Calibrating physical activity intensity for hip-worn accelerometry in XXXX age 60 to 91 years: The @entity1 's Health Initiative OPACH Calibration Study.

@entity1 @entity26 @entity2270
OBJECTIVE: We conducted a laboratory-based calibration study to determine relevant cutpoints for a hip-worn accelerometer among @entity1 >= 60 years, considering both type and filtering of counts. METHODS: Two hundred @entity1 wore an ActiGraph GT3X+ accelerometer on their hip while performing eight laboratory-based activities. @entity26 uptake was measured using an Oxycon portable calorimeter. Accelerometer data were analyzed in 15-second epochs for both normal and low frequency extension (LFE) filters. Receiver operating characteristic (ROC) curve analyses were used to calculate cutpoints for sedentary, light (low and high), and moderate to vigorous physical activity (MVPA) using the @entity2270 and vector magnitude (VM) counts. RESULTS: Mean age was 75.5 years (standard deviation 7.7). The Spearman correlation between @entity26 uptake and accelerometry ranged from 0.77 to 0.85 for the normal and LFE filters and for both the @entity2270 and VM. The area under the ROC curve was generally higher for VM compared to the @entity2270 , and higher for cutpoints distinguishing MVPA compared to sedentary and light low activities. The VM better discriminated sedentary from light low activities compared to the @entity2270 . The area under the ROC curves were better for the LFE filter compared to the normal filter for the @entity2270 counts, but no meaningful differences were found by filter type for VM counts. CONCLUSION: The cutpoints derived for this study among @entity1 >= 60 years can be applied to ongoing epidemiologic studies to define a range of physical activity intensities.
