Physical activity and coronary heart disease

Fifty years of research confirms inverse relationship

Fifty years ago the first empirical investigation of what was subsequently termed the exercise hypothesis—physical activity reduces the occurrence of coronary heart disease—was undertaken by Morris et al.1 Using data from two cohorts of British workers, they reported lower rates of coronary heart disease in bus conductors than in less occupationally active bus drivers, and in postmen relative to deskbound telephonists and other office based employees. Although this research was pioneering, it was not without its shortcomings. Early statistical methods were limited in their capacity to explore the issue of confounding—for example, it was possible that higher levels of overweight, high blood pressure, stress, or pre-existing ischaemia in the less active groups, rather than their sedentary behaviour, placed them at increased risk of coronary heart disease. Further, the study focused exclusively on work activity. Morris et al, and subsequently Paffenbarger et al, went on to address these issues, showing physical activity in leisure time to be cardioprotective, an effect that held after a range …