Background: It is reported that there is an increase in bone mass throughout childhood with a marked acceleration in accumulation at puberty, and physical activity in childhood is valid for bone acquisition. In the present study, we investigated the relationship between various lifestyles and acquired bone mineral content in elementary school children in Japan.
Methods: The subjects were 237 children (boys and girls, 10-12 years old) in 4 elementary schools in Japan. The questionnaire survey and the measurement of bone mineral content were conducted in September and October in 2013. The contents of the questionnaire were bedtime, waking time, hours of sleep, physical activity, and experience of dieting. Whole body bone mineral content (BMC), fat mass, and lean body mass were measured using a single dual-energy X-ray absorptiometry scanner. This study received institutional review board approval, and all subjects provided informed consent.
Results: In boys, BMC was positively associated with experience of dieting (ρ=0.329, p < 0.001). Percent of fat mass was positively associated with playing outside (ρ=-0.350, p < 0.001), physical exercise (ρ=-0.364, p < 0.001), and positively associated with experience of dieting (ρ=0.513, p < 0.001). In girls, BMC was negatively associated with sleeping hour (ρ=-0.266, p=0.003), and positively associated with experience of dieting (ρ=0.250, p=0.005). Percent of fat was negatively associated with physical activity (ρ=-0.260, p=0.004), and positively associated with experience of dieting (ρ=0.275, p=0.002).
Conclusion: In the present study, related life styles were different between BMC and percent body fat.
Disclosure: The authors declared no competing interests. Grant-in-Aid for Scientific Research (B) No. 24370101.