title: [How many days of pedometer monitoring predict weekly physical activity in Japanese adults?].
abstract: OBJECTIVE
  The study purpose was to establish the number (and type) of days needed to estimate mean pedometer-determined steps/day among Japanese adults.
  
  
  METHODS
  DuringJune and August of 2008, seven days of data were collected from 223 participants in S Center between 20 and 64 years old and living in Shizuoka Prefecture (63 males, age = 50.3 +/- 10.4 years, BMI=25.8+/-3.7kg/m2; 160 females, age=49.0+/-10.6 years, BMI=23.5+/-3.8kg/m2)). Mean steps/day were computed for all 7 days, each single day, and combinations of days. Analyses used in this study were repeated measures analysis of variance, intra-class correlations (ICC) and regression analyses.
  
  
  RESULTS
  The study participants averaged 8,854+/-3,356 steps/day over the 7-day monitoring frame. There were no gender differences in steps/day for any days of the week or for the weekly average of steps/ day. There was a significant difference (F=3.91, df= 5.21, P<0.001) between days for the total sample, Tuesday and Friday showing significantly more steps than Saturday and Sunday (P< 0.001). ICC analyses found a minimum of 3 days is necessary to achieve a reliability of 0.80. The adjusted R2 of 35 models for 3 days were all 0.80 or more.
  
  
  CONCLUSIONS
  This study suggests any 3 days at random can provide a sufficient estimate tor predict weekly physical activity among Japanese adults. Further studies on sample size and survey period are now required.
authors.affiliation: Tokai University.
authors.forename: Akio
authors.initials: A
authors.lastname: Kubota
authors.forename: Junko
authors.initials: J
authors.lastname: Nagata
authors.forename: Masumi
authors.initials: M
authors.lastname: Sugiyama
authors.forename: Kimie
authors.initials: K
authors.lastname: Ishiduka
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Unno
mesh_terms: D000328:Adult; D044466:Asian People; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D009043:Motor Activity / Q000502:physiology*; D016138:Walking