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Objectives Childhood obesity is a global problem, e.g., due to physical inactivity. External skeletal robustness (Frame-Index) has decreased in German schoolchildren. An association between Frame-Index and physical activity was assumed. Further often body mass index (BMI) is analyzed without reference to bone structure. Therefore, we analyze relationships between Frame-Index, BMI, % body fat, and physical activity. Methods In a cross-sectional study, 691 German children aged 610 years were investigated. BMI, % body fat, Frame-Index, total steps p.w., sports club rate p.w., training time p.d., and TV-time p.d. were determined. Results Total steps (P<0.001), BMI (P<0.001), and % body fat (P=0.024) are positively linked to Frame-Index. Total steps (P<0.001), sports club rate (P=0.001), and training time (P<0.001) are negatively associated with % body fat. Total steps (P=0.017) are negatively linked to BMI. TV-time is positively related to BMI (P<0.001) and % body fat (P<0.001). % Body fat is affected by age (P<0.001), sex (P=0.028), and total steps (P=0.002). BMI is influenced by age (P<0.001), and Frame-Index by sex (P<0.001) and total steps (P=0.029). Principal component analysis indicates an association between BMI and TV-time and Frame-Index and total steps. Conclusions We demonstrate an association between external skeletal robustness and physical activity, which is not captured by in BMI measurements. Children should be physically active in order to maintain skeletal robustness. Am. J. Hum. Biol. 25:404410, 2013.
The pace-of-life syndrome (POLS) hypothesis posits that life-history characteristics, among individual differences in behavior, and physiological traits have coevolved in response to environmental conditions. This hypothesis has generated much research interest because it provides testable predictions concerning the association between the slow-fast life-history continuum and behavioral and physiological traits. Although humans are among the most well-studied species and similar concepts exist in the human literature, the POLS hypothesis has not yet been directly applied to humans. Therefore, we aimed to (i) test predicted relationships between life history, physiology, and behavior in a human population and (ii) better integrate the POLS hypothesis with other similar concepts. Using data of a representative sample of German adolescents, we extracted maturation status for girls (menarche, n = 791) and boys (voice break, n = 486), and a set of health-related risk-taking behaviors and cardiovascular parameters. Maturation status and health-related risk behavior as well as maturation status and cardiovascular physiology covaried in boys and girls. Fast maturing boys and girls had higher blood pressure and expressed more risk-taking behavior than same-aged slow maturing boys and girls, supporting general predictions of the POLS hypothesis. Only some physiological and behavioral traits were positively correlated, suggesting that behavioral and physiological traits might mediate life-history trade-offs differently. Moreover, some aspects of POLS were sex-specific. Overall, the POLS hypothesis shares many similarities with other conceptual frameworks from the human literature and these concepts should be united more thoroughly to stimulate the study of POLS in humans and other animals. Significance statement The pace-of-life syndrome (POLS) hypothesis suggests that life history, behavioral and physiological traits have coevolved in response to environmental conditions. Here, we tested this link in a representative sample of German adolescents, using data from a large health survey (the KIGGs study) containing information on individual age and state of maturity for girls and boys, and a set of health-related risk-taking behaviors and cardiovascular parameters. We found that fast maturing girls and boys had overall higher blood pressure and expressed more risk-taking behavior than same-aged slow maturing girls and boys. Only some behavioral and physiological traits were positively correlated, suggesting that behavioral and physiological traits might mediate life-history trade-offs differently and not necessarily form a syndrome. Our results demonstrate a general link between life history, physiological and behavioral traits in humans, while simultaneously highlighting a more complex and rich set of relationships, since not all relationships followed predictions by the POLS hypothesis.