Study: Extra Phys-Ed Classes Have No Impact on Obesity

Allowing kids more exercise during the school day has been hailed as one of the most effective interventions aimed at slowing down and even fully controlling the epidemic of childhood obesity. However, according to a paper published in the British Medical Journal, the impact of the extra physical activity classes was found to be “small, almost negligible.”

Medical News Today reports that researchers from Plymouth and Exeter Universities in the UK ran a meta-analysis on all the papers studying the effects of interventions aimed at increasing the activity levels of students aged 16 and under. In all, researchers looked at 30 such studies performed between the 1990 and 2012. Once the results of the targeted studies were adjusted for age, gender, and physical activity prior the commencement of the research, there appeared to be no significant impact on physical activity at all.

One of the studies they reviewed was of an intervention in the US that sought to increase physical activity in 729 youngsters of average age 11 by giving them three 90-minute after-school sessions per week. Each session included 60 minutes of high intensity physical activity.

But the results were disappointing: measures taken half way through the trial showed in terms of total activity, the children were only doing an extra five minutes of walking or running per day, and by the end of the trial, even these few minutes had gone down to zero.

The BMJ paper concludes that, in total, the studies showed an increase in physical activity that amounted to no more than about 4 minutes of jogging or brisk walking a day — not nearly enough to have any impact on the children’s BMI. The results had confirmed the findings of several previous studies that concluded that such interventions aren’t useful in bringing down obesity rates since they encourage kids to consume more calories to offset the extra effort.

The authors suggest another reason for the failure to impact BMI: the interventions could be displacing equally active periods, such as after-school clubs, which would usually take place outdoors.

While it is understandable for us to jump to the conclusion that the answer to the obesity crisis in kids is to make them do more exercise, the authors suggest we think carefully first, and urge future studies to take into account the effect of any interventions on whole day activity as well as activity-specific periods, as “small increase gained from formal interventions seems insufficient to improve the body mass / fat of children.”