12
ISSUES: Fitness & Health
Chapter 1: About fitness
Poor fitness is a bigger threat to child health
than obesity
An article from
The Conversation
.
By Gavin Sandercock, Reader in Sports Science (Clinical Physiology),
University of Essex
T
he least fit ten-year-old English
child from a class of 30 in 1998
would be one of the five fittest
children in the same class tested today.
These are the worrying findings of a new
piece of research that has crystallised
the need to focus on a sharp decline in
fitness levels, not obesity, when it comes
to improving children’s health.
Back in 2009, we reported an 8% decline
in fitness of ten-year-old children from
the borough of Chelmsford, Essex. At
the time this was twice the global rate
of fitness decline. The story got a lot of
media attention and then chief medical
officer Liam Donaldson proposed the
introduction of fitness assessments
to monitor children’s health. But
unfortunately he resigned his post
soon after and following a change in
government, nothing happened and all
went quiet. Until now.
This year, the trade body UK Active
published its
Generation Inactive
report
which contains five recommendations
to improve children’s health through
physical activity. One of these
is a repeated call to use fitness
measurements to follow trends in
physical activity, evaluate trials and tell
us more about our children’s health.
The next day our follow-up to the 2009
study was published. By testing another
300 ten-year-olds six years later, we
confirmed two things. First, there simply
is no obesity epidemic – at least not in
the schools we visited. Less than 5% of
pupils were obese and the average body
mass index (BMI) was below 1998 values.
This might have been a good news story
if BMI was all we had measured; but our
fitness test results told a different story.
Thinner, but less puff
A drop in BMI tells us only that the
children are “thinner” but tells us
nothing about what caused this change.
BMI could be lower due to decreased
energy intake (food), due to increases in
energy expenditure (exercise), or both.
One thing we do know is that children
with a lower BMI usually do better on
the 20m shuttle run used to test their
fitness in this experiment because being
lighter makes it easier to run and turn.
Based on their BMI, we predicted that
our 2014 sample would out-perform
the relatively heavier children we had
measured six years ago.
Yet despite a lower BMI, the 2014 children
still couldn’t run as fast as their classmates
from2008. The overall rate of declinewas
0.95% per year; faster than the 0.8% per
year decline from 1998–2008.
Fitness has been declining even faster
over the past six years than in the
decade before. Girl’s fitness fell at twice
the global average but our data showed
boys’ fitness is declining three times
faster in England than it is in the rest of
the world.
Analysing pupils’ actual test performance
(how many shuttles they run) shows just
how big the fall in fitness from 1998 to
2014 is. In 1998, the average boy ran 60
shuttles (1.2km) before stopping; in 2014,
they ran only 33 (660 m). To put this in
context, in 1998 the average boy could
run a mile in seven minutes 50 seconds
but it would take boys today nine
minutes and 40 seconds. That’s nearly
two minutes slower. Girls are also one
minute 40 seconds slower than in 1998,
and it would now take the average girl
over tenminutes to cover a mile.
Our fitness data also told us why
the BMI had gone down. By process
of elimination, it could not be that
children were expending more energy
by being more active as this would
have improved, or at least maintained
their cardiovascular fitness. Instead,
combining our BMI and fitness findings
told us that children are eating less and
doing less exercise.
Low activity levels won’t come as a
surprise: national surveys repeatedly
show an inactivity pandemic; however,
the idea that children are eating less
might. We purchase around 30% fewer
calories today than 20 years ago and
there is evidence we’ve been eating less
and less since the1970s. Given the current
hysteria over sugar it’s worth mentioning
that as well as eating less, the percentage
of calories children get from sugar has
also declined since the 1990s
BMI isn’t everything
English childhood obesity figures
reported in the press mostly originate
from the National Child Measurement
Programme (NCMP). The way these
figures are reported artificially inflates
the obesity problem for two reasons.
First, the NCMP itself uses a rather out-
dated definition of obesity (which is not
even allowed in some scientific journals).
Second,
headline
figures
usually
combine ‘overweight’ and ‘obese’ BMI
categories. Overweight is not a health
problem, there is growing evidence that
adults with a BMI classed as overweight
are the most healthy.
Our study has shown that this continued
relianceonBMI as the lonemeasurement
of child health is not working. Yet again,
we find ourselves calling for a rethink on
how we monitor children’s health.
We agree with UK Active that there is
an acute need to increase the physical
activity levels of young people. Yet
activity itself is notoriously difficult
to measure. Fitness is the single most
important indicator of someone’s
health and can be measured safely
and objectively in the general
population. Perhaps most importantly,
and unlike weight or BMI, fitness is
very sensitive to changes in physical
activity behaviour. You may know (or
be) someone who has found it hard
to lose weight, but have you ever met
anyone who didn’t get any fitter when
they started exercising?
