Sedentary time among primary school children in south-west Germany: amounts and correlates

BACKGROUND: Sedentary behaviour in children is related to different health consequences such as overweight and cardio-metabolic diseases that can track into adulthood. Previous studies have shown that children spend hours being sedentary, but no data of sedentary time (ST) among German children has been available, yet. Therefore, this study investigated objectively measured amounts and correlates of ST in a sample of German primary school children. METHODS: Children’s physical activity (PA) was objectively assessed for 6 days using a multi-sensor device (Actiheart®; CamNtech, Cambridge, UK). Activity levels were categorized on the basis of energy expenditure (MET) into sedentary, light PA (LPA), and moderate to vigorous PA (MVPA). ST excluding sleeping hours was assessed for 231 children (7.1 ± 0.6 years, male: 45.9%) and analysed for independent groups. Examined factors (parental education, household income, and migration background) were assessed by parental questionnaire. Children’s weight, height and gender were collected in schools. Weight status was calculated on the basis of BMI percentiles. RESULTS: On average, children spent 3.5 ± 1.5 h daily being sedentary, excluding sleeping hours. Significantly higher ST was found in girls (t = −4.6; p < 0.01), in children with migration background (t = −6.9; p < 0.01), at the weekend (t = −2.8; p < 0.01), and among inactive children (t = 6.8; p < 0.01). Additionally, significant correlations with ST in this sample were identified for MVPA (B = −0.99; [−1.09;-0.88], p < 0.01), LPA (B = −0.89; [−0.97;-0.82], p < 0.01), migration background (B = −17.64; [5.24;30.04], p < 0.01), gender (B = −13.48; [−25.94;-1.01], p < 0.05) and household income (B = −4.80; [−9.07; −0.53], p < 0.05). CONCLUSION: Girls, children with migration background, and inactive children were identified as potential risk groups. A higher income was associated with less ST. In general, ST was higher at the weekend. Furthermore, as PA was found to be negatively correlated to ST, these activities may replace each other. Therefore, these findings should be considered in future health interventions. TRIAL REGISTRATION: German Clinical Trials Register (DRKS), DRKS-ID: DRKS00000494 DATE: 25/08/2010.