Calibration of the GENEA accelerometer for assessment of physical activity intensity in children.

OBJECTIVES The purpose of the study was to establish activity intensity cut-points for the GENEA accelerometer via calibration with oxygen consumption (V˙⁡O(2)). DESIGN The study was a lab-based validation and calibration study. METHODS Forty-four children, aged 8-14 years, completed eight activities (ranging from lying supine to a medium paced run) whilst wearing GENEA accelerometers at three locations (each wrist and at the right hip), an ActiGraph GT1M at the hip and a portable gas analyser. ActiGraph output and V˙⁡O(2) were used for assessment of concurrent and criterion validity, respectively. Pearson's r correlations were used to assess validity of the GENEA monitors at each location and location-specific activity intensity cut-points were established via Receiver Operator Characteristic curve analysis. RESULTS The GENEA showed good criterion validity at both wrist locations (right: r=.900; left: r=.910, both p<0.01), although the hip-mounted monitor demonstrated significantly higher criterion validity (r=.965, p<0.05). Similar results were shown for concurrent validity (right: r=.830; left: r=.845; hip: r=.985, all p<0.01). GENEAs, irrespective of wear location, accurately discriminated between all activity intensities (sedentary, light, moderate and vigorous) with the hip mounted monitor recording the largest area under the curve for each intensity (area under the curve=0.94-0.99). CONCLUSIONS The GENEA can be used to accurately assess children's physical activity intensity when worn at either the wrist or the hip.