Counts for nonwear minutes were set to missing, as were those for spurious data, defined either as counts per minute of at least 30,000 or at least 10 minutes of the same repeated nonzero counts. Nonwear time was defined as a period of 60 minutes or more when the accelerometer recorded zeros, with allowance for 1 or 2 minutes of counts between 0 and 100, as recommended elsewhere ( 7, 15). Participants did not keep a diary of when the monitor was put on and taken off. Participants received $40 upon return of the accelerometer by mail. They were also told to remove it at bedtime. It was not waterproof, so participants were asked to remove the monitor when showering or engaging in water activities such as swimming. It was strapped to an elastic belt and worn over the right hip. The instrument recorded 1-minute intervals starting at midnight after the examination. From 2003 to 2006, ambulatory participants aged 6 years or older received an accelerometer at their examination to wear for 7 consecutive days ( 14). The ActiGraph is a technically reliable instrument, able to detect differing levels of intensity ( 12, 13). The instrument converted acceleration sampled multiple times to a digital signal, which was stored as a count. NHANES used the ActiGraph model AM7164 (ActiGraph, LLC, Fort Walton Beach, Florida) to measure acceleration. NHANES conducts in-home interviews, in English or Spanish, using a computer-assisted personal interview system, and physical examinations at a mobile examination center. To produce reliable estimates, the survey oversamples several population groups, including adults aged 60 or older. ![]() NHANES uses a complex, multistage probability sample of the civilian US noninstitutionalized population of all ages. To increase the stability of the estimates, we combined data from 2003 to 2006, the most recent accelerometer data available. For both aims, we report prevalence overall and by age group, sex, and race/ethnicity. The objective of this study was to use nationally representative data from NHANES for adults aged 60 or older to 1) describe MVPA and explore differences in prevalence depending on the cut point used to define MVPA and 2) describe sedentary behavior. Sedentary behavior among older adults has also not been well described. It is unclear why the differences between self-report and objectively measured physical activity by race/ethnicity persist with older age groups. It is unclear to what degree the difference in cut points may alter the reported prevalence of physical activity.Īnother intriguing finding of the 2005-2006 NHANES was that similar proportions of Hispanic adults (9%-10%) and non-Hispanic white adults (8%-10%) met physical activity guidelines when measurements were based on accelerometry ( 2) however, self-reported findings from the same populations indicated lower levels of physical activity among Hispanics (41%-44%) compared to non-Hispanic whites (63%-65%). One reason for the wide ranges is that some calibration studies focus mainly on ambulation to determine cut points ( 3, 6, 7), but others include lifestyle activities ( 5). For example, using the ActiGraph accelerometer, studies that included adults aged 60 or older recommended MVPA cut points ranging from 574 to 2,020 counts per minute ( 3, 5- 7). However, calibration studies report a wide range of cut points to define MVPA for older adults. Researchers often rely on calibration studies to determine the appropriate count cut point or cut points to identify intensity levels ( 4) of sedentary, light, moderate, or vigorous physical activity. Higher counts result from greater acceleration. An accelerometer is an instrument worn by study participants it detects acceleration in selected planes and converts the data into "counts," which are then measured in specific time intervals or epochs. This discrepancy may be due to overreporting of physical activity because of difficulty recalling activities, cultural differences in interpretation, social desirability bias, or the way the questions are worded ( 3).Īccelerometry is a way to objectively assess physical activity that overcomes many of the limitations of self-report. ![]() Prevalence estimates for the same population are much lower, however, if based on objectively measured physical activity using accelerometry only 9% to 26% of adults aged 60 to 69 and 6% to 10% of adults aged 70 or older met current US recommendations for physical activity ( 2). ![]() Self-reported data from the 2005-2006 National Health and Nutrition Examination Survey (NHANES) indicate that 60% to 63% of US adults aged 60 to 69 years and 47% to 51% of adults aged 70 or older met current US recommendations for physical activity ( 1, 2).
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