Secular trends in adiposity within the context of changes in BMI across developmental periods among Polish schoolchildren-application of the Slaughter equation.

OBJECTIVES

To estimate secular changes in the body fatness, assessed using the Slaughter equation, in the context of changes in BMI in different developmental periods among Polish schoolchildren studied over nearly 50 years.

METHODS

Data were collected during Polish Anthropological Surveys (1966, 1978, 1988, 2012). The total random sample consisted of 69,746 schoolchildren, aged 7-18. Three periods of development were identified: childhood, early adolescence, and late adolescence. Raw data of BMI were standardized for age classes. Based on the body fat percentage, calculated using Slaughter equation (involving triceps and subscapular skinfold thickness), fat mass (FM; kg), and then fat mass index (FMI = FM/height; kg/m) was assessed to enable comparison between body fatness and BMI. Statistical analyses included two-way ANOVA and post-hoc Tukey's tests.

RESULTS

In boys, in terms of changes per decade, between 1966 and 2012 acceleration in Z-BMI and deceleration in FMI were found, irrespective of developmental period. Regarding girls, deceleration of trend was found in terms of both features, with different intensity, depending on developmental period and year of study. The pattern of changes in FMI depending on developmental period was, to some extent, similar for both sexes.

CONCLUSIONS

Slaughter equation for abovementioned two skinfolds, as a method of body fatness assessment, might be a useful tool for research on boys across different developmental periods, but not on girls. Moreover, it should be used with caution when applied to secular changes in adiposity in both sexes, since the distribution of fat tissue varies across ontogenesis, but also over generations.