The Effects of the LiiNK Intervention on Physical Activity and Obesity Rates among Children.

Background: Obesity and inactivity among children are at an all-time high and have been steadily increasing in prevalence over the last thirty years. The school environment provides the ideal setting for reaching a large number of children across diverse populations in order to reverse these trends. However, there are many inconsistent results yielded by school-based physical activity interventions due to implementation length, time for activities, and the use of structured physical activities. The LiiNK Project^® is a whole-child intervention addressing these gaps by providing children 45-60 min of recess (unstructured, outdoor play) in their schools daily, while the control children are allowed to engage in recess for 30 min daily. The purpose of this study was to compare the physical activity intensity and obesity rates of third- and fourth-grade children participating in the LiiNK intervention, which provides 60 min of recess for third graders and 45 min for fourth graders, to those in a control group allowed 30 min of daily recess.

Methods: The children were 8-10 years old (M = 9.2; 52% females and 48% males). The intervention children comprised 90 third graders and 100 fourth graders, and the control children comprised 101 third graders and 92 fourth graders. Physical activity levels were monitored using accelerometers to assess sedentary, light, and moderate-to-vigorous physical activity (MVPA). Obesity rates were evaluated using bio-electrical impedance analysis (BIA), in which body fat percentage is calculated based on normative values using age and sex in the equation.

Results: The third-grade intervention children engaged in 13 more MVPA minutes and took 900 more steps daily than their control counterparts, and also presented a greater proportion of overweight children transitioning to a healthy weight status from the fall to the spring semester. Conversely, the fourth-grade control children increased their activity by 500 steps and 15 more MVPA minutes daily. Despite this, the intervention children overall demonstrated a reduction in body fat percentage, while the control children demonstrated an increase in body fat percentage.

Conclusions: Ultimately, 60 min of unstructured, outdoor play in schools provides children the best opportunity to engage in MVPA, which may positively impact body fat percentages, offering a potential strategy for combatting childhood obesity in school settings.