title: Assessment of minute-by-minute stepping rate of physical activity under free-living conditions in female adults.
abstract: BACKGROUND
  The minute-by-minute stepping rate (MMSR) is a unique index of the walking speed. The MMSR under free-living conditions remains unclear.
  
  
  OBJECTIVE
  The purpose of the present investigation was to clarify the physical activity (PA) levels based on MMSR under free-living conditions.
  
  
  METHODS
  A total of 85 female volunteers, age from 21 to 91 year, wore a pedometer with a uni-axial accelerometer (Lifecorder, Kenz, Japan) for 7 days consecutively in order to determine the number of steps, the intensity of PA (light intensity PA; LPA, moderate intensity PA; MPA, and vigorous intensity PA; VPA), and the MMSR. Thereafter, the daily time spent in PA at <100, 100 to 129, and 130 steps min(-1) (min day(-1)) was calculated. All experiments were conducted in March 2007.
  
  
  RESULTS
  The number of steps, the time spent in LPA, MPA, VPA, PA at <100, 100 to 129, and 130 steps min(-1) were 9275±3453 steps day(-1), 71±25 min day(-1), 34±22 min day(-1), 4±6 min day(-1), 295±88 min day(-1), 16±12 min day(-1), and 4±6 min day(-1). The time spent in PA at <100 steps min(-1) positively associated with age (p<0.05). The time spent in PA at 100 to 129 steps min(-1) negatively associated with age (p<0.01).
  
  
  CONCLUSIONS
  The time spent in PA at <130 of steps min(-1) MMSR differs across different age-groups under free-living conditions in female adults. The clinical significance with regards to the age-associated changes in MMSR remains unclear.
authors.affiliation: School of Health and Sport Science, Juntendo University, Chiba, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Ayabe
authors.forename: Junichiro
authors.initials: J
authors.lastname: Aoki
authors.forename: Hideaki
authors.initials: H
authors.lastname: Kumahara
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Tanaka
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D005260:Female; D006801:Humans; D007702:Kinetocardiography; D008875:Middle Aged; D016138:Walking / Q000502:physiology*; D055815:Young Adult