Abstract 056: Normative Accelerometer-determined Steps/day from 6-85 Years of Age: NHANES 2005-2006
Introduction: Reference values used to interpret objectively monitored ambulatory activity (steps/day) represent summarized data collected with different instruments and protocols and aggregated across typically small, select, and disparate samples (e.g., sex composition and age groupings). A full distribution of nationally representative normative data presented by sex-age year collected using a single instrument and a standardized protocol is preferred. The purpose of this analysis of the 2005-2006 National Health and Nutrition Examination Survey (NHANES) accelerometer data is to provide smoothed (i.e., using LMS curve analyses) sex-age rankings from 6-85 years of age.
Hypothesis: We hypothesized that, across the lifespan, accelerometer-determined steps/day would be 1) higher in males than females; and 2) lower with higher ages.
Methods: Objectively monitored steps/day were measured using the ActiGraph accelerometer (model 7164) worn for 7 consecutive days. The analysis sample was comprised of 6,354 (51.8% female) individuals with valid accelerometer data (≤1 days with ≤10 monitored hours). Percentile values (25th, 50th, 75th, 95th) were computed for each single-year age by sex using the LMS method (LMS Chartmaker Pro Version 2.3). To avoid artificially creating sex/age differences through modeling procedures, the L, M and S parameters were chosen using the entire sample then applied to males and females separately to create the curves. Apparent differences by sex and age were noted.
Results: LMS curves for steps/day percentile values are presented in the Figure. Steps/day were higher for males than females at every age. A distinct pattern of incrementally reduced steps/day was apparent with higher age across the lifespan.
Conclusions: Sex and age are apparent modifiers of steps/day. These normative accelerometer-determined steps/day values can be used for multiple purposes including screening, program development and evaluation, comparison between populations, and tracking change.
- © 2013 by American Heart Association, Inc.