The purpose of this study was to examine the accuracy of uni- and triaxial accelerometers in monitoring step counts and gait intensity in older people who did or did not use an assistive device. Forty-nine healthy and frail older adults wore uniaxial (Lifecorder, Suzuken Co. Ltd.) and triaxial accelerometers (Activity Monitor, Matsushita Electronic Works, Ltd., and Active Style Pro, Omron Healthcare Co., Ltd.) during three trials at different gait speeds. All accelerometers gave relatively accurate step counts for healthy older participants compared with direct observation; however, the error was greater for frail older people with assistive devices. Gait intensity detection error was unaffected by gait speed. Among frail older people with assistive devices, the gait intensity error was smaller than for step count error. To accurately assess the steps walked or the gait intensity among frail older people using assistive devices, more study is needed on these groups of participants.
Jonghoon Park, Kazuko Ishikawa-Takata, Sachiko Tanaka, Kyoko Bessyo, Shigeho Tanaka and Toshihide Kimura
Sachiko Inoue, Takashi Yorifuji, Masumi Sugiyama, Toshiki Ohta, Kazuko Ishikawa-Takata and Hiroyuki Doi
Few epidemiological studies have examined the potential protective effects of physical activity on insomnia. The authors thus evaluated the association between physical activity and insomnia in a large population-based study in Shizuoka, Japan. Individual data were obtained from participants in an ongoing cohort study. A total of 14,001 older residents who completed questionnaires were followed for 3 yr. Of these, 10,211 and 3,697 participants were eligible for the cross-sectional and longitudinal analyses, respectively. The authors obtained information about the frequency of physical activity and insomnia. Then, the adjusted odds ratios and 95% confidence intervals between physical activity and insomnia were estimated. Habitual physical activity was related to lower prevalence of insomnia. Frequent physical activity also reduced the incidence of insomnia, especially difficulty maintaining sleep. For elderly people with sufficient mobility and no preexisting disease, high-frequency physical activity (e.g., 5 or more days/wk) may help reduce insomnia.
Yuki Hikihara, Shigeho Tanaka, Kazunori Ohkawara, Kazuko Ishikawa-Takata and Izumi Tabata
The current study evaluated the validity of 3 commercially-available accelerometers to assess metabolic equivalent values (METs) during 12 activities.
Thirty-three men and thirty-two women were enrolled in this study. The subjects performed 5 nonlocomotive activities and 7 locomotive movements. The Douglas bag method was used to gather expired air. The subjects also wore 3 hip accelerometers, a Lifecorder uniaxial accelerometer (LC), and 2 triaxial accelerometers (ActivTracer, AT; Actimarker, AM).
For nonlocomotive activities, the LC largely underestimated METs for all activities (20.3%–55.6%) except for desk work. The AT overestimated METs for desk work (11.3%) and hanging clothes (11.7%), but underestimated for vacuuming (2.3%). The AM underestimated METs for all nonlocomotive activities (8.0%–19.4%) except for hanging clothes (overestimated by 16.7%). The AT and AM errors were significant, but much smaller than the LC errors (23.2% for desk work and –22.3 to –55.6% for the other activities). For locomotive movements, the 3 accelerometers significantly underestimated METs for all activities except for climbing down stairs.
We conclude that there were significant differences for most activities in 3 accelerometers. However, the AT, which uses separate equations for nonlocomotive and locomotive activities, was more accurate for nonlocomotive activities than the LC.