Determinants and prediction methods of total energy expenditure – efforts at National Institute of Health and Nutrition in Japan – / 体力科学

The National Institute of Health and Nutrition, as a part of the National Institutes of Biomedical Innovation, Health and Nutrition at present, has put emphasis on energy metabolism research since its establishment in 1920. After 2000, the National Institute of Health and Nutrition introduced doubly labeled water method and human calorimeters and has also contributed to the establishment of energy requirements in the Dietary Reference Intakes for Japanese. Inter-individual differences in physical activity level are large and difficult to accurately evaluate. Therefore, various studies have been conducted using not only subjective methods such as questionnaire but also objective methods such as accelerometry. Moreover, determinants of total energy expenditure and physical activity have been investigated, including comparison of physical activity level between normal-weight and obese adults. New evidences on contribution of brown adipose tissue activity and diseases on energy metabolism have been obtained. In the near future, research to elucidate the mechanism of energy balance, more accurate and variety of assessment of physical activity, and examination from the viewpoints of chrono-nutrition and chrono-exercise are expected.

Effects of a lifestyle intervention using an activity monitor with game functions on physical activity-A randomized crossover study- / 体力科学

This study aimed at clarifying the effects of a lifestyle intervention using an activity monitor with game functions on daily physical activity. A 12-week randomized crossover study was conducted in 23 healthy volunteers (31 ± 11 yrs). The subjects were randomly assigned to Group A (a 6-week game intervention and then a 6-week normal intervention) and Group B (a 6-week normal intervention and then a 6-week game intervention). In the game intervention period (G), the subjects wore two different activity monitors, namely a normal activity monitor (Lifecorder EX) and an activity monitor with game functions (Yuuhokei). On the other hand, in the normal intervention period (N), the subjects wore only a normal activity monitor. Daily steps were significantly higher in the G than in the N (G: 10417 ± 2358 vs. N: 8744 ± 2180 steps/day, P < 0.001). Amount of physical activity (<i>i.e.</i>, daily total METs · hour = Ex/day) at the intensity of 3 METs or more was significantly higher in the G than in the N (G: 3.1 ± 0.9 vs. N: 2.4 ± 0.8 Ex/day, P < 0.001). Our results indicate that the lifestyle intervention using an activity monitor with game functions would more effectively increase daily physical activity such as steps and physical activity amount, than a normal intervention using an activity monitor. These findings therefore have important implications for reaching more easily the goals (<i>i.e.</i>, 23 Ex/week or 10,000 steps/day) and the use of an activity monitor with game functions in the field of exercise or physical activity instructions.

QUANTIFYING TIME SPENT IN MODERATE TO VIGOROUS INTENSITY PHYSICAL ACTIVITY VIA STEPPING RATE / 体力科学

The purpose of the present investigation was to examine the usefulness of the stepping rate for assessing the time spent in moderate to vigorous intensity physical activity (MVPA). In the present investigation, 11 young men wore two pedometers (LIFECORDER EX ; KZ, Walking Style ; WS) during controlled walking and jogging, as well as during free-living conditions for 3 days. In addition to the number of steps, the KZ determined the time spent in physical activity based on the intensity of the physical activity (light intensity physical activity (LPA); below 3 METs, and MVPA ; above 3 METs), and the stepping rate (≧60, ≧80, or ≧100 steps·min^-1). In contrast, the WS was defined as the physical activity for a stepping rate of 60 steps·min^-1 or more, continuously for longer than 10 min as the time spent in physical activity. Regarding the results, under continuous walking/jogging, the KZ-assessed LPA and MVPA well reflected the intensity of the physical activity. On the other hand, the WS accumulated the time spent in physical activity for longer than 90% of the actual exercise duration, regardless of the walking speed. Furthermore, the stepping rate corresponding to 3 METs was 102 steps·min^-1. Under free-living conditions, however, the KZ-detected MVPA differed significantly in comparison to the time of the physical activity as determined by the other algorithms, except for the time spent in a stepping rate of 80 or higher steps·min^-1. In conclusion, these results indicate that 100 steps·min^-1 is a useful stepping rate for the assessment of MVPA. However, under free living conditions, the stepping rate should be determined at a higher frequency than a one minute interval length in order to improve the accuracy of the MVPA assessment.