Intensity and amount of habitual physical activity for health: Special considerations in middle-aged and older Japanese adults

抄録

The present review aims to summarize current evidence regarding the intensity and amount of habitual physical activity required to obtain health benefits, in particular among middle-aged and older Japanese adults. In association with current technological advances, it has now become possible to assess the degree of habitual physical activity objectively using small activity monitors, such as pedometers and/or accelerometers. Three metabolic equivalents (METs) is widely accepted to be the appropriate intensity of habitual physical activity, and 30 to 60 minutes of daily physical activity at an intensity above three METs is considered to reduce the risk of lifestyle-related diseases in adults. Although interindividual variability in the appropriate number of steps is not small, these target levels generally correspond to 6,500-11,000 steps per day, and several studies have reported the clinical significance of 7,000-10,000 steps/day with respect to benefits on the immune function, muscle mass and prevention of metabolic syndrome. However, these target levels for the amount and intensity of habitual physical activity may be inadequate to maintain physical fitness, because the intensity of >3 METs is not guaranteed to induce exercise adaptability in all adults. Future research should therefore focus on the relative intensity identified according to the consensus intensity for safety and effectiveness, including the lactate threshold and/or percentage of maximal oxygen uptake under the free-living conditions, as well as fixed intensity exercise, such as that involving three or six METs.