four years, the average teenage boy will grow a foot taller, put on a stone of
muscle, drop an octave in the pitch of his voice and develop 40% more heart muscle.
start growing later than girls, but they are not entering puberty later. Rather,
their growth spurt comes at the end of puberty, not the beginning. This delay
gives boys the advantage of an extra two years of normal childhood growth before
their final growth spurt. This is one of the reasons why adult men are on average
13cm taller than women.
reason for their height is that boys grow faster than girls at their peak rate.
They grow faster because they have higher levels of testosterone in their bloodstream
than girls. The testicles release more and more testosterone into the blood stream
as they mature. During puberty an average boy's production of testosterone will
triggers cells all over the body to grow. The skeleton grows in much the same
way as in girls, with the arms and legs growing ahead of the torso. But the bones
become much denser and heavier than in girls. The final phase of skeletal growth
in boys is a broadening of the chest and shoulders. This generally finishes around
the age of 20.
triggers cells all over the body to grow
muscles go through a phase of rapid development which girls miss out on. Our muscles
are made up of fibres. At puberty in boys, these fibres don't increase in number,
but the length and width of existing muscle fibres increases.
increases the amount of haemoglobin carried in red blood cells. Haemoglobin is
the oxygen-carrying red pigment in red blood cells. Higher levels of haemoglobin
enable red blood cells to deliver more oxygen to muscles. This oxygen is used
to create energy for muscles to exercise. As a result, teenage boys become fitter
and stronger than they have ever been before.
testosterone levels start to surge inside a boy's body, other things also begin
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