Conducted by researchers from the Peninsula Medical School in Plymouth, UK, the EarlyBird study has followed the development of over 200 children in Plymouth born in 1995 and 1996.
At the age of five to eight years, 42 per cent of boys and only 11 per cent of girls were found to meet the government recommended daily exercise level of one hour of moderate exercise.
Also, the researchers found that exercise alone didn't have any positive effect on weight control over time, although the research team maintained that this does not qualify that exercise has no health benefits for children.
In fact, in comparison with peers who took less exercise, children who met the recommended activity levels fared better for blood pressure, cholesterol, triglycerides and insulin resistance, which is a recognised precursor to type 2 diabetes later in life.
But, still the researchers believed that improving children''s diets would be likely to have a greater impact on their overall health and weight.
They have claimed that the children's diets have "changed markedly" over the last two decades,
" We are keen to stress that children should be encouraged to be active, because our study showed that regular exercise improved metabolic health even without improving BMI," said Dr. Brad Metcalf, researcher in the Department of Endocrinology and Metabolism at the Peninsula Medical School.
The study was conducted on 212 children from 54 schools in Plymouth, with a follow up of four years. Once a year the children were tested by wearing small monitors that recorded their exercise levels.
The amount of physical activity achieved by children each day varied considerably - some only managed 10 minutes of moderate exercise, while others went over 90 minutes.
"The results for girls are in line with past research that shows that young girls do not exercise as much as boys. To some degree any child''s activity level can be affected by biology - some children are more naturally active than others and this might explain why there is such a marked difference between boys and girls. At present it is unclear whether exercise guidelines should be adjusted for this difference, or whether girls should be encouraged to exercise more," said Metcalf.
The research has been published in the most recent issue of the journal "Archives of Diseases in Childhood."