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Background: Accurate measurement of physical activity patterns can be used to identify sedentary behaviour and may facilitate interventions aimed at reducing inactivity. Objective: To evaluate the activPAL physical activity monitor as a measure of posture and motion in everyday activities using observational analysis as the criterion standard. Methods: Wearing three activPAL monitors, 10 healthy participants performed a range of randomly assigned everyday tasks incorporating walking, standing and sitting. Each trial was captured on a digital camera and the recordings were synchronised with the activPAL. The time spent in different postures was visually classified and this was compared with the activPAL output. Results: Intraclass correlation coefficients (ICC 2,1) for interdevice reliability ranged from 0.79 to 0.99. Using the Bland and Altman method, the mean percentage difference between the activPAL monitor and observation for total time spent sitting was 0.19% (limits of agreement -0.68% to 1.06%) and for total time spent upright was -0.27% (limits of agreement -1.38% to 0.84%). The mean difference for total time spent standing was 1 .4% (limits of agreement -6.2% to 9.1%) and for total time spent walking was -2.0% (limits of agreement -16.1% to 12.1%). A second-by-second analysis between observer and monitor found an overall agreement of 95.9%. Conclusion: The activPAL activity monitor is a valid and reliable measure of posture and motion during everyday physical activities. [ABSTRACT FROM AUTHOR]

Background: The accurate measurement of physical activity is crucial to understanding the relationship between physical activity and disease prevention and treatment. Objective: The primary purpose of this study was to investigate the validity and reliability of the activPAL physical activity monitor in measuring step number and cadence. Methods: The ability of the activPAL monitor to measure step number and cadence in 20 healthy adults (age 34.5± 6.9 years; BMI 26.8 ±4.8 (mean±SD)) was evaluated against video observation. Concurrently, the accuracy of two commonly used pedometers, the Yamax Digi-Wolker SW-200 and the Omron HJ-109-E, was compared to observation for measuring step number. Participants walked on a treadmill at five different speeds (0.90, 1.12, 1.33, 1.56, and 1 .78 m/s) and outdoors at three self selected speeds (slow, normal, and fast). Results: At all speeds, inter device reliability was excellent for the activPAL (ICC (2,1 )⩾0.99) for both step number and cadence. The absolute percentage error for the acfivPAL was <1 .11% for step number and cadence regardless of walking speed. The accuracy of the pedometers was adversely affected by slow walking speeds. Conclusion: The acfivPAL monitor is a valid and reliable measure of walking in healthy adults. Its accuracy is not influenced by walking speed. The activPAL may be a useful device in sports medicine. [ABSTRACT FROM AUTHOR]