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Light intensity activity may help reverse damage from being sedentary, according to a new study.
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Childhood inactivity may be increasing risk for heart disease later in life, according to new research.

The time kids spend being sedentary may be correlated with an increase in the mass of the heart’s left ventricle — particularly in girls, according to research that will be presented this week at the European Society of Cardiology’s ESC Congress 2023 in Amsterdam.

“An enlarged heart is an objective indication that the heart is probably overworked in response to a stressful situation,” said lead study author Dr. Andrew Agbaje, principal investigator of the Urfit-child research group at the University of Eastern Finland’s School of Medicine.

The data was collected from the Children of the 90s study, one of the world’s largest cohort studies that measures lifestyle. The longitudinal study included 766 children and looked at data from ages 11 to 24, the research showed.

The children had worn activity monitors for one-week periods at several ages throughout the study.

At 11 years old, the children were sedentary for about six hours a day. At adolescence four years later, that rose to nearly eight hours a day and then to nearly nine by the end of the research period, according to the poster.

“It is important to note that the increase in sedentary time was ‘stolen’ from the time spent in light-intensity physical activity which reduced from 6 hours/day in childhood to 3 hours per day in young adulthood,” Agbaje said in an email.

More sedentary time was associated with increased left ventricle mass in the girls who were followed in the study, according to the new research. And higher mass of the left ventricle is a strong predictor of cardiac events in adulthood.

“Since it is rare for children to have heart attacks, left ventricular hypertrophy or enlarged heart has been employed as early signs of heart damage,” he said.

The data only showed the association in girls in this study, but more research with a larger group may show a difference for both boys and girls, Agbaje added.

“What’s most important about this study is it highlights the toll that sedentary behavior takes on our health, particularly to our heart health,” said Dr. Nieca Goldberg, the medical director of Atria New York City and clinical associate professor of medicine at New York University’s Grossman School of Medicine. Goldberg was not involved in the research.

The things we still don’t know

It is important to note that the new study has not been fully released — only a poster of the research, said Dr. Andrew Freeman, director of cardiovascular prevention and wellness at National Jewish Health in Denver. Freeman was not involved in the research.

And although the data showed an association between sedentary time and a predictor for heart disease, it is hard to say exactly how it manifests, Freeman said.

“I just don’t know if you can definitively say that there’s a certain threshold of left ventricular mass that correlates directly with a specific health outcome,” he said. “It’d be nice to follow these kids for another 13 years and see if they develop hypertension, which I suspect they will.”

Although this study has a modest sample size and is still preliminary in its findings, it is a good reminder to prioritize healthy behaviors in childhood, Goldberg added.

What your family can do to move more

The good news is that additional data from these researchers found that light-intensity physical activity has the potential to reverse the enlargement of the heart from sedentary time, Agbaje said.

“I would appeal to doctors and parents to encourage their children, patients, and clients to engage in light-intensity physical activity for at least 3 to 4 hours daily for a better heart condition,” he added in an email. “An example of such light physical activity is taking a long walk.”

Children ages 6 to 17 need about an hour of physical activity a day, according to the US Centers for Disease Control and Prevention. But a 2020 survey found that less than a quarter of students reached that metric.

When it comes to getting kids moving, focus on activities they enjoy, because that is what sticks, Goldberg said.

“If you’re somebody who has a fear of deep water, swimming may not be for you, right?” she said. “But walking, cycling, jogging, dancing, swimming — all of these things are great aerobic exercises and great exercises to bring about health benefits.”

If we want children to live not only long, but well — and without major health concerns — it is important to prioritize health now, Freeman said.

“The habits we form earlier in life and the way we live earlier in life have a lasting effect,” he said. “If we can figure out how to weave those habits into our lives earlier, the results will be amazing.”