Assessment of Daily Physical Activity by a Pedometer

In Healthy Japan 2010, ten thousands walking steps per day is recommended as an individual target of the physical activity(PA). However, this recommendation has little evidence in terms of total energy expenditure (TEE) per day. In this study, we compared between the daily TEE using the newly developed quantitative PA questionnaire (NPAQ) and daily steps using a pedometer in order to assess whether daily steps(DWS) could be a reasonable target as daily PA. Subjects included 180 middle-aged people aged 58.0 ± 7.5yr. TEE was computed from NPAQ as the sum of the energy expended in sleep, home activities, light, moderate, hard and very hard activities using the 7day recall type energy expenditure calculating algorism. Daily TEE was calculated on weekdays and at weekends separately. DWS were obtained using an electric pedometer. Participants wore the pedometer for 7 consecutive days and answered NPAQ on the 8th day. Mean TEE of week days and week ends were 40.7 ± 4.8 and 39.3 ± 5.2 (METs-hr) respectively. Mean DWS of week days and week ends were 9,383 ± 3,682 and 8,293 ± 6,057 respectively. Spearman correlation coefficients between TEE and DWS were 0.50 in men and 0.07 in women on the weekdays and 0.66 and 0.22 at the weekends respectively. High correlation coefficients between the total steps and the total duration (min-week−1) of each NPAQ activities were 0.27 (walking quickly in women) 0.37 (working with standing in men) and 0.39 (walking quickly in men). DWS have an advantage of setting a standard for TEE with ease. However, DWS does not include PA such as swimming, bicycling, and low intensity home activities. Though the greater part of TEE is estimated by DWS in men, PA assessment by DWS in women was underestimated when most of daily PA consisted of home activities.