日常生活での相対的中等強度の身体活動が体重，体脂肪率，最大下有酸素性作業能力と脚力の変化に及ぼす影響

Abstract

Purpose: The present study was conducted to clarify the effect of physical activity (PA) at relatively moderate intensity (RMI) during daily life on body weight (BW), percentage body fat (%Fat), submaximal aerobic capacity, and leg extension power (LEP). Methods: Sixty women (aged 57.2±7.6 yr), who were participating in a health exercise training course, were studied. To determine the duration of PA at RMI in each subject, data derived from the double product break point (DPBP) and use of a pedometer with a uniaxial accelerometer (LC; Lifecorder, Kenz) were used. Since the LC can automatically determine the exercise intensity (on a 0-9 scale) during PA with its original algorithm, we defined the exercise intensity corresponding to DPBP as RMI, that above this DPBP equivalent as relatively vigorous intensity, and that below this DPBP as relatively light intensity. The exercise training course was carried out once a week for twelve weeks. The program consisted of lectures on exercise and nutrition, and exercise training. Statistical analysis was carried out to examine the relationship between LC data and parameters of interest, such as changes in BW, %Fat, metabolic equivalents at DPBP (METs@DPBP), and LEP per lean body mass (LEP/LBM). Results: Stepwise regression analysis showed that the changes in BW and %Fat were significantly affected by the values of BW and %Fat at the beginning of the course, and also total PA energy expenditure (p<0.001, respectively). The degree of METs@DPBP change was significantly affected by the total number of steps per day and the duration of PA at RMI (p<0.001). The degree of change in LEP/LBM was significantly affected by its initial value (p<0.001). Conclusion: The present results demonstrate that PA volume, but not exercise intensity, has an impact on BW and %Fat. In addition, it is suggested that the duration of PA at a relatively moderate intensity is crucial for improvement of METs@DPBP.