Current recommendations for children to exercise an hour every day are "insufficient" to protect them from heart and blood circulation problems later in life.
Children under 10 years of age need at least 80 minutes of physical activity a day to keep them healthy, including 20 minutes of vigorous exercise, conclude researchers publishing in the journal BMC Medicine.
This new research into the links between exercise in younger children and the risk of developing cardiovascular disease (CVD) in adulthood is part of the European Commission-sponsored project known as IDEFICS (identification and prevention of dietary - and lifestyle - induced health effects in children and infants).
The IDEFICS consortium was set up to address the epidemic of obesity and ill-health affecting Europe's young people, and it comprises 24 research centers and companies across Europe.
Exercise is known to reduce the risk of CVD, but current guidelines for children are based on youngsters over 10 years old. Until now, it has been unclear what children under 10 need.
The study team, led by David Jiménez Pavón from the University of Zaragosa, is the first to look at the link between physical activity and cardiovascular risk in these younger children.
The researchers calculated the risks of CVD by looking at factors such as blood pressure, cholesterol levels and skin folding in a study group of 3,000 children aged between 2 and 9 years.
Their findings are bad news at almost every level: around 15% of the kids had a heightened CVD risk. Unhealthy profiles were spotted even in very young children, aged under 6 years.
Boys and girlsThe risk profiles differed with age and between boys and girls, so the team recommends age- and gender-specific guidelines. Boys under 6 years old need more than 70 minutes of moderate-to-vigorous exercise a day, whereas older boys need at least 80 minutes. Girls of all ages need around an hour of exercise.
These findings go further than previous general guidelines that recommend kids get around an hour of daily moderate-to-vigorous exercise to improve health. They also highlight the inappropriateness of a "one-size-fits-all" approach. Some children meet the previous guidelines yet still have unhealthy CVD profiles.