Health risks for teens as they swap exercise for slumping on the sofa

Cancer Research UK

Britain’s teenagers are endangering their health by cutting back on exercise and spending more hours watching TV and playing computer games according to a new study* by Cancer Research UK.

Researchers studied nearly 6,000 11-12 year olds at 36 London schools and tracked their physical activity and sedentary behaviour over a five-year period.

They found that physical activity declined in girls by 46 per cent and in boys by 23 per cent over five years.

Lack of vigorous activity and too much sedentary behaviour in adolescence can lead to becoming overweight or obese in adult life which in turn increases the risk of heart disease, cancer and diabetes.

Girls increased their sedentary behaviour by 2.8 hours a week while in boys the increase was 2.5 hours a week. By age 16, girls were physically active on less than two days a week and boys for just over three days a week.

The study, funded by Cancer Research UK and supported by the British Heart Foundation also showed that Asian adolescents were less active than white adolescents while black adolescents were the most sedentary.

Students were asked how often they carried out vigorous exercise that made them sweat and breathe hard. They were also asked how many hours they watched TV, played video games and sat in front of a computer.

By the age of 16 the average time screen time was 16 hours a week. But this varied among different social groups. Youngsters from more deprived neighbourhoods reported 17.2 hours a week of screen time compared with 15.6 hours for those from more affluent areas.

Lead author Professor Jane Wardle, director of Cancer Research UK’s health behaviour unit at University College London, said: "The study showed marked reductions in physical activity and increases in sedentary behaviour between the ages of 11- 16. The trends were particularly notable in girls. There is growing evidence about the role that physical activity and a healthy weight play in reducing our cancer risk. The results of this study highlight the need for adolescents to be given opportunities, encouragement and support to take more physical activity to benefit their future health. Schools and parents both have roles to play in encouraging children to be more active by providing more physical education and limiting time for TV and computer games. Non-traditional forms of exercise like aerobics or dance classes might increase appeal to girls. Walking and cycling should also be promoted."

Professor John Toy, medical director of Cancer Research UK, said: "While computers and TV can bring many educational benefits and enjoyment to young people there is a danger in them spending too much time sitting in front of a screen at the expense of exercising. Adolescents are more likely to develop into healthy adults and will reduce their cancer risk if they grow up taking regular exercise like going for a run in the park or cycling."

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Notes to Editor

The results of this research are part of a larger study looking at all aspects of health, behaviour and social background in adolescents and how this relates to future cancer risk: The Health and Behaviour in Teenagers Study (HABITS)

Half of all cancers could be prevented by changes to lifestyle. Cancer Research UK’s Reduce the Risk campaign has five simple messages to help people reduce their risk of cancer. These are:

  • Stop smoking: this is the best present you will ever give yourself
  • Stay in shape: cut your cancer risk by keeping a healthy weight
  • Eat and drink healthily: limit alcohol and maintain a healthy diet
  • Be SunSmart: protect yourself from the sun and harmful UV
  • Look after number one: be aware of any body changes and go for screening when invited.

For further information on Reduce the Risk click here

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