Hegarty (236) conducted a systematic review of SB interventions based within the school environment. The review identified 11 papers reporting eight controlled and
102
three non-controlled trials. Studies were limited to the UK, Australia, New Zealand and Belgium, with children of varied socio-economic position, samples ranging from 26 – 2221 children, ages from 7-12 years and interventions of between 4 weeks and 18 months duration. Half of the studies included multi-component interventions, where reducing sedentary time was part of a wider lifestyle-based intervention. The remaining four interventions were single-component, designed to reduce sedentary time only. The multi-component interventions also involved parents assisting their child with intervention activities at home.
The only intervention design that consistently demonstrated a reduction in sedentary time was in those using standing desks within the classroom. Although these studies (n=3) included small samples (Intervention class, n ≤24), had no theoretical underpinning, were single-component interventions and were of short duration (≤10 weeks), they all demonstrated reductions in classroom sitting time of approximately 20-60 min during daily class time (and in total day sitting time in some cases) within intervention groups (91,237,238). The authors concluded that ‘standing desk interventions may be more effective than multi-component school-based interventions in reducing sedentary time.’ Furthermore, it was quite clear that implementing environmental restructuring in this way resulted in very high intervention exposure time compared to other intervention designs. For example, in the Australian trial of the Clemes et al. (91) study, children received a sit-stand desk each and since children remain in one classroom for a full school day at primary school, the potential exposure was approximately 20-30h/week (4-6h/day of classroom time five days a week). The next best exposure time in a non-standing desk intervention was 150 min/week in a multi-component intervention that included teacher-led educational classes, standing lessons, PA breaks and newsletters (190), with other interventions providing around just 1h/day of exposure.
Based on the reviews of Altenburg et al (162) and Hegarty et al (236), standing desks appear to be one of the more promising solutions for reducing total sedentary time in children. Crucially, the school setting is a distinct environment that has many potential benefits and challenges that must be considered before any health intervention is implemented.
103
1.13.1. The school setting for sedentary behaviour intervention
The school setting has been previously identified as an important environment for influencing healthy behaviours (136), partly because children spent most of their waking hours during week days at school (239). A key benefit of this setting is that large numbers of children can be accessed in a single location, which is highly structured with children being closely supervised by teaching staff. Crucially, most schools are likely to include children of diverse demographics (84), with some of higher health risk (i.e. obese, low household income, ethnic minority) who may be more challenging to reach within the community setting. Importantly, in mid-childhood to adolescence (9-15 years), a key stage of maturation occurs where parental influence on behaviour begins to dissipate and the influence of peers becomes stronger (240). Children spend most of their school time, particularly during class time, sedentary (39,81,88). During class time there is evidence that children sit for between 70% and 90% of the time across all subjects, with total sitting time and mean sitting bout lengths increasing as children progress through the school years/grades. (84). Consequently, the classroom would appear to be an important environment to implement strategies for reducing sitting time.
Any health intervention or program that is based within a school setting will need to compete with often crowded school curriculums. Teaching staff and parents will certainly prioritise learning and development-related outcomes on a day-to-day basis. Consequently, any intervention that places demands on academic staff certainly runs the risk of insufficient implementation, compliance and sustainability. This can be further attenuated in teachers who are sceptical of the necessity of a lifestyle-related intervention in an age group that is largely healthy. Insufficient intervention implementation by teachers, mainly due to conflicting curriculum needs, has been evidenced in school-based PA interventions (237). To be sustainable, it may be critical that an intervention is integrated into a school environment with minimal disruption to the school schedule or common daily practices. Furthermore, any intended changes in behaviour brought about by intervention (i.e. reduced sitting time, increased PA) will need to influence either no change or a positive change in academic performance and on/off task behaviour if it is to have any chance of acceptance as a permanent classroom modification.
104
Despite these challenges, interventions promoting PA have been successfully implemented during physical education class, during break times, and before and after school hours (9,241). Furthermore, when PA has been used as a teaching tool as well as a short activity break during class time, positive effects have been observed in classroom management, student attention and focus on task (242).
1.14. Standing desks within the school classroom
Replacing traditional desks with standing desks is by no means a small modification to a primary school classroom. However, this type of intervention design has many promising characteristics, including:
- High potential daily intervention exposure time per day and over a full academic year
- The simple self-service design has little demand on teaching staff for implementation, compared to other common intervention designs (i.e. educational classes).
- The autonomous, subconscious nature of using standing desks removes the conscious effort of the user to engage in a healthy behaviour (standing) and to reduce the negative behaviour (sitting) (236)
- The user has the option to not only reduce total sedentary time but also frequently interupt prolonged bouts of sitting with standing or light ambulation. - A full classroom of standing desks, assuming they remain operational, can be
used by hundreds of children over a 5-10 year period, potentially making the intervention highly cost-effective.
When considering all these factors, further research into the effectiveness of this environmental restructuring strategy as a means to reduce sitting time in young people is warranted.