The Impact of Long-term School-based Physical Activity Interventions on Body Mass Index of Primary School Children

A Meta-analysis of Randomized Controlled Trials

Hong Mei; Yuelin Xiong; Shuixian Xie; Siyu Guo; Yukun Li; Bingbing Guo; Jianduan Zhang


BMC Public Health. 2016;16(205) 

In This Article


The epidemic of childhood obesity has become a serious public health concern[1] due to its short and long-term physical and psychological consequences[2–4] and related economic burdens.[5] Results from the Global Burden of Disease Study 2013 indicated that in developed countries, 23.8 % of boys and 22.6 % of girls were overweight/obese; and in developing countries, the corresponding rates were 12.9 % and 13.4 % respectively.[6] Given the difficulties involved in weight loss,[7] and the costly treatment of obesity,[8] initiating obesity prevention at an early age has reached global consensus.

Regular physical activity (PA) established during childhood may lay the foundation for lifelong fitness.[9] Children with insufficient PA are at a higher risk to be overweight/obese and this risk increases with age.[10] Therefore, PA is considered as one of the most important obesity intervention strategies.[11,12] To promote PA of children through the school setting has its merits compared to the household and the community environment,[13–15] because children are better organized and can be collectively reached at school.[16,17] As all individuals are at risk of gaining extra weight,[18] school-based PA intervention should target all students regardless of their weight status. This also avoids the possible stigma caused by only putting the overweight/obese students into the spotlight.[19]

Several studies have reported the impact of school-based PA interventions on students' obesity problems, yet failed to yield consistent conclusions.[20–24] Recently research revealed that school-based PA interventions were ineffective on reducing the BMI increment in primary school students,[25] while some others held the opposite conclusion.[26,27] The inconsistency of the conclusions may result from the variation in study characteristics (study population, age, gender, and sample size), study design, intervention duration, strategies, etc. For instance, the TrimTots programme, involving randomized controlled trials (RCTs) of PA interventions in preschool and primary school age children, indicated a significant reduction in obesity risk after a long term follow-up;[28] while the results from the ECLS-K study, an earlier childhood longitudinal study in primary school, demonstrated that physical education has no significant impact on BMI if the students had a normal weight/overweight status.[29] A recently published systematic review by the Cochrane Collaboration demonstrated the positive impact of school-based PA interventions on students' behavior and on physical measurements.[30] However, since the studies used in the review possessed wide spans in the participants' age (from 6 to 18 years) and in the intervention duration (from 12 weeks to 6 years), the authors suggested the results should be interpreted with caution. In addition, Paulo et al also suggested that the impact of PA programs in promoting fitness of children should not be generalized because of the variation in duration of the PA programs and intensity and type of PA among studies.[31]

Furthermore, in consideration of the out-of-school impact, e.g., holiday recess might compromise the effects from school days,[32] and because fostering healthy lifestyle habits is a long-term process,[33,34] we suspect that long-term PA interventions directed at young students may yield more robust and convincing results. In the present meta-analysis, with stringent inclusion criteria, we aimed to more precisely and holistically understand whether long-term school-based RCT PA interventions could benefit primary school children's growth; and a further aim was to investigate if the study area, design and quality, intervention duration, weekly PA intervention time, PA intervention type, and measurement could lead to the significant benefits.