| Isotemporal Substitution Analysis of Accelerometer-derived
Sedentary Behavior, Physical Activity Time, and Physical
Function in Older Women: A Preliminary Study |
| Mi-Ji Kim |
| Tokyo Metropolitan Institute of Gerontology |
| Correspondence |
Mi-Ji Kim , Tel: +81-80-4459-1881, Fax: +81-3-3964-2316, Email: mijiak@tmig.or.jp
|
|
|
Received: October 1, 2015; Accepted: November 12, 2015. Published online: November 30, 2015. |
|
|
|
| ABSTRACT |
PURPOSE:
In this pilot cross-sectional study, we aimed to examine associations of objectively derived sedentary and physical activity time
with physical function using an isotemporal substitution approach in older adults.
METHODS:
We enrolled 101 community-dwelling elderly Japanese women (mean age: 81.4±2.8 years; range: 76-89 years). Physical activity
was objectively measured with an accelerometer (ActiGraph GT3X+) worn around the waist for waking hours for 10 consecutive days. We
examined the effects of replacing prolonged sedentary time (accumulated in bouts ≥30 min) with non-prolonged sedentary, light-intensity,
and moderate-to-vigorous physical activity (MVPA), on physical function (usual and maximum gait speeds, 5-chair sit-to-stand and timed
up-and-go tests) using an isotemporal substitution model. Multivariable linear regression was used to determine associations between
measures of sedentary behavior (SB), physical activity time, and physical function.
RESULTS:
Subjects wore the accelerometers for an average of 9 days and 954.6 minutes daily; the total volume of physical activity was 174.7
CMP/day. The timed up-and-go test results (B=-0.468; 95% confidence interval; CI=-0.824 to -0.112) were significantly associated with the
combination of lower mean prolonged sedentary time (<30 min/day) and higher mean non-prolonged sedentary time (>30 min/day). Replacing
sedentary time with MVPA time yielded favorable improvements in usual gait speed (B=0.240; 95% CI=0.133 to -0.346), maximum gait speed
(B=0.240; 95% CI=0.105 to -0.375), and timed-up-and-go test results (B=-0.264; 95% CI=-3.557 to -0.970).
CONCLUSIONS:
Replacing sedentary time with an equal amount of MVPA time was associated with favorable physical function in older adults.
The patterns of SB were differentiated beyond just functional mobility, including prolonged and non-prolonged sedentary time. Such findings
are important in designing effective lifestyle interventions targeting older adults. |
| Key words:
sedentary, physical activity, isotemporal, physical function, older adults |
|
|
|
PDF Links
Full text via DOI
Download Citation 
