摘要：Small physical activity increases may prevent weight gain in most populations. Geneva residents completed validated quantitative physical activity frequency questionnaires from 1997 to 2001. Fifteen minutes per day of moderate or brisk walking, or 30 minutes per day of slow walking, could increase physical activity at the population level; however, if the specific goal is to approach expending 420 kJ/d (100 kcal/d) through walking, the duration should be closer to 60 minutes for slow walking and 30 minutes for moderate or brisk walking. A worldwide obesity epidemic 1, 2 has led to an urgent need to design populationwide weight-control campaigns. A postulate is that small increases in physical activity may prevent weight gain in most populations because an extra 420 kJ/d (100 kcal/d) can compensate for the observed weight gain. 3 However, how much daily walking is needed to reach that goal is unknown. The intensity of a physical activity can be assessed by the energy expenditure it produces in terms of a multiple of an individual’s (sex-age-height-weight-specific) basal metabolic rate, which is the resting energy expenditure rate. 4 The typical basal metabolic rate of a Western adult is 4.2 kJ/min. Walking slowly expends 3.1 times one’s basal metabolic rate. Hence, someone with a basal metabolic rate of 4.2 who walks slowly for 15 minutes expends 195 kJ. We used a unique monitoring system for measuring the total energy expenditure of the adult resident population of Geneva, Switzerland, to simulate the potential effect of campaigns promoting different combinations of duration and intensity of daily walking on the population’s total energy expenditure.
