Purpose: The purpose of this study was to investigate the free-living physical activities using accelerometer in a general Japanese population. Methods: The 2066 participants attached accelerometer for more than 7 days. We analyzed the data from 767 men and 1111 women ≧20 yr (mean age = 64±12 yr) whose physical activity data were available. The mean walking steps, metabolic equivalent tasks (METs)・hours express as Exercise (Ex), and the energy expenditure of free-living physical activity were calculated. Results: The mean daily walking steps and energy expenditure were 6499.4±3476.5 steps and 2186.7±347.2 kcal in men and 6061.1±2936.7 steps and 1770.8±292.4 kcal in women (p<0.01, respectively). The daily Ex for walking in men (201.7±121.2 Ex) was significantly higher than that in women (115.5±69.4 Ex, p<0.01). On the other hand, the daily Ex for other physical activity in men (433.8±137.0 Ex) was significantly lower than that in women (461.2±127.4 Ex, p<0.01). All measurements were significantly decreased with aging, especially in 70 and 80 age groups (p<0.05). Conclusions: Free-living physical activities significantly differ among sex or age groups. Additional studies using accelerometer are needed to demonstrate the relationship between physical activities and several lifestyle-related diseases in a general Japanese population
