Measuring physical activity with pedometers in older adults with intellectual disability: reactivity and number of days.
Four pedometer days give a stable weekly step count for older adults with ID—no practice days needed.
01Research in Context
What this study did
The team clipped pedometers to older adults with intellectual disability. They wanted to know if the device changed walking (reactivity) and how many days you need for a solid weekly count.
What they found
No one walked more just because the pedometer was there. Any four days gave the same weekly total with 96% reliability.
How this fits with other research
Leung et al. (2017) later showed that wear-time rules for activity trackers are all over the place, so this four-day rule is a rare clear guide.
Arnold et al. (2026) switched to accelerometers and still found the standard wear-time works for adults with ID, building on the four-day idea.
Shawler et al. (2021) saw the opposite: teens with moderate or severe ID walked extra on Day 1 and dropped on Day 7, showing reactivity. The clash makes sense—teens react, older adults don’t.
Why it matters
You can trust a four-day pedometer sample for older adults with ID and skip long baselines. If you work with teens or more severe ID, add a practice day and toss the last day to avoid the bounce shown by Shawler et al. (2021).
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02At a glance
03Original abstract
The minimum number of days of pedometer monitoring needed to estimate valid average weekly step counts and reactivity was investigated for older adults with intellectual disability. Participants (N = 268) with borderline to severe intellectual disability ages 50 years and older were instructed to wear a pedometer for 14 days. The outcome measure was steps per day. Reactivity was investigated with repeated measures analysis of variance, and monitoring frame was assessed by comparing combinations of days with average weekly step counts (with intraclass correlation coefficients [ICCs] and regression analyses). No reactivity was present. Any combination of 4 days resulted in ICCs of 0.96 or higher and 90% of explained variance. The study concludes that any 4 days of wearing a pedometer is sufficient to validly measure physical activity in older adults with intellectual disability.
Intellectual and developmental disabilities, 2012 · doi:10.1352/1934-9556-50.4.343