A LITTLE exercise would make a big difference to today鈥檚 children. Many are
failing to build up their skeleton during a vital two-year window before
puberty, making them much more likely to break bones later in life.
Heather McKay of the University of British Columbia in Vancouver has shown
that children have the greatest increase in bone mineral after the growth spurt
just before puberty. Children put on over a quarter of their bone mass in this
two-year period, she and a colleague found. In girls, it tends to be between age
10 and 12, while in boys it鈥檚 between 13 and 15.
Now McKay鈥檚 team, which is following 383 children aged 8 to 13 for three
years, has found that even small interventions during this period can make a big
difference. The researchers asked half of their volunteers to do a circuit
training programme lasting 10 minutes just three times a week. Children in this
group have to skip and do box jumps, side-to-side jumps and other high-impact
exercises. Other children spend the same amount of time doing stretches and
warm-ups.
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After a year, the girls doing circuit training had amassed an extra 2 per
cent of bone mineral compared with the stretchers. After two years, they were
ahead by 5 per cent. The results on boys are still being analysed.
While the results show that exercise clearly pays off, McKay laments that a
third of all Canadian children are not active for even 10 minutes a week. We
lose a quarter of our bone mass as we age. Whether this seriously weakens our
bones largely depends on how much we build them up in childhood. 鈥淚f we can
increase bone mass by 10 per cent by adulthood, we can decrease the incidence of
fractures by 50 per cent,鈥� says McKay.
Graham Fishburne of the University of Alberta in Edmonton hopes the study
will help persuade parents and teachers that physical education is important.
鈥淲e can make a difference,鈥� he says.
But the way physical education is taught in schools may have to change.
Children need real physical skills, not just a few games of dodgeball a week.
鈥淭here鈥檚 been a huge deterioration,鈥� he says, referring to the inactivity caused
by computers, television and gaming. 鈥淵es, there have always been bookworms, but
they still had to go to the library and carry the books home.鈥�