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The purpose of this study was to examine the relationship between 2005−2006 National Health and Nutrition Examination Survey (NHANES) accelerometer-determined steps/day and activity counts/day, and between steps/day and estimates of nonwear time (as an indicator of the unmonitored day) and time spent in sedentary behaviors as well as a range of physical activity intensities.
Linear regression models were used to characterize the relationship between steps/day, activity counts/day, estimates of wear time, and intensity categories.
1781 males (mean age = 46.5 years) and 1963 females (mean age = 47.7 years) wore accelerometers 14.0 ± SEM0.06 hours/day. The relationship between steps/day and activity counts/day was positive and strong (R2 = .87). The relationship between steps/day and time spent in sedentary behaviors was inverse and moderate (R2 = .25). Stronger and positive relationships were apparent between steps/day and time in light (R2 = .69) and moderate (R2 = .63) intensity activities. There was no discernable relationship between steps/day and time spent in low or vigorous intensity activities or with wear time.
Assessed by accelerometer, steps/day explains 87% of the variation in activity counts/day, 25% of the variation in time in sedentary behaviors, 69% of time in light intensity, and 63% of time in moderate intensity.
Tudor-Locke is with the Walking Behavior Laboratory, Pennington Biomedical Research Center, Baton Rouge, LA. Johnson and Katzmarzyk are with the Dept of Population Science, Pennington Biomedical Research Center, Baton Rouge, LA.