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 .
Examination of mid-intervention mediating effects on objectively assessed sedentary time among children in the Transform-Us! cluster-randomized controlled trial
Background The optimal targets and strategies for effectively reducing sedentary behavior among young people are unknown . Intervention research that explores changes in mediated effects as well as in outcome behaviors is needed to help inform more effective interventions . Therefore , the purpose of this study was to examine the mid-intervention mediating effects on children ’s objective ly assessed classroom and total weekday sedentary time in the Transform-Us ! intervention . Methods The results are based on 293 children , aged 7- to 9-years-old at baseline , from 20 schools in Melbourne , Australia . Each school was r and omly allocated to one of four groups , which targeted reducing sedentary time in the school and family setting s ( SB ; n = 74 ) , increasing or maintaining moderate- to vigorous-intensity physical activity in the school and family setting s ( PA ; n = 75 ) , combined SB and PA ( SB + PA ; n = 80 ) , or the current practice control ( C ; n = 64 ) . Baseline and mid-intervention data ( 5–9 months ) were collected in 2010 and analyzed in 2012 . Classroom and total weekday sedentary time was objective ly assessed using ActiGraph accelerometers . The hypothesized mediators including , child enjoyment , parent and teacher outcome expectancies , and child perceived access to st and ing opportunities in the classroom environment , were assessed by question naire . Results The SB + PA group spent 13.3 min/day less in weekday sedentary time at mid-intervention compared to the control group . At mid-intervention , children in the SB group had higher enjoyment of st and ing in class ( 0.9 units ; 5-unit scale ) and all intervention groups had more positive perceptions of access to st and ing opportunities in the classroom environment ( 0.3 - 0.4 units ; 3-unit scale ) , compared to the control group . However , none of the hypothesized mediator variables had an effect on sedentary time ; thus , no mediating effects were observed . Conclusions While beneficial intervention effects were observed on some hypothesized mediating variables and total weekday sedentary time at mid-intervention , no significant mediating effects were found . Given the dearth of existing information , future intervention research is needed that explores mediated effects . More work is also needed on the development of reliable mediator measures that are sensitive to change overtime . Trial registration ACTRN12609000715279IS RCT
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 .