AS one of Scotland's health-promoting schools, Knightswood secondary in Glasgow has tried to reinforce messages about diet and lifestyle in a number of ways.

The school is a centre of excellence for dance and, as well as offering specialist training to exceptional students, about 100 mainstream pupils attend dance clubs.

Sybil Simpson, the headteacher at the school, said all participated with ''gusto,'' improving both their physical and mental well-being.

She said, however: ''If you suggested to them doing 10 laps round a sports field they would not be so keen.''

Mrs Simpson admitted it was still difficult to enthuse all pupils about healthy eating and exercise. Despite the enthusiasm shown at Knightswood secondary she was not surprised by the Health Behaviour in School-Aged Children study which showed more than three-quarters of 15-year-old girls in Scotland were not undertaking enough physical activity for a healthy life and more than half of all boys of the same age were also failing to meet Scottish Executive guidelines on the level of weekly exercise.

''When girls get into later teens - 19, 20, 21 - quite a number return to things like aerobics, but there definitely comes a point between the age of 14 and 18 where they go right off physical activity,'' she said.

Eilidh Ibbotson, a 15-year-old, from Alexandria, West Dunbartonshire, said her father had tried to encourage her to join a raft of different sports clubs but she had resisted.

''Sometimes I just can't be bothered,'' she said. ''Sometimes it intimidates me going to meet new people as well, especially if they have all been doing it longer than me.''

Eilidh, who spends two-and-a-half hours exercising a week, said sitting in lessons ''dripping'' after swimming and running around outside in shorts on cold days also made her ''loathe'' physical education sometimes.

Mary Allison, Scotland's physical activity co-ordinator, is driving forward a four-cornered strategy to tackle ''couch potato'' culture in Scotland which involves schools, communities, work places and homes. By 2006, she foresees a network of active school co-ordinators ensuring all schools are promoting active lifestyles in numerous different ways.

She said: ''The physical activity taskforce work is really beginning. Over the next 10 to 12 years we would like to see more of a difference. It is a real shift in society we are calling for.''