Sedentary time linked with enlarged hearts in teens
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Key takeaways:
- Increase in cardiac mass was three times greater in adolescents who were sedentary than in those who were physically active.
- Teen participation in physical activity may produce cardiac benefits.
Adolescents who were sedentary had greater increases in left ventricular mass than those who were physically active, according to a study published in the Scandinavian Journal of Medicine & Science in Sports.
“We decided to undertake this research due to the scarcity of accelerometer-measured physical activity and sedentary time with cardiac measures studies in adolescents,” Andrew O. Agbaje, MD, MPH, physician and clinical epidemiologist with the Institute of Public Health and Clinical Nutrition at the University of Eastern Finland, told Healio. “Particularly, the latest World Health Organization report did not recommend light physical activity due to the lack of evidence. Yet, it is known that over 80% of adolescents do not meet the average daily physical activity requirement. It is important to have evidence that would be useful for future physical activity guidelines.”
The analysis included 530 participants (50% girls) aged 17 years from the Avon Longitudinal Study of Parents and Children. Among boys, 17.9% had overweight/obesity and 11.6% had elevated BP/hypertension. Among girls, 24.5% had overweight/obesity and 1.1% had elevated BP/hypertension.
Average sedentary time was 468 minutes per day for boys and 484 minutes per day for girls, average light physical activity was 293 minutes per day for boys and 274 minutes per day for girls and average moderate-to-vigorous physical activity was 56 minutes per day for boys and 41 minutes per day for girls.
Sedentary time and LV parameters
According to the researchers, higher sedentary time was associated with higher left ventricular mass adjusted for height in girls (standardized beta = 0.16; P = .01) and was associated with lower LV diastolic function in boys (beta = –0.14; P = .04).
Higher levels of sedentary time and of moderate-to-vigorous physical activity were associated with higher LV mass regardless of weight, though the sedentary time-associated increase was three times higher than the moderate-to-vigorous physical activity-associated increase, the researchers found.
Light physical activity was associated with higher LV diastolic function in the entire cohort and in those without hypertension, and was linked to lower LV filling pressure in those with high lean mass, according to the researchers.
“These results were surprising, especially seeing that sedentary time of about 8 hours per day could increase heart size by 10%, while moderate-to-vigorous physical activity could increase heart size by 3%,” Agbaje told Healio. “The most important information is that light physical activity was not associated with a statistically significant increase in heart size, rather it was associated with better left ventricular diastolic function. It has been shown among adults that a 5 g/m2 increase in heart size could increase the risk of cardiovascular disease and death by 7% to 20%. Unfortunately, sedentary time in adolescents may increase left ventricular mass by 3.8 g/m2.7, which is a major public health concern.”
‘Encourage light physical activity’
Clinicians should “counsel adolescents to take a walk for at least 1 to 2 hours every day,” Agbaje said. “Especially those addicted to their phones, social media accounts, and video games, who spend a significant part of the day sitting or lying down. It does not appear that adolescents are willing to undertake a daily 60 minutes of moderate-to-vigorous physical activity on average per day as recommended by the World Health Organization, so doctors should encourage light physical activity.”
The findings have implications for public health policy, he added.
“The latest World Health Organization global physical activity report estimates that between 2020 and 2030, there will be over 250 million new cases of physical inactivity-related noncommunicable diseases attributable to hypertension alone,” he said. “Adolescents spend at least 7 hours per day sitting in school, thus increasing sedentary time from Monday to Friday. Perhaps the government could financially support schools to invest in ergonomic tables for students so that they receive every second lecture standing and walking on a spot, etc. This might be a better investment in prevention than treating hypertension, or physical inactivity-related cardiovascular diseases every year.”
For more information:
Andrew O. Agbaje, MD, MPH, can be reached at andrew.agbaje@uef.fi.
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