Accelerometer Substudy

​Among those retiring in 2016-2019 physical activity and sleep will be objectively recorded 24 hours a day for a continuous 7-day period with a wrist-worn tri-axial ActiGraph wActiSleep-BT accelerometer at 18 and 6 months pre and 6 and 18 months post retirement. Estimated number of participants is 1000.

During the clinical visit, another accelerometer (Axivity Ltd, AX3) is fixed on participant’s thigh with water-resistant film. This thigh measurement captures better movement of lower extremities (e.g. sitting/standing, cycling) and provides opportunities for validation between devices.