Evidence for an independent role of increased physical activity in the primary prevention of
coronary heart disease has grown in recent years. The authors apply the techniques of meta-
analysis to data extracted from the published literature by Powell et al.(Ann Rev Public
Health 1987; 8: 253–87), as well as more recent studies addressing this relation, in order to
make formal quantitative statements and to explore features of study design that influence
the observed relation between physical activity and coronary heart disease risk. They find …

We would like to commend Dr. Berlin and Dr. Colditz (1) on their meta-analysis of data
originally reported by Powell et al.(2) concerning the relation between physical activity and
coronary heart disease (CHD). We are pleased that the meta-analysis provides additional
confirmation of the original paper. We would also like your readers to be aware of the close
similarities between the conclusions of Berlin and Colditz and the conclusions previously
published in other papers that used the same data and much simpler analytical methods …