An automatic device to measure time spent upright

Abstract

Objective measurements of time spent standing or walking would be of benefit in assessing response to therapy. We have tested a device consisting of a mercury tilt switch attached to an electronic counter to measure time spent upright. Eleven subjects, six male and five female age 67-88 years (mean 76 years) undergoing rehabilitation were studied. Diagnoses included: Parkinson's disease, dementia, stroke and femoral fracture. The device was fitted with the tilt switch on the lateral aspect of thigh. Measurements compared stopwatch readings made by an observer and the device. Study periods were of one to three hours. There was excellent correlation between stopwatch and device measurements of time spent standing (t = 0.994; p < 0.001). The device functioned well during physiotherapy and ward activities although measurements were inaccurate when subjects used an exercise bicycle or climbed steps greater than 20 cm in height. The device should prove useful for monitoring activity and response to mobilization therapy.