The scientific and social construction of post-world war II US public health guidelines for physical activity: 1948-1996

摘要

Public health guidelines for (leisure time) physical activity evolved in the United States from scientific research which began in Britain and spread to North America during the second half of the 20th Century. This dissertation examines the guidelines' scientific and social construction. Research questions centre upon what has become known as the 'threshold-intensity vs volume-energy expenditure debate': Is a minimum intensity of physical activity necessary to achieve significant beneficial health outcomes? Or can that effective 'dose' be achieved by accumulating a sufficient total volume of expenditure (kcals) -- regardless of its intensity? The research questions are: 1. Why were public health guidelines switched from a focus upon vigorous intensity to moderate intensity, and was the science base sufficiently sound and uncontested to justify that switch on scientific (and social scientific) grounds? 2. Why were the guidelines so focused on cardiovascular disease (CVD) to the relative exclusion of other health outcomes? 3. Did a small, influential group of investigators play a disproportionate (anomalous) role in shaping the 1996 US Surgeon General's Report on Physical Activity and Health? Conclusions: The US Surgeon General's Report switched public health focus from vigorous to moderate intensity activities on a proclaimed 'emerging consensus' of scientific evidence. However, the science base remained complex and contested. This 'consensus' was, in large measure, socially constructed by a small group of investigators who had gained influence within the American Heart Association, the Centers for Disease Control and Prevention, the National Heart, Lung and Blood Institute, and then the very taskforce selected to write the Report. This dissertation explores a new and relevant area of 'Regulatory Science' given current interest in sedentary lifestyles and illness, not least cardiovascular disease and obesity. Anomalies in scientific interpretation and policy making arose not from financial considerations, but primarily from motives of altruism and professional status.