Temporal Trends and Projected Daily Step Count from 213,924 Pedometer Data in a Nationally Representative Japanese Population.

PURPOSE This study aimed to describe trends in the daily number of steps taken by the Japanese population from 1995 to 2019, using data from the National Health and Nutrition Survey Japan (NHNS-J), and to project step counts for 2032, the target year of the Health Japan 21 (HJ21) third term, while assessing the feasibility of national physical activity goals. METHODS We analyzed individual, pedometer-based daily step count data from 213,924 participants between 1995 and 2019. Age-adjusted average daily step counts were calculated, then linear regression model was used to project daily step counts for 2032, stratified by age (20-64 yr, 65+ yr) and gender. RESULTS The average number of steps taken by the Japanese population has shown a consistent decline since 2000. The projected daily step counts (95% confidence interval [CI]) for 2032 were as follows: 7499 (6854-8144) steps per day for men 20-64 yr old, 5038 (4091-5985) steps per day for men 65+ yr old, 6073 (5277-6869) steps per day for women 20-64 yr old, and 4620 (3749-5490) steps per day for women 65+ yr old. Significant declines were observed in women 20-64 yr old (beta = -45.8 steps per year, 95% CI = -86.4 to -15.2). The new step count targets set by HJ21 (8000 steps per day for younger adults and 6000 steps per day for older adults) are 6.1% to 26.9% higher than the projected values, particularly for women. CONCLUSIONS Daily step counts in Japan have shown a long-term decline, particularly among women. The projected decline in step counts indicates that the new step targets set by HJ21 may be challenging to achieve, particularly for women. Future public health initiatives should prioritize promoting physical activity in this population.