Secular trends in anthropometric characteristics and their associations with external skeletal robustness among Slovenian young adults’ population

Objectives: To determine secular trends in body height, fat-mass, fat-free mass, and external skeletal robustness in young adults and examine possible relationship between them. Methods: Anthropometric data (body height, body mass; skinfold thickness (SFT) – triceps, abdominal, thigh; circumferences (C) – waist, upper arm, thigh; width – elbow, knee) of young adults aged 20-25 years (N = 5303; males 1985, females 3318) were used from the Slovenian (data)Base of Anthropometric Measurements from 1960 to 2023. Multiple linear regressions were performed. Results: The most significant positive secular trends (p < 0.000) were observed in males for abdominal SFT (B = 0.151, R2 = 0.169) and thigh SFT (B = 0.131, R2 = 0.142). In females, similar trend was observed in waist C (B = 0.151; R2 = 0.169). The most significant negative secular trend (p < 0.001) was observed in muscle area of lower limbs in both sexes (males: B = - 0.427, R2 = 0.000; females: B = - 0.875, R2 = 0.300). Body height and overall body mass were the most important factors influencing the observed decline in external skeletal robustness assessed with frame index according to elbow and knee width according to multiple linear regression. Conclusion: Over the last 60 years, a positive secular trend was observed in body height and body fat, while a negative trend was noted in muscle mass. Increases in body height and overall body mass had the most significant impact on the observed decrease in assessed external skeletal robustness over time.