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, based on an analysis of health data from Project Viva, indicate that public health initiatives promoting physical activity or sleep over sedentary activities could help preserve cardiometabolic health among teens in the U.S.
The study examined health data from 802 participants, with a median age of 12.9 years, who wore wrist accelerometers for 7-10 consecutive days and completed sleep logs. Researchers found that nearly half of a typical adolescent's day, 48% or 11.5 hours, was spent in sedentary activities like sitting in class, doing homework, commuting, or engaging with screens. In contrast, only 2% of daily time was dedicated to moderate-to-vigorous physical activities such as running, swimming, or playing basketball.
Using statistical modeling, investigators estimated the impact of substituting 30 minutes of sedentary time with other activities on insulin resistance levels measured in late adolescence. The results showed that replacing sedentary time with moderate-to-vigorous physical activity could lower the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) score by nearly 15%. Exchanging sedentary time for sleep was associated with a nearly 5% reduction in insulin resistance. However, shifting sedentary time to low-intensity physical activity did not produce a significant change.
"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. "Our findings mean that switching from sedentary behaviors to moderate-to-vigorous physical activity or sleep, even if it is only a few minutes per day to start, was beneficial for health."
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 without electronic devices, and putting phones on "do not disturb" can help improve sleep quality and quantity. Integrating physical activities with social time can make exercise more appealing than sedentary activities. More information on these recommendations is available at https://www.heart.org/en/healthy-living/fitness/fitness-basics/aha-recs-for-physical-activity-in-adults.
While the study did not find an association between light physical activity and lower insulin resistance, researchers noted that more time spent in light physical activity may be beneficial for preventing cardiometabolic disease in adults. "Light physical activity is an interesting target because it is likely easier to integrate into everyday routines," Harnois-Leblanc added.
The research has limitations, including that insulin resistance information in late adolescence was available for only 49% of participants who had accelerometer data collected earlier. Additionally, the analysis cannot prove cause-and-effect between daily activities and insulin resistance. The study is considered preliminary until published as a full manuscript in a peer-reviewed scientific journal.
"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."
The implications of this research extend beyond individual health outcomes to broader public health strategies. With Type 2 diabetes representing a growing health concern, particularly among younger populations, these findings suggest that relatively small, achievable changes in daily behavior could have significant protective effects. The study underscores the importance of creating environments and policies that make it easier for adolescents to replace sedentary time with more active or restorative behaviors, potentially reducing the future burden of metabolic diseases.
