Adolescents who replaced just 30 minutes of sedentary behaviors each day with moderate-to-vigorous physical activity or sleep may lower their insulin resistance, a key factor in preventing the development of Type 2 diabetes, according to preliminary research presented at the American Heart Association's EPI|Lifestyle Scientific Sessions 2026. The findings indicate that public health initiatives promoting physical activity or sleep rather than sedentary activities could help preserve cardiometabolic health among teens in the U.S.
The study analyzed health data from 802 participants in Project Viva, a long-term study of the health of women and children in Eastern Massachusetts. Researchers found that adolescents spent 48% of their daily time, or 11.5 hours per day, in sedentary activities such as sitting in class, doing homework, commuting, and screen time. In contrast, only 2% of their day was dedicated to moderate-to-vigorous physical activity like running, swimming, or playing basketball.
"I was happily surprised with the strength of the association of replacing 30 minutes of sedentary time with moderate-to-vigorous physical activity - a 15% lower insulin resistance is quite a big change," said Soren Harnois-Leblanc, Ph.D., R.D., lead author of the study. The research showed that substituting 30 minutes per day of sedentary time with moderate-to-vigorous physical activity reduced a measurement of insulin resistance by nearly 15%, while replacing sedentary time with sleep lowered insulin resistance by nearly 5%.
The American Heart Association's Life's Essential 8 metrics for optimal cardiovascular health include strategies for incorporating healthy lifestyle into daily life. For example, dimming lights before bedtime, creating a nighttime routine that doesn't include electronic devices with screens, and putting the phone on "do not disturb" can help improve sleep quality and quantity. Integrating physical activities with social time with friends can make exercise more appealing than sedentary activities.
"This study shows that young adolescents spend a lot of their day being sedentary and only a small amount of time being physically active," said Kershaw Patel, M.D., an American Heart Association volunteer. "Interestingly, teens who had more moderate to vigorous physical activity early in adolescence showed signs of lower insulin resistance later on. The big takeaway is being active early in life can really make a difference for long-term health."
While the study did not find an association between more time spent in light physical activity and lower insulin resistance, investigators urge additional research on this topic. "More time spent in light physical activity may be beneficial to prevent cardiometabolic disease in adults. Light physical activity is an interesting target because it is likely easier to integrate into everyday routines," said Harnois-Leblanc.
The study had some limitations, including that insulin resistance information in late adolescence was available for only 49% of participants who had accelerometer data collected in early adolescence. Additionally, cause-and-effect for daily activities and insulin resistance cannot be proven by this data analysis. The findings are considered preliminary until published as a full manuscript in a peer-reviewed scientific journal.
For more information on physical activity recommendations, visit https://www.heart.org/en/healthy-living/fitness/fitness-basics/aha-recs-for-physical-activity-in-adults. Additional resources on youth activity can be found at https://www.heart.org/en/healthy-living/fitness/fitness-basics/how-can-i-help-my-child-be-more-physically-active.
