Kessler1 has drawn attention to the importance of attaining clarity with regard to the objectives of physical fitness. In fact, few basic medical terms are equally vaguely defined and similarly loosely used. Of the many aspects of fitness, we intend to deal in this paper with only one: that of physical efficiency. The fundamental importance of this problem has not yet been fully recognized by the medical profession. It is insufficiently realized that the standard of physical efficiency dictates largely the rate of industrial and agricultural production, that it is one of the primary determinants of military preparedness, that it has a bearing on the health of the nation and that it influences the rate of progress of education.
One of the main reasons for the difficulty of giving a clear definition of the term physical efficiency is lack of quantitative information on the subject. In his "Theory of