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Written by Helen Harris
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Your newborn's bones and muscles still have a great deal of developing
to do. Throughout childhood and adolescence, your infants bones and
delicate muscles undergo a constant process of growth and remodeling.
By the age of 17 when around 90 per cent of the final bone mass is
present, bones are as strong as iron and around three times as light.
Your child's bones are still rubbery at birth because the process of
ossification, the hardening and calcification of soft tissue into bone,
is not yet complete. Soft bones make it easier for your baby to squeeze
through the birth canal and provide the potential for further growth,
essential as the child grows bigger and taller. Not until their early
twenties do the ends of their bones finally harden, permanently fixing
the length of the bone and therefore their height.
Bone Density
This is not to say that bones no longer continue to develop after
childhood - they grow thicker or thinner or change in density
throughout life in response to the effects of diet and exercise.
However, bone density during childhood goes a long way to determining
peak density in later life: for every 5 per cent increase in bone
density during childhood and adolescence, the risk of developing
osteoporosis or fracturing a bone in later life drops by as much as 40
per cent. For this reason it is vital to ensure that your child gets
plenty of exercise and all the nutrients required to build strong bones.
Puberty
The most dramatic increase in height and bone length occurs at puberty
with a sudden growth spurt that lasts 2 - 3 years. Some children grow
10cm (4in) in a year during puberty. The growth spurt is related to the
production of sex hormones such as testosterone, progesterone and
estrogens, which stimulate the growth of bone, muscle and other body
tissues.
These hormones also play a role in the fusion of the growth plates that
heralds the end of bone growth. Boys tend to have a growth spurt later
than girls, around the age of 10-15 years compared to 8-13 years in
girls. This gives boys time to grow taller and larger before the growth
plates fuse.
Factors affecting good growth
A child's potential for growth is determined by genes inherited from
both parents. But a number of other factors can influence whether this
maximum potential is reached, including general health, nutrition and
emotional well-being.
Sometimes growth is affected by a specific disease or disorder.
Examples include hormonal disorders (such as a lack of growth hormone
or an under active thyroid), long-term illnesses such as a chronic
kidney failure and genetic disorders. These types of growth conditions
are rare, however. The most important way to help your child form
healthy bones and muscles is to encourage a healthy diet and lifestyle.
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