Now it appears that the best way to prevent osteoporosis is to ensure sufficient bone density is built up before the onset of puberty, after which the body's ability to build up bone density declines.

Exercise physiologists at the University of Wales, Bangor's School of Sport, Health and Exercise Science, have for the first time proven a strong link between children's bone density and the number of steps or movements taken per day.

This correlation has been found in athletes and gymnasts, where the effects of their specialist training on their bone density has been measured.

This is the first study to link bone density in children with their individual physical activity, measured by a pedometer. It underlines the importance of good levels of physical activity for maintaining bone density as well as for general good health and well being.

"It appears that the key to preventing osteoporosis in the population begins in childhood," said Ann Rowlands, lecturer in physiology at the School of Sport, Health and Exercise Science.

"Our research shows a clear link between those children who had the higher rates of physical activity and greater bone density. Although bone density levels were higher for boys, the boys and girls who recorded the highest levels of physical activity also had higher levels of bone density. The difference between those with low bone density and those with the optimum levels of bone density can be described as 35 minutes of walking or 25 minutes of energetic exercise."

"This exercise need not be taken in one period. It represents activity over a whole day. A change to walking to and from school or replacing one television programme or one video game with 35 minutes of energetic children's activities could be sufficient to build up healthy bone density," said Rowlands.

Local school children aged 8-11 took part in the survey. They wore a simple pedometer inside a 'bum bag' for a week. This directly measured their daily activity rates, measuring all their walking and running movements. The children also kept a food and drink diary over four days and had their bone density measured on specialist equipment at the School of Sport, Health and Exercise Science.

The survey also revealed the following:

• Boys are 25% more active than girls;

• Boys have a 25% higher calcium intake than girls, although the boys only just reached the national guidelines for calcium intake for 8 year olds and did not reach the guidelines for 10 year olds;

• The girls in the study did not reach national guidelines for calcium intake;

• The boys' bone density was 12% higher than the girls;

• In comparing bone density the survey took body size, sex and calcium intake into consideration.

The research was conducted by PhD student Sarah Maley Powell under the guidance of Ann Rowlands and Dr. Roger Eston of the School of Sport, Health & Exercise Science. A paper based on the research is to be presented at the International Symposium of Paediatric Work Physiology in Belgium in September.

[Contact: Dr. Ann Rowlands]

04-May-2001