The purpose of the study was to investigate whether a 24-hr recording period is sufficient to describe physical activity (PA) of 1 week for intraindividual comparison in older adults. Furthermore, the authors analyzed whether physical performance can be used as a surrogate marker of PA. PA was captured on 7 consecutive days by a body-fixed sensor in 44 community-dwelling older adults (80.75 ± 4.05 yr). Mean times of walking and of “time on feet” of the group were 10.2 hr (± 3.5) and 35.1 hr (± 9.43), respectively. Intraindividual variabilities of walking and of time on feet were 31.9% ± 10.79% and 19.4% ± 8.76%, respectively. Accumulated time of variables of PA showed no differences between weekdays, with variabilities of 3.8% and 1.8% for walking and time on feet, respectively. Association between Short Physical Performance Battery and PA was limited (walking r = .397, time on feet r = .41).
Nicolai, Benzinger, Becker, and Lindemann are with the Dept. of Clinical Gerontology, Robert Bosch Hospital, Stuttgart, Germany. Skelton is with the School of Health and Social Care, Glasgow Caledonian University, Glasgow, UK. Aminian is with the Interfaculty Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.