Did you know we humans have about 639 muscles in our body,
with each of them having their own name? Most of these muscles are
attached firmly to the bones of the skeleton, which make up the
framework of the body. They are highly important parts of the body
because without them we would not be able to move, eat,
breathe, talk and even the heart would stop because the
blood gets pumped in and out of the heart only through
muscular action! Exercise is a good way to keep these muscles in
shape, but if we exercise for too long a time, the muscles
start to ache very badly and this is due to anaerobic respiration.
Under normal conditions, the body cells go
through aerobic respiration, which is a long process where
oxygen is used to convert the stored up glucose molecules,
completely into energy. This type of respiration takes
place in most living creatures, but there are a few
parasitic worms and lower forms of plants (bacteria and yeast) that
breathe anaerobically, that is, in the absence of oxygen.
Anaerobic respiration also takes place in human beings when we
exercise rigorously. During this time, we tend to take in less
oxygen and this lack of oxygen prevents the oxygen from breaking
down completely. This 'oxygen debt' results in the
formation of an acid, or rather a 'poison' called lactic acid. This
lactic acid gets stored in the muscles and causes the pain. The
tiredness is caused by the production of different
types of toxins, which are carried by the blood throughout the body.
The only way to remove this acid is to rest for a while,
take in deep breaths of air (the extra oxygen helps to convert the
lactic acid into a safer form) and the pain slowly subsides. The
pain is actually a good way to control the body's activities.
If a person continues to exercise and ignores the warnings
being given by the body, the person might faint due to lack of
oxygen or seriously sprain some of the muscles.
There are many differences between the two types of respiration, the
most important being the difference between the amount of
energy released. In aerobic respiration, we get about 38
ATP molecules of energy from a single glucose molecule, while in
anaerobic respiration only 2 ATP molecules of energy are released
for the same quantity of glucose. So it is always advantageous to
take breaks while exercising; while resting, body removes
any waste products, the cells get rejuvenated, the brain's nerve
cells get re-charged, the joints of the body replenish their
supplies of lubricants and much more. The body is then fit
enough to carry on with the exercise and the rest of the day as
The body is quite an ingenious instrument and should be
handled with care!