The purpose of this investigation was to develop cut-points for the Actical accelerometer in adults that correspond to light, moderate, and vigorous physical activity using a percentage of maximal oxygen uptake (VO2max). Twenty five young adults completed a progressive submaximal exercise test on a treadmill wearing an Actical accelerometer while oxygen uptake was measured. The VO2max based cut-points for light-to-moderate was 4952 counts per minute (cpm), for moderate-to-vigorous intensity was 9714 cpm. VO2 based cut-points were significantly greater than MET based cut-points. The results of this investigation suggest that MET definitions of moderate and vigorous intensity are too light for young adults and may lead to misclassification of physical activity levels. The results also suggest that individual calibration of the Actical accelerometer may be needed due to the high variability of VO2max based cut-points
