title: Introducing novel approaches for examining the variability of individuals' physical activity.
abstract: Tudor-Locke and colleagues previously assessed steps/day for 1 year. The aim of this study was to use this data set to introduce a novel approach for the investigation of whether individual's physical activity exhibits periodicity fluctuating round a mean and, if so, the degree of fluctuation and whether the mean changes over time. Twenty-three participants wore a pedometer for 365 days, recorded steps/day and whether the day was a workday. Fourier transform of each participant's daily steps data showed the physical activity had a periodicity of 7 days in half of the participants, matching the periodicity of the workday pattern. Activity level remained stable in half of the participants, decreased in ten participants and increased in two. In conclusion, the 7-day periodicity of activity in half of the participants and correspondence with the workday pattern suggest a social or environmental influence. The novel analytical approach introduced herein allows the determination of the periodicity of activity, the degree of variability in activity that is tolerated during day-to-day life and whether the activity level is stable. Results from the use of these methodologies in larger data sets may enable a more focused approach to the design of interventions that aim to increase activity.
authors.affiliation: a School of Health Sciences , University of South Australia, City East Campus , Adelaide 5001 , Australia.
authors.forename: Alex V
authors.initials: AV
authors.lastname: Rowlands
authors.forename: Sjaan R
authors.initials: SR
authors.lastname: Gomersall
authors.forename: Catrine
authors.initials: C
authors.lastname: Tudor-Locke
authors.forename: David R
authors.initials: DR
authors.lastname: Bassett
authors.forename: Minsoo
authors.initials: M
authors.lastname: Kang
authors.forename: François
authors.initials: F
authors.lastname: Fraysse
authors.forename: Barbara
authors.initials: B
authors.lastname: Ainsworth
authors.forename: Tim S
authors.initials: TS
authors.lastname: Olds
mesh_terms: D056044:Actigraphy; D000203:Activities of Daily Living; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D010507:Periodicity; D012107:Research Design; D014937:Work
keywords: FFT; pedometer; periodicity; season