Measuring compliance with IOM guidelines for preschoolers' physical activity: Complications and solutions

Background: The Institute of Medicine (IOM) recently released PA recommendations for preschool-age children (3-5yrs), which if followed, should yield improvements across a myriad of health outcomes over time. IOM's recommendation is preschoolers' spend 15 minutes/hour (25% of waking hours) being physically active (light-vigorous, total PA). This represents the first known national-level recommendation to employ evidence from studies using accelerometers to measure PA. Hence, this recommendation offers researchers, practitioners, and policy makers a single, evidence-based objective benchmark for assessing preschoolers' PA.

Complication: Objective measurement of preschoolers' PA via accelerometry produces vastly different estimates of PA due to differences in cutpoints used to define PA intensity levels. The majority (4/6) of studies informing IOM's 15min/hr guideline used a single set of cutpoints. This creates confusion, since there are currently 6 cutpoints used with this population.

Solutions: When collecting accelerometer-based PA to evaluate compliance with IOM's PA guideline, both researchers and practitioners need to: 1) use the same Reilly et al cutpoints as used by IOM to distill accelerometer data into estimates of total PA; 2) develop conversion equations that allow comparisons among estimates of total PA across different cutpoints; and 3) consider comparing additional measures of time spent physically active, such as pedometers, to total PA estimates derived from accelerometry.

Conclusion: The IOM's recommendations represent a major step forward in establishing PA guidelines from studies employing state-of-the-art measures. However, this is not without complications. These solutions will help unify approaches for monitoring preschoolers' PA.