heart increases in size resulting in broader
chests, which increase the lung capacity. The maximum heart rate and cardiac
output will decrease so athletes will have greater endurance.
Although it
can be seen that there are obvious benefits of training at high altitudes but
it could also cause problems which could cancel out the benefits. Too many red
blood cells could make the blood thicker which results in the speed of blood
flow decreasing. The heart will not be able to pump blood around the body at
the same rate it used to function at, this will reduce the amount of oxygen
reaching respiring cells; which goes against the whole idea of getting a
competitive advantage. There are chances of the body’s immune system weakening,
and changed to muscles chemical make-up. This makes it easier for pathogens to
enter the body so greater chances of illnesses.
A new
training method is being used by athletes to avoid the above issues called
‘live high- train low’. The concept behind this is that training will be done
sea-level and they will live in high altitudes, this gives them the beneficial
effects of high altitudes but reduces the exposure time to hypoxia.
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