ABSTRACT
This chapter evaluates the way in which biomedical evidence for the efficacy of physical activity in conferring a range of health benefits and reducing all-cause mortality risk has been interpreted and misinterpreted to set physical activity guideline recommendations around the world. All current guidelines recommend 150 minutes moderate physical activity per week as providing substantial health benefits for adults, with some suggesting this is the minimum level at which health benefits accrue. However, the biomedical evidence shows 60 minutes is sufficient to provide some health benefits. None of the guidelines consider effectiveness evidence nor potential effectiveness, and there is no evidence for the effectiveness of a recommendation of 150 minutes in improving population health. There has been no consideration in drawing up any of the guidelines whether a recommendation at a lower but still sufficient level of efficacy (e.g. 60 minutes) would be a more effective public health intervention. Because only biomedical evidence is considered in drawing up physical activity guidelines neither effectiveness nor comparative effectiveness is considered. It is therefore possible that current guidelines of 150 minutes may result in net harm to population health in comparison to the opportunity cost of recommendations at alternative levels.
