Comparison of two sets of accelerometer cut-off points for calculating moderate-to-vigorous physical activity in young children.

Accelerometers are becoming more widely used in the assessment of physical activity in children, and converting the output to min of moderate-to-vigorous physical activity (MVPA) requires the use of age-specific cut-off point definitions. However, numerous cut-off points are available among children, and different cutoff point definitions of MVPA have been used in different studies. Comparison between studies may therefore be difficult, and conclusions drawn from studies may be inaccurate. Guinhouya et al. found significant differences between the 2 most commonly used accelerometer cut-off points for moderate-to-vigorous physical activity (MVPA) in 8- to 11-year-old children. 1 This finding confirms that the differences between the 2 cut-off points are large and meaningful and, depending on what cut-off point is used, yield vastly different results, which may misclassify children according to their physical activity. Guinhouya and colleagues’ study is the first to report the differences in MVPA, which is important because it allows compliance with current US, UK, and Australian physical activity recommendations for children to be evaluated. 2-4 Further, it highlights the urgent need for physical activity researchers to test the validity of different cut-off points and report variations between them for different age groups. Our aim was to examine discrepancies in categorizing MVPA for preschool children using the accelerometer cut-off point definitions reported by Sirard 5 (MVPA S ) and Puyau 6 (MVPA P ).