Purpose This study aimed to determine whether placing a second activPAL monitor on the
torso would allow the detection of seated versus lying postures. Methods Fifteen healthy
adults (18-55 yr of age) wore an activPAL on the right thigh and another activPAL over the
right rib cage. Both monitors were synchronized and initialized to record data in 15-s
epochs. Participants performed a semistructured routine of activities for 3 min each. Activities
included lying down (while supine, prone, and on the side), sitting, standing, sweeping …

ABSTRACT BASSETT, DR Jr., D. JOHN, SA CONGER, BC RIDER, RM PASSMORE, and JM
CLARK. Detection of Lying Down, Sitting, Standing, and Stepping Using Two ActivPAL
Monitors. Med. Sci. Sports Exerc., Vol. 46, No. 10, pp. 2025–2029, 2014. The activPAL is an
accelerometer-based monitor worn on the thigh that classifies daily activities into three
categories (sitting/lying down, standing, and stepping). The monitor discriminates between
sitting/lying and the upright position by detecting the inclination of the thigh. It detects …