Objective: To investigate the associations of moderate to vigorous intensity physical activity (MVPA) and screen time (ST) with emotional and behavioral problems in children and to provide evidence for related intervention measures. Methods: In March 2017, a total of 4 922 children aged 6-12 years from 5 primary schools in Guangzhou were enrolled using stratified random cluster sampling method. Questionnaires were used to assess children s socio demographic information, MVPA, ST and emotional and behavioral problems. The associations of MVPA and ST with behavioral problems were explored by using generalized linear mixed models. Results: Students with MVPA≥60 min per day accounted for 37.5%, and with ST≤2 h per day accounted for 87.7%. Children who were physically active showed lower scores for total difficulties, hyperactivity, and peer problems and higher score for prosocial than inactive peers( t =2.80, 2.47, 2.56, -1.97, all P <0.05). Also, children who spent less than 2 h ST per day reported lower scores for total difficulties, emotional symptoms, conduct problems, hyperactivity, and peer problems and higher score for prosocial compared to those with high ST( t =3.18, 3.35, 3.70, 3.80, -3.21, 4.97, all P <0.05). Children who met neither MVPA nor ST recommendations had significantly increased risks of total difficulties( OR=1.73, 95%CI =1.12-2.68), conduct problems( OR=1.45, 95%CI =1.02-2.05), peer problems( OR=1.93, 95%CI =1.11-3.36), and prosocial ( OR=1.55, 95%CI =1.08-2.23) than those who met both. Conclusion MVPA and ST are independently related to children s emotional and behavioral problems, and the risks of emotional and behavioral problems increased in children with insufficient MVPA and longer ST.

Objective: To investigate the prevalence of metabolic syndrome (MS) and to explore the relationship of MS with screen time (ST) among children aged 6-13 years in Guangzhou, China. Methods: A total of 4 523 children aged 6-13 from 5 primary schools in Guangzhou were selected using stratified random cluster sampling method. Questionnaire was used to assess children’s basic demographic characteristics and ST. Children’s height, weight, waist circumference and blood pressure were measured objectively, and their blood glucose, triglyceride and high-density lipoprotein-cholesterol were tested. -Chi-square test was performed to compare the prevalence of MS in children among different ST levels. Logistic regression model was used to explore the association between ST and MS. Results: The prevalence of MS in children was 2.4%, and that among boys (3.0%) was higher than in girls (1.7%, P=0.01). children were classified into three groups according to duration of ST: low ST (less than 1 h), moderate ST (1-2 h), high ST (higher than 2 h, 9.0% of total participants). Prevalence of central obesity, triacylglycerol and MS in high ST group was significantly higher than children with low ST(P<0.05). Children with high level of ST showed higher risks of central obesity (OR=1.43, 95%CI=1.04-1.96) and MS (OR=1.94, 95%CI=1.11-3.40) compared with low-level ST group. Conclusion Higher level of screen time associates with an increased risk of MS in children, which suggest the importance of effective early intervention.