Mike: Hello, I'm Mike Clarke, podcast editor for the Cochrane Library. Identifying ways to help people be physically active should help improve their health and well-being, and prevent premature deaths. There are several relevant Cochrane reviews and one published in September 2021 looks at school-based programs. Here's the review's first author, Sarah Neil-Sztramko, from McMaster University in Canada to tell us about the importance of the review and its findings.

Sarah: Maintaining a physically active lifestyle from childhood to adulthood is very important. Worldwide, it's estimated that 5.3 million deaths are caused every year by insufficient exercise and a lack of physical activity also contributes to several chronic diseases and even cancer.
Research tells us that a person's pattern of physical activity in childhood leads to similar patterns in adulthood. Therefore, given how much time children spend in school in most of the world, programs that aim to incorporate physical activity into the school setting might help to boost children's overall physical activity, regardless of outside factors, such as parents' behaviours or financial situation. We did this review to find out if this is true and found that the evidence is mixed.
Through our review, we investigated whether promoting physical activity in the school setting resulted in increases in the proportion of students meeting physical activity guidelines, the number of minutes per week spent in moderate to vigorous physical activity and the amount of time spent sitting down. We also looked to see whether the programs improved students' physical fitness, quality of life, body weight or body mass index, BMI for short, and led to any adverse events.
We found 89 studies from around the world that included more than 66,000 children and adolescents between the ages of six and 18. To be included in our review, the physical activity program must have been implemented for at least 12 weeks, but some programs were up to six years long.
Across the 89 studies, no two programs were alike, which makes it difficult to compare across studies. In general, the programs fell into one of four groupings: before and after school programs; enhanced physical education programs; programs that incorporated physical activity into the school day; and multicomponent programs, which took a whole-school approach to change educational materials, the school environment and sometimes the school curriculum.
Across the studies, we found that school-based physical activity interventions probably result in little to no increase in time engaged in moderate to vigorous physical activity. The mean difference across studies was an increase of less than one minute per day. These programs may also lead to little or no decrease in sedentary time, but we are less certain about these findings.
The evidence does suggest that school-based physical activity programs may improve levels of physical fitness and provide a small decrease in BMI but, again we have low certainty in these effects given the wide variability in studies and their quality. Finally, turning to quality of life and adverse events, we're very uncertain about the effects of the programs on these because they were measured in so few studies.
In secondary analyses, we looked to see whether the results differed between the four broad intervention categories. We found that multicomponent interventions and interventions that incorporate physical activity throughout the school day may increase overall physical activity, but the effect appears to be small. Conversely, enhanced physical education programs may significantly affect physical fitness.
In summary, while school-based physical activity programs may increase fitness and have a small impact on BMI, they probably do not increase physical activity over the whole week. Given how different each program is and the wide variation in the effects seen across studies, public health practitioners, teachers and decision-makers who may be implementing physical activity programs in a school setting should give careful consideration to the program used.

Mike: Thanks Sarah, If you would like to find out more by reading the full review, you can find it with a search for 'school-based physical activity' on Cochrane Library dot com.