Variation in sexual dimorphism in relation to physical activity.

Abstract

The aim of this study was to examine variations in sexual dimorphism in relation to physical activity. A sample of 542 males and females (20-30 years), born and resident in Cagliari (Sardinia, Italy), was divided into two groups: active and inactive. Twenty-five anthropometric dimensions were taken (weight, lengths, breadths, circumferences, and skinfolds). The circumferences and skinfolds were adjusted for the effects of overall body size (represented by skeletal variables). Body composition parameters--fat-free mass (FFM), fat mass (FM), and arm muscular area (AMA)--were derived from the adjusted values. The D index (Bennett, 1981; Chakraborty and Majumder, 1982) was used to assess the degree of sexual dimorphism. The difference between the D values of active and inactive individuals was analyzed with the technique of Bennett (1981). Principal components analysis (PCA) was performed on groups of homogeneous variables (circumferences and skinfolds) in order to simplify the description of the original anthropometric data. The univariate and multivariate analyses indicate a greater sex difference in the group of individuals who are regularly active. The results agree with theoretical expectations, and suggest greater stability of women to environmental pressures (i.e., physical activity).