New York City is one of the most walkable cities in the nation, providing many opportunities for physical activity, and New Yorkers are more likely to exercise regularly than the average U.S. adult - but instead they are also sitting far more than what is considered healthy.
According to a new study published by the U.S. Centers for Disease Control and Prevention in its journal Preventing Chronic Disease, the average New York City resident sits more than seven hours a day--greatly exceeding the three hours or more per day that is associated with decreased life expectancy.
In what is the first population-based analysis of data on New Yorkers' sitting patterns, and one of the first such studies nationally, researchers from NYU Langone's Department of Population Health and the NYC Department of Health and Mental Hygiene found significant differences in sitting time among specific demographic groups. For example, average sitting time was highest among adults who were college educated, in higher income brackets and/or 65 years of age or older. In contrast, lower-income individuals, those with less education, Hispanics and foreign-born New Yorkers spent the least amount of time sitting, according to the study.
"Although more information is accumulating about the dangerous health effects of sitting--even if you exercise regularly--few studies have actually quantified how much time people spend in this position," said Stella S. Yi, PhD, MPH, lead author of the study and an assistant professor of population health at NYU Langone.
Dr. Yi and her colleagues used data collected as a part of the City DOH's Physical Activity and Transit Survey, which surveyed a population-based sample of 3,811 adults by telephone in 2010 and 2011. They analyzed the data to ensure it was representative of New Yorkers across all five boroughs. Respondents were asked how much time they spent sitting on average during the previous seven days, both during the day and in the evening.
Among the findings:
- At the lower economic end, individuals spent 6.3 hours per day sitting, while those with higher incomes spent 8.2 hours per day sitting
- College graduates spent 8.2 hours per day sitting, compared with 5.5 hours per day for those with less than a high school education
- Whites spent on average 7.8 hours per day sitting, African Americans spent 7.4 hours sitting, Hispanics spent 5.4 hours sitting, and Asian Americans spent 7.9 hours per day sitting
- Sitting time was highest in Manhattan, compared to other boroughs.
The authors also reported on a subset of 667 participants who for one week wore accelerometers, which measure acceleration of motion, to monitor how much time they were sedentary. The average daily sedentary time was 8.2 hours per day.
Dr. Yi points out that a possible reason this number was higher than the sitting time values from the survey study is because sitting is one of a few different types of sedentary behaviors, which also includes standing and lying down. Participants 65 years of age or older were sedentary for nearly nine hours per day. Sedentary and sitting times were statistically similar, confirming the validity of the self-reported data.
Sitting time is linked to death from heart disease and other causes, with life expectancy increasing by two years if adults reduced their sitting time to three hours per day. Individuals who exercise regularly but are still sedentary for several hours a day may be at greater risk for adverse health outcomes than their physical activity levels might suggest.
"Interventions for decreasing sitting time in the worksite and home are needed to improve health outcomes across all groups--not just those identified as having the longest sitting times," Dr. Yi says.
Although Dr. Yi believes that those who sit the most are probably employed in office jobs, she says it is important to recognize differences within racial and ethnic groups.
"Whites and Asian Americans have the highest sitting times, but Asian Americans tend to hold occupations at both ends of the socioeconomic spectrum," she points out. "For example, Asian Americans hold both desk jobs and jobs in commercial settings like nail salons that offer little opportunity for reducing sitting time."
Dr. Yi concludes that "specific public health activities to reduce sitting time should consider cultural and socioeconomic differences, sex, and age, as well as the time of day the sitting is occurring, particularly given the diversity in New York City."