Physical Development Indices

Physical Development Indices, indicators of physical development, are a special case of anthropometric indices, or ratios of anthropometric measurements. To compare anthropometric data of two individuals or groups, it is necessary to bring these data to one scale. A weight of 70 kg, for example, obviously has different significance for two people if one has a body length of 170 cm and the other 150 cm. Since body length is the main anthropometric dimension, which also shows considerable variability, most anthropometric dimensions are usually brought to one height. Individual diameters (e.g., shoulder width), or chest circumference, or sizes of internal organs can be brought to sitting height or to trunk length. Other dimensions are finally compared, e.g., width and length of the head, anteroposterior and lateral diameters of the chest, etc. As a rule, an index is a percentage ratio of the smaller anthropometric measurement to the larger one; thus, one of the oldest anthropometric indices - the cephalic index - represents the percentage ratio of the greatest width of the head to its length, the chest index (according to Brugsch) - the percentage ratio of chest circumference (at rest) to body length. A number of indices are based on comparing several anthropometric measurements (index of Chulitsky, Pignet, de la Camp, etc.). In medical and pedological literature, those of the indicated ratios that attempt to briefly characterize the physical development of the organism have become most widespread. The number of such physical development indices is quite large, but the principal ones basically come down to accounting for relative weight and relative chest development. Weight is compared: 1) with height to the first degree (Quetelet, Bouchard); 2) with height to the square (Ketle, Gould, Kair, Davenport); 3) with height to the third degree (Buffon, Rohrer, Bardeen); to the latter group also belongs the Livi index, which compares with height the cube root of weight, and the Pirquet index, in which the cube root of the tenfold weight is divided by sitting height. The question of to what degree of height the weight changes proportionally cannot be theoretically resolved; on the basis of extensive anthropometric material, it can be considered empirically proven that this degree is close to the second (Davenport). It should not however be thought that the formula - weight divided by height squared - gives a completely accurate measure of relative weight and for all ages and both sexes (Bunak). Chest circumference is taken into account in an arithmetic relation to half the body length (Erisman) or in a percentage relation to body length (Brugsch); there is a proposal to compare it with the square root of body length. Combined comparison of weight and chest circumference with height is represented in the Pignet index (from height is subtracted the sum of weight and chest circumference). At present, the use of physical development indices has been subjected to critical review in anthropological, and subsequently in medical literature. Despite the significance of data on height, weight, and chest circumference for characterizing the physical development of a collective, proven by numerous studies in the field of child, professional, and military anthropometry, it must be kept in mind that the concept of physical development of the organism and related terms 'robustness', 'sanitary constitution' - is very broad and complex, and anthropometric data in general are only a partial and conditional indicator of them. For characterizing the physical development of an individual - the usual field of application of physical development indices - these data have more limited value, and they must be used with special caution. Norms of physical development based on anthropometric data are not absolute, but vary depending on age, sex, nationality, social status. There is no single 'normal weight', one can only speak of specific norms of weight and chest circumference, i.e., of statistical averages, with which the anthropometric data of an individual or another group should be compared for evaluating physical development. In this evaluation, indices are not an essential aid, because they also depend on sex, age, etc., and do not eliminate the need to have special tables of anthropometric data for each group. Indices do not even achieve their nearest goal - to eliminate height, i.e., by reducing data on weight and chest circumference to one height to make them comparable at least within the limits of a given age, sex, national, and social group. Works by Michelson, Yarkho and others showed that even within a group homogeneous in the indicated characteristics, index values change depending on height. Dependence of indices on height (according to Michelson). Height Index Index Index Ketle Popera Gould 165 ..... 0.36 1.41 0.226 170 ..... 0.37 1.36 0.225 175 ..... 0.38 1.32 0.224 180 ..... 0.39 1.27 0.223 185 ..... 0.40 1.23 0.221 185 ..... 0.41 1.19 0.219 Thus, the main task of indices - to give by a simple formula a brief numerical characterization of physical development of an individual on the basis of his weight and chest circumference regardless of his height - cannot be considered resolved. The apparent simplicity of indices, which served as the main basis for their widespread use, which this method enjoyed for quite a long time, upon more careful critical consideration proves deceptive, which explains the justified criticism that the use of indices has provoked in the selection of children, especially those in need of public nutrition (e.g., during the hunger blockade in Germany, where the Rohrer index was particularly widely applied). The increasingly used in anthropometric studies variation statistics provides more perfect methods for quantitative accounting of the connection between anthropometric characteristics and bringing their values to one height. In evaluating physical development, at present the use of regression tables comes to the fore, in which specific average weights and chest circumferences are given for a given height and for a given more or less homogeneous in composition group of subjects. Complex physical development indices, such as the Pignet or Bornhardt indices, besides the listed shortcomings common to all indices, also have that one that the significance of each of the components entering into them is blurred. Thus, a favorable value of the Pignet index can result from either a large weight of the subject or a large chest circumference, while the biological significance of each of these traits is obviously different. If to this is added that the indices proposed by different authors for evaluating physical development and usually operating with the same data on height, weight, and chest circumference are very numerous, diverse, and often contradictory, then the conclusion that the necessity of such formulas is not so great and their significance is rather limited should be considered fully justified. (See also Bardin-Rohrer index, Bornhardt index, Brugsch index, Gould-Kaup index, etc.).