London, June 22 (IANS): Child fitness levels are falling at an even faster rate than earlier feared - and this time there is evidence it has nothing to do with obesity, shows a study.

The study follows the 2009 study that showed child fitness declined by eight percent over the previous 10 years.

Now, researchers have reported an even larger drop in fitness in school children.

The children who they tested were actually thinner than those measured in 2008.

"Our results show there is no obesity crisis in the schools we went to as less than five percent 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," said lead researcher Gavin Sandercock from the University of Essex.

The team studied over 300 students aged 10 and 11 who took part in the study.

They expected that children with a lower BMI would do better than the heavier children they measured six years ago.

"But despite finding a lower average BMI in the children measured in 2014 than in 2008 we found the children still could not run as fast, showing they had even lower cardiorespiratory fitness."

"Our study has shown that this continued reliance on BMI as the stand-alone measurement of child health does not tell us enough about health," he said.

"Lower BMI values could be due to children eating less or more, or it could be that one group is taller."