Time to challenge public health guidelines on physical activity.

There is striking evidence in support of physical activity (PA) as a very strong factor in health promotion and disease prevention. Since the mid-1990s, public health guidelines on PA have established PA recommendations to promote health and prevent several non-communicable diseases (NCDs). However, it is not clear that there is universal agreement on the validity of all aspects of these recommendations. Indeed, a growing body of evidence has accumulated over the last 20 years showing that less than 150 min/week of moderate PA, i.e. the minimum PA level currently recommended, promotes health and prevents NCDs. Moreover, when determining whether someone achieves the minimum PA recommendations, the quantities of PA undertaken are added together regardless of what domain of PA they represent, i.e. leisure-time, occupational, transport or housework. However, while convincing evidence exists to show that leisure-time and transport PA are important factors for promoting health, the evidence for occupational PA and housework is mixed. Therefore, the purpose of this article is to discuss two major issues relating to public health guidelines on PA for adults and older adults: the minimum volumes of PA required and the importance of PA domains in health promotion. A proposal on how to tackle these issues and ultimately strengthen PA recommendations is also presented.