Time trends for step-determined physical activity among Japanese adults

The study's purpose was to describe the most recently reported (2007) step-determined physical activity and trends from 1995 to 2007 among Japanese adults.

Data were extracted from published reports of the Japan Heath and Nutrition Survey, which has been conducted annually by the Ministry of Health, Labour and Welfare of Japan using a nationally representative Japanese adult sample of 6502-9833 participants (≥20 yr) each year. Pedometer data were collected on an individually specified weekday in November each year. Because of the change in age distribution of the sample, steps per day were adjusted by age to examine time trends.

Men took 7321 ± 4588 (mean ± SD) steps per day and women took 6267 ± 3827 steps per day in the Japan Heath and Nutrition Survey 2007. Men took more steps per day than women in all age groups. Steps per day were lower with older age groups among men, whereas among women, the 40- to 49-yr-old age group took the highest steps per day relative to other ages. Time trends displayed a decline of age-adjusted mean steps per day (-529 steps per day among men and -857 steps per day among women) from peak values in 1998-2000 to 2007. Decreases in percent of people classified as active (age-adjusted proportion taking ≥10,000 steps per day = -5.1% among men and -5.0% among women) and increases in percent classified as sedentary (age-adjusted proportion taking <4000 steps per day = +4.8% among men and +8.2% among women) were also observed during the same period.

Japanese steps per day have decreased over time from a peak around 1998-2000. The increase in the percent taking <4000 steps per day was especially noticeable among women.