ObjectiveTo analyze the relationship between 24‐h movement behaviors and adolescents' physical fitness, with sex difference and age disparity explored specifically.MethodsA total of 135 852 Chinese adolescents aged 13–22 years were included in this cross‐sectional study. Self‐reported 24‐h movement behavioral times, including moderate to vigorous physical activity (MVPA), recreational screen, and sleep, were identified as meeting guidelines based on Canadian recommendations. Physical fitness indicator (PFI) was calculated through sex‐ and age‐specific z scores of body mass index, forced vital capacity, 50 m dash, sit‐and‐reach, standing long jump, body muscle strength, and endurance running, and then classified as: low level (<20th), middle level (20th–80th), and high level (>80th). Mixed effect logistic regression was applied to analyze the association, and interaction terms were constructed to prove the sex and age disparities.ResultsOnly 12.4% of adolescents aged 13–22 years met all three recommendations. The number of meeting guidelines exhibited a typical dose–response relationship with high level PFI (OR = 1.22 [95% CI: 1.19–1.25]), and in detail, meeting MVPA + recreational screen (OR = 2.29 [95% CI: 2.09–2.51]) or MVPA‐only (OR = 2.16 [95% CI: 1.93–2.41]) guidelines were better associated with high‐level PFI. Besides, meeting MVPA‐only guideline was proved with stronger association with high‐level PFI for boys (p‐interaction = 0.005). The dose–response relationship in boys of the number of guidelines met with PFI was stronger in 19‐ to 22‐year‐olds (p‐interaction <0.001) and 16‐ to 18‐year‐olds (p‐interaction = 0.001) than that in 13‐ to 15‐year‐olds.ConclusionThe prevalence of meeting 24‐h movement behaviors guidelines among Chinese adolescents aged 13–22 years was relatively low. It was associated with adolescents' physical fitness, with meeting MVPA + recreational screen or MVPA‐only guidelines bringing greater benefits, and sex difference and age disparity existing.

Background: Additional metabolic indicators ought to be combined as outcome variables when exploring the impact of breastfeeding on obesity risk. Given the role of a healthy lifestyle in reducing obesity, we aimed to assess the effect of breastfeeding duration on different obesity phenotypes according to metabolic status in children and adolescents, and to explore the offsetting effect of healthy lifestyle factors on the associations between breastfeeding duration and obesity phenotypes. Methods: A total of 8208 eligible children and adolescents aged 7–18 years were recruited from a Chinese national cross-sectional study conducted in 2013. Anthropometric indicators were measured in the survey sites, metabolic indicators were tested from fasting blood samples, and breastfeeding duration and sociodemographic factors were collected by questionnaires. According to anthropometric and metabolic indicators, obesity phenotypes were divided into metabolic healthy normal weight (MHNW), metabolic unhealthy normal weight (MUNW), metabolic healthy obesity (MHO), and metabolic unhealthy obesity (MUO). Four common obesity risk factors (dietary consumption, physical activity, screen time, and sleep duration) were used to construct a healthy lifestyle score. Scores on the lifestyle index ranged from 0 to 4 and were further divided into unfavorable lifestyles (zero or one healthy lifestyle factor), intermediate lifestyles (two healthy lifestyle factors), and favorable lifestyle (three or four healthy lifestyle factors). Multinomial logistic regression was used to estimate the odds ratio (OR) and 95% confidence interval (95% CI) for the associations between breastfeeding duration and obesity phenotypes. Furthermore, the interaction terms of breastfeeding duration and each healthy lifestyle category were tested to explore the offsetting effect of lifestyle factors. Results: The prevalence of obesity among Chinese children and adolescents aged 7–18 years was 11.0%. Among the children and adolescents with obesity, the prevalence of MHO and MUO was 41.0% and 59.0%, respectively. Compared to the children and adolescents who were breastfed for 6–11 months, prolonged breastfeeding (≥12 months) increased the risks of MUNW (OR = 1.35, 95% CI: 1.19–1.52), MHO (OR = 1.61, 95% CI: 1.27–2.05), and MUO (OR = 1.46, 95% CI: 1.20–1.76). When stratified by healthy lifestyle category, there was a typical dose–response relationship between duration of breastfeeding over 12 months and MUNW, MHO, and MUO, with an increased risk of a favorable lifestyle moved to an unfavorable lifestyle. Conclusions: Prolonged breastfeeding (≥12 months) may be associated with increased risks of MUNW, MHO, and MUO, and the benefits of breastfeeding among children and adolescents may begin to wane around the age of 12 months. The increased risks may be largely offset by a favorable lifestyle.

No abstract