The award of the Olympic and Paralympic Games to Tokyo in 2020 provides an opportunity for developing a Health and Physical Activity Legacy following this event. This review examines the published evidence that the Olympic Games or Paralympic Games lead to an increase in population levels of physical activity or participation in sport. Specific examples from the Sydney 2000 Olympic Games, the Vancouver Winter Olympics 2010, and preliminary data from the London 2012 Olympic Games failed to demonstrate increases in physical activity or sport participation amongst representative samples of adults or children, assessed using serial population surveys leading up to and subsequent to the event. The Tokyo Olympic and Paralympic Games offers an opportunity to develop partnerships between the health sector, sports promotion sector, the Olympics movement and exercise epidemiology specialists to develop, implement and evaluate a mass media communications campaigns and communitywide interventions to promote physical activity and sport. These programs should start several years before the Games, capitalise on the momentum provided by hosting the event, and can be assessed for their “legacy contribution” in the years following the Games. Standardised evaluation and monitoring surveillance systems are required to assess this potential impact in representative samples of the Japanese population.

History suggests that research in physical fitness and exercise physiology has developed in conjunction with research in occupational health. However, in recent years, the issues of workers’ physical fitness are not treated as a crucial aspect in occupational health studies. Currently in Japan, we face a serious national issue referred to as our aging and declining population society. In this type of society where the relative number of workers is declining, workers’ health should be one of the most important concerns for both employers and the government. There is an increased need in Japan to maintain workers’ health and extend the years leading up to retirement from the workforce; for this reason, research in physical fitness will again play a significant role in occupational health issues. Although people generally understand the importance of regular exercise, finding time for exercise during non-work (leisure) hours is difficult in our time-pressed society. On the other hand, many workers spend large parts of their waking hours in sedentary behavior. A new way to approach this problem may be through the study of astronauts’ health issues. Although this is not a common topic in occupational health, this field may provide clues to solving life-related disease issues because aspects of the microgravity environment can be compared to a physically inactive society. Astronauts must schedule enough time for exercise despite their extremely busy schedules because a decline in physical fitness can quickly become life threatening in their environment. Although the effect may take longer to manifest in ordinary individuals in our society, many epidemiological studies show that a decline in physical fitness is strongly related to increased morbidity and mortality risks. Promoting health within the workplace, as demonstrated by astronauts, will be key to maintaining workers’ optimal health during an increased number of working years.

At present, an accelerometer is the most accurate method for measuring minute-by-minute physical activity intensity under free-living conditions. Activity monitors with acceleration sensors can predict activity intensity due to the relatively strong relationship between acceleration and physical activity intensity. Uni-axial accelerometers were widely used previously, however, recently multi-axial accelerometers have become popular. Most activities in daily life including walking, are within ±2 G (1 G = 9.8 m/s²), and most non-locomotive activities are < tens of mG, while sedentary behavior is < about 20 mG. Therefore, high resolution is necessary for evaluation of lower intensity activities including sedentary behavior. Different relationships between acceleration and physical activity intensity were observed for locomotive and non-locomotive activities. In order to classify locomotive and non-locomotive activities, several types of indices, such as the coefficient of variation of acceleration count, the ratio of vertical to horizontal acceleration, and the ratio of unfiltered to filtered synthetic acceleration, have been proposed. Prediction errors by the Active style Pro (Omron Healthcare) are relatively minor, particularly in lower intensity activities. Because waist-worn accelerometers are unable to detect the additional energy expenditure resulting from some activities such as cycling, uphill/downhill walking, and holding standing posture with extra weight, the characteristics of the device and algorithm must be considered when determining the type of accelerometers to use. We investigated physical activity levels in a Hisayama population by a tri-axial accelerometer (Active style Pro). Physical activity of 3 METs or more gradually decreased according to age, and a significant sex difference was observed in 2 physical activity patterns. Specifically, locomotive activity and sedentary time were significantly higher in males, and non-locomotive activity was higher in females. We have summarized the significance and feasibility of using tri-axial accelerometer in epidemiological studies, and have introduced several ongoing longitudinal studies, including prospective studies. These ongoing epidemiological studies will provide useful information that can contribute to the development of guidelines related to light-, and middle to vigorous-intensity activities, and sedentary behavior based on objective measurement by a tri-axial accelerometer.

An individual’s discretionary time in a given day is finite, and the components (i.e., behaviors) are allocated in an interdependent manner. A novel statistical approach named the “isotemporal substitution (IS) model” that was developed to consider this interdependency has recently gained popularity, and shows various advantages over typical analytic models used in the field of physical activity epidemiology. Despite these advantages, there have been no original or introductory articles on the IS model emerging from Japan. The purposes of this review were to provide an overview of the definition, assumptions, and advantages of the IS model; to summarize the existing literature; and to explore research perspectives in this field. The IS model was designed to estimate the effects of replacing one behavior with another for the same amount of time on outcome measures. This is accomplished by entering a total combined behavior variable (i.e., time spent in sedentary, light, and moderate-vigorous activities, corresponding to the wear time of an accelerometer) along with specific behavioral variables (except for the behavior variable of interest) into the model at the same time. The model then statistically holds the wear time constant, drops the target behavioral variable being reduced, and then enables estimation of the “substitution” effects of reallocating one behavior to another on the outcome measures (e.g., the effects of substituting 60 min/day of sedentary time with moderate-vigorous physical activity). The greatest advantage of the IS model is its better interpretability compared to typical models. This has a potential benefit for establishing public health recommendations and health promotion practices. As of July 29, 2015, a systematic literature search identified 12 relevant articles utilizing the IS model. The content review revealed research needs for studying activity type and posture allocation as exposure variables, clinical populations as subjects, and a longitudinal design. These themes should be future research priorities. We anticipate active use of the IS model and its widespread applications in physical activity epidemiology in Japan.

There is substantial evidence showing that physical activity is associated with better health outcomes and prevents disease development. However, very few intervention studies, especially in Japan, have provided evidence supporting this association. Hence, we launched a research project that was approved by the Japanese Association of Exercise Epidemiology to promote the creation, communication, and utilization of evidence from intervention studies in Japan. The purpose of this research project is to review intervention studies conducted in Japan and to provide adequate information to utilize this evidence in developing strategies for health promotion. This document requests for cooperation for this research project. The project includes intervention studies in the field of exercise epidemiology. The candidate outcomes are lifestyle-related disorders (obesity, hypertension, dyslipidemia, or diabetes), joint diseases (back pain or knee pain), dementia, need for nursing care, sleep disorders, mental health, physical fitness, or physical activity. If there are few intervention studies in a topic, we request researchers to conduct intervention studies to create evidence. If the evidence from intervention studies has been published, we request the authors to submit an article to Research in Exercise Epidemiology to communicate evidence so that it can be used in developing strategies for health promotion. We wish to promote the use of the evidence in developing strategies for health promotion through the website of Japanese Association of Exercise Epidemiology, where series of articles on this topic are publicly released.