Conclusions Multicomponent interventions which also include the use of st and ing desks may be an effective method for reducing  children 's sedentary time  in a school-based intervention .
Introduction Prolonged , uninterrupted periods of sedentary time may be associated with increased risk of Type II diabetes , cardiovascular disease and all-cause mortality even if the minimum recommended levels of daily physical activity are achieved .
It is reported that children spend approximately 80 % of their day engaged in sedentary behaviours .
Since children spend a large portion of their waking time at school , school-based interventions targeting excessive or interrupted periods of sedentary time have been investigated in a number of studies .
However , results of the effectiveness of studies to- date have been inconsistent .
Aim To conduct a systematic review to evaluate the effectiveness of school-based interventions design ed to reduce sedentary behaviour on objective ly measured sedentary time in children .
What helps children to move more at school recess and lunchtime? Mid-intervention results from Transform-Us! cluster-randomised controlled trial
Background To investigate the interpersonal and physical environment mediators of the Transform-Us ! mid-intervention effects on  physical activity ( PA )  during recess and lunchtime . Methods Transform-Us ! is a clustered r and omised school-based intervention with four groups : sedentary behaviour intervention ( SB-I ) , PA intervention ( PA-I ) , combined PA+SB-I and control group .  All children in grade 3 from 20 participating primary schools in Melbourne , Australia were eligible to complete annual evaluation assessment s. The outcomes were the proportion of time spent in moderate-to-vigorous PA ( MVPA ) and light PA ( LPA )  during recess and lunchtime assessed by accelerometers . Potential mediators included : perceived social support from teachers ; perceived availability of line markings ; perceived accessibility of sports equipment ; and perceived school play environment . Generalised linear models were used and mediation effects were estimated by product-of-coefficients ( a·b ) approach . Results 268 children ( 8.2 years , 57 % girls at baseline ) provided complete data at both time points . A significant intervention effect on MVPA during recess in the SB-I and PA-I groups compared with the control group ( proportional difference in MVPA time ; 38 % ( 95 % CI 21 % to 57 % ) and 40 % ( 95 % CI 20 % to 62 % ) , respectively ) was found . The perceived school play environment was significantly positively associated with MVPA at recess among girls . An increase in perceived social support from teachers suppressed  the PA+SB-I effect on light PA  during recess ( a·b= −0.03 , 95 % CI −0.06 to −0.00 ) . No significant mediating effects  on PA during recess and lunchtime were observed . Conclusions A positive perception of the school play environment was associated with higher MVPA during recess among girls . Future studies should conduct mediation analyses to explore underlying mechanisms of PA interventions
Conclusions Multicomponent interventions which also include the use of st and ing desks may be an effective method for reducing  children 's sedentary time  in a school-based intervention .
Introduction Prolonged , uninterrupted periods of sedentary time may be associated with increased risk of Type II diabetes , cardiovascular disease and all-cause mortality even if the minimum recommended levels of daily physical activity are achieved .
It is reported that children spend approximately 80 % of their day engaged in sedentary behaviours .
Since children spend a large portion of their waking time at school , school-based interventions targeting excessive or interrupted periods of sedentary time have been investigated in a number of studies .
However , results of the effectiveness of studies to- date have been inconsistent .
Aim To conduct a systematic review to evaluate the effectiveness of school-based interventions design ed to reduce sedentary behaviour on objective ly measured sedentary time in children .