The Influence of Accelerometer Cut Points on Determining the Percent of Preschool-Age Children Meeting Physical Activity Guidelines

Reduced physical activity is thought to be a major contributor to energy imbalance and obesity in children and adolescents. A challenge for researchers is selecting a tool that will accurately measure physical activity, especially in young children. A current tool that is used is an accelerometer. This study had two objectives. The first examined if different sets of accelerometer cut points developed for preschool-age children would produce the same physical activity results when identical raw data were run through them. Through the use of accelerometer data the second objective aimed to determine the percent of children who met the physical activity guidelines for 3 to 5 year olds, which recommend 180 minutes of combined light to vigorous activity each day. Participants wore accelerometers for 7 consecutive days. Raw accelerometer data were run through five sets of accelerometer cut points. A paired t-test was used to compare the minutes per day reported in sedentary, light, moderate to vigorous, and light to vigorous physical activity. The light to vigorous results calculated from the five sets of cut points were used to determine the percent of children who were meeting the physical activity recommendation. While some of the cut points when compared against each other did produce equal results within a particular physical activity threshold, no overall sets of cut points produced the same levels of physical activity across all activity thresholds. Two sets of cut points classified the same percent of participants (10.67%) as achieving the recommended 180 minutes of activity. A large range of participants (87.33%-0.33%) met the recommendations based on the other sets of cut points. The cut points chosen to process raw accelerometer data influenced the reported levels of physical activity