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| Teenage girls tend to be less active than boys |
Obesity has a greater impact on the blood pressure of teenage girls than on teenage boys, a US study has suggested.
High blood pressure is a risk factor for heart disease and stroke in later life.
The study of 1,700 teenagers, presented to the American Physiological Society conference, found girls had three times the risk of higher blood pressure.
A British Heart Foundation spokeswoman said a third of young people in the UK were overweight or obese.
The teenagers, aged between 13 and 17 had their blood pressure measured as part of school district health surveys and health checks. Their body mass index (BMI) - a measure of weight/height ratio - was also recorded.
There are two types of blood pressure which are measured. Diastolic pressure - the lower number in a reading - measures the force on the arteries between heartbeats. Systolic blood pressure, represented by the top number in a blood pressure reading, is the amount of force that blood exerts on blood vessel walls when the heart beats.
High systolic measurements indicate risk for heart disease and stroke.
It was found obese boys were 3.5 times more likely to develop elevated systolic blood pressure than non-obese boys.
But similarly obese girls were nine times more likely to develop elevated systolic blood pressure than their non-obese peers.
Danger 'highlighted'
The researchers from the University of California say the link may be counteracting the known protective effect of the hormone oestrogen on the heart.
Dr Rudy Ortiz, who led the study, said: "Overall, there is a higher likelihood that those who present with both higher BMI and blood pressure will succumb to cardiovascular complications as adults.
"But the findings suggest that obese females may have a higher risk of developing these problems than males."
Dr Ortiz said the significant difference between boys and girls could be explained by exercise levels.
"Obese adolescent females participate in 50 to 60% less physical activity than boys in the population surveyed."
Natasha Stewart, senior cardiac nurse at the British Heart Foundation, said: "Here we have yet more evidence highlighting the danger that obesity poses to the health of our children.
"Based on this American study alone, it's too early to say for sure whether girls are more at risk than boys, but we do know girls tend to be less active than boys which could play a part.
"What is certain is that obesity is clearly putting both boys' and girls' health at risk.
"This is a very real problem for lots of families - about a third of young people in England are now overweight or obese.
"Healthy eating and physical activity during childhood is vital to ensure growth, development and a pattern of healthy habits which will carry through into adulthood."
