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Oxygen Debt
Oxygen debt
is the oxygen that needs to be replaced or paid back to the various
systems in the body, such as the lungs, hemoglobin and myoglobin (found
in the muscles of the body) and body fluids. This repayment of oxygen
would catabolize the lactic acid formed in the muscles back to carbon
dioxide and water.
When the
energy required by the body exceeds the oxygen supply available to the
body, the muscles get their oxygen from the breakdown of the ATP
(Adenosine Triphosphate) in the body. When this is also consumed, then
additional ATP is produced by glycolisis without the use of oxygen (as
it normally happens when ATP is produced in the body) and this process
is called anaerobic glycolisis. This in turn, converts the pyruvic acid
into lactic acid, which is then transported to the liver where it is
broken into its two basic components, glucose and glycogen. Hence, the
muscles get their energy supply when needed.
When a
person goes through this process, he/she normally becomes short of
breath, since all of the oxygen is consumed by the muscle cells as a
result of the strenuous exercise involved, and the rest of the body
feels the need to supply more oxygen faster. This is when the person
starts gasping for breath, which will be fast and shallow.
Oxygen
Requirement for Highly Strenuous Exercises
There is a
maximum possible level of oxygen consumption during exercise and this is
known as maximal oxygen uptake and athletes develop it to about twice
the capacity of a normal non-athletic person. This permits the athletes
to perform astounding feats with less effort than a non-athlete would be
able to. The maximum oxygen uptake is achieved through specially focused
training that gradually builds it up to the maximum possible levels. The
athlete can never afford to let this level fall, and hence would require
continuous training to maintain the required maximum level once it has
been achieved.
The
Oxygen Debt
As soon as
the demanding type of exercise has ceased, the body reverses the
processes in order to refill the oxygen that it has been depleted from
different parts of the body. The following four major tasks are involved
in the reversal process:
-
ATP is restocked.
-
Lactic acid is
catabolized and removed (this is felt as acute pain in the muscles
similar to a burning sensation).
-
Refilling the store
houses of oxygen in the myoglobin (a compound similar to hemoglobin
that is found in the muscles).
-
Glycogen is restored.
There are
two major parts of oxygen debt:
-
A fast component where
the oxygen is reversed quickly through synthesis, which restores
phosphagen in the muscles in the form of ATP, and PC – this
component is known as Alactacid oxygen debt. This process is
concurrent with the replenishment of oxygen levels in the muscle
myoglobin.
-
A slow component where
the oxygen replenishment is used to remove the lactic acid
accumulated in the blood and muscles – this component is known as
Lactacid oxygen debt.
The oxygen
debt would be in excess of the normal pre-exercise quantity of oxygen
available in the body. Normally, the excess oxygen would be replenished
in about 30 to 60 seconds after the exercise has ceased when the
exercises are mild. However, the time of replenishment can take more
than 24 hours when the exercises are extremely strenuous and there is
lactate build up in the blood.
The last
phase, i.e. the replenishment of glycogen in the liver depends upon how
strenuous the exercises were and how much the oxygen debt in the body
is. The period of replenishment varies a lot, from 2 hours to a number
of days. It is worthwhile to mention that the replenishment is usually
very fast in the initial hours after the exercises cease. Once a
comfortable level has been achieved, the replenishment slows down and
may span over a few days. This process can be helped and accelerated
with the help of a high-carbohydrate diet.
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