Child fitness levels are falling at an even faster rate than first feared - and it has nothing to do with obesity, according to a new study. Of more than 300 pupils aged between 10 and 11 who took part, the researchers expected that children with a lower BMI would do better than the heavier children they measured six years ago.

But the follow-up to a 2009 study showed child fitness declined by 8% over the previous ten years - yet the children they tested were actually thinner than those measured in 2008. 

Lead researcher Dr. Gavin Sandercock of the University of Essex explains, “Our findings show there is no obesity crisis in the schools we went to as less than 5% of pupils were obese and the average BMI is now below 1998 values. This would be good news if BMI was all we had measured, but our fitness tests tell a different story.

“Simply put, if you weigh less it is easier to run and turn so you should do better on our test. But despite finding a lower average BMI in the children measured in 2014 than in 2008 we found the children still couldn’t run as fast, showing they had even lower cardiorespiratory fitness. It has got to the stage now that if we took the least fit child from a class of 30 we tested in 1998, they would be one of the five fittest children in a class of the same age today.”

Fitness is an important indicator of child and adult health and any evidence of a decline in fitness is worrying, regardless of changes in BMI, stressed Sandercock. “Our study has shown that this continued reliance on BMI as the stand-alone measurement of child health doesn’t tell us enough about health.” 

In 2009, the team at Essex reported that English children’s fitness was declining at twice the global rate - 0.8% per year. These latest findings suggest fitness has been declining even faster over the past six years with an overall drop of 0.95% per year. This time boys’ fitness levels are falling much faster than girls.

Following the 2009 report on declining fitness, the then Chief Medical Officer Sir Liam Donaldson called for fitness testing, but no action was taken. Six years later UK Active launched their Generation Inactive campaign which just this week called for ‘An extension of the National Child Measurement Programme to include [assessments of] fitness’.

With the worrying further decline in child fitness levels, the Essex scientists are joining the growing group of professionals in public health, education and the health and leisure industry calling for a rethink on how we monitor children’s health.

“BMI doesn’t tell us very much about children’s health or lifestyle,” explained Dr Sandercock. “Lower BMI values could be due to children eating less or doing more, or it could be that one group is taller.

“Seeing fitness falling independent of BMI tells us for certain that the cause of the decline is a lack of physical activity. Being unfit and being obese are just two symptoms of physical inactivity that we can see – what we can’t see is the health problems building up in today’s unfit children.”

As well as introducing child fitness testing in schools Dr Sandercock would like to go further so we measure a child’s physical literacy – which includes fundamental movement skills such as running, hopping, throwing, catching and jumping - at each key stage just schools already do for subjects like numeracy and literacy.

“We think that formative physical literacy assessments involving simple tests of key skills and basic levels of strength, speed and stamina can tell us if primary school pupils are ‘physically literate’ enough so that they can go on to really get the best out of secondary PE,” added Dr Sandercock.