Gabe Mirkin, M.D.
Children need at least 90 minutes of exercise a day to
avoid heart disease when they are older, according to a new
study reported in Lancet (July 23, 2006). The old guidelines
recommending 30 minutes of exercise three times a week, or
even an hour a day do not appear to be adequate for preventing
obesity and heart disease. Researchers used heart rate
monitors to measure the activity of 1700 nine- to-fifteen-year-olds
in Denmark, Estonia, and Portugal. They then calculated a
heart-attack risk score consisting of blood pressure, cholesterol,
insulin resistance, and skinfold thickness.
They compared physical activity from the heart rate
monitors with the heart attack risk-factor score and found that the
more active the child, the lower the heart attack risk score. Many
children who exercised for 60 minutes a day were still overweight
and had high heart attack risk scores. The authors suggest that
the lack of regular physical activity is likely to mean that the
children are spending too much time watching TV, playing video
and computer games, and eating junk food. There is no reason
to expect that the results would be different with American
children. The current recommendation of at least an hour per
day of moderate activity in children may not be sufficient for
future heart health.
September 15, 2006