Trends in Step-determined Physical Activity among Japanese Adults from 1995 to 2016

We tried to clarify the trends in step-determined physical activity (PA) among Japanese adults from 1995 to 2016.

Raw data from the National Health and Nutrition Surveys Japan (NHNS-J) performed between 1995 and 2016 were used, in compliance with the Statistics Act of Japan. NHNS-J was conducted annually by the Japanese government (the Ministry of Health, Labour, and Welfare) using a representative Japanese sample, with the same sampling method every year except in 2012 and 2016. A 1-d pedometer survey was conducted each year as a part of the NHNS-J, on a weekday in November specified by each individual. Because of the difference in age distribution of the samples, age-adjusted mean steps per day were calculated from 1995 to 2016 by sex. The time trends of step-determined PA levels among Japanese adults were described and examined using Joinpoint regression.

The highest age-adjusted mean number of steps for men was 8235 steps per day in 2000, whereas it was 7667 steps per day in 2015. The highest age-adjusted mean numbers of steps for women were 7474 steps per day in 1998 and 6691 steps per day in 2015. The age-adjusted step-determined PA trend showed significantly decreasing trend from 1997 to 2008 in men (annual percentage change, -0.74; P < 0.001) and from 1998 to 2008 (annual percentage change, -1.30; P < 0.001) in women, by Joinpoint regression.

The age-adjusted step-determined PA among Japanese adults between 1995 and 2016 decreased from around 1997 to 1998 until around 2008, but since then, the decreasing trend became unclear both in men and in women. Continuous monitoring of PA trends is essential to assess the effectiveness of policies.