A new study led by a University of North Carolina researcher reinforced that regular physical activity and less sedentary behavior reduces the risk of mortality.
[Photo: Dr. Kelly Evenson]
The study, which appears in the February issue of the American Journal of Preventive Medicine, used an accelerometer to assess participants’ physical activity and sedentary behavior. The accelerometers were similar to many digital activity trackers, but did not provide feedback to the participants. When the participants wore the accelerometers over a weeklong period, researchers were able to derive their physical activity and sedentary behavior every minute for that week. This allowed for a detailed description of their activity patterns.
“The advantage of accelerometers is that they provide detailed information on movement that is very challenging to self-report,” said Dr. Kelly Evenson, research professor in the Department of Epidemiology at UNC’s Gillings School of Global Public Health. “We can take the information from the accelerometer and assign the amount of time each participant spends in light, moderate or vigorous physical activity, as well as sedentary behavior. From this, we can find patterns of physical activity and sedentary behavior, which is important when trying to build a more comprehensive understanding of the participant’s approach to movement.”
Dr. Evenson added that previous studies using accelerometry had explored only the accumulated time spent in various intensity levels, but not the day-to-day patterning. She and her fellow researchers wanted to know if quantifying daily pattern of physical activity and sedentary behavior would reveal if certain patterns had beneficial or detrimental effects on all-cause mortality.
“We found adults who engaged in patterns of daily activity, as well as adults who were ‘weekend warriors’ whose activity occurred primarily for a few hours during weekends, both had a reduction in mortality risk,” Dr. Evenson said. “Conversely, people who engaged in little or no activity showed the highest risk of all-cause mortality.”
In addition, adults with the highest bouts of sedentary behavior (for example, sitting for lengthy periods of time without moving) had an increased risk of mortality.
The study, “Accelerometry-Assessed Latent Class Patterns of Physical Activity and Sedentary Behavior With Mortality,” included 4,510 U.S. National Health and Nutrition Examination Survey participants ages 40 years and older enrolled in 2003–2006 with follow-up through 2011. For one week, participants used hip-worn accelerometers, which provided minute-by-minute information on physical activity and sedentary behavior. During an average of 6.6 years of follow-up, 513 deaths occurred.
Dr. Evenson and fellow researchers, Dr. Amy Herring, Carol Remmer Angle Distinguished Professor of Children’s Environmental Health and associate chair of biostatistics, and Ms. Fang Wen, a programmer in epidemiology at the Gillings School, hope the study will provide additional evidence for national physical activity guidelines on the associations between physical activity, sedentary behavior and all-cause mortality.
Dr. Evenson said the data generated also offers opportunity for further examination in a few years to see if the trends found in this study continue as observed.
The full study can be found here.