Measuring physical activity with accelerometers for individuals with intellectual disability: A systematic review.

Willie and the team read every paper that used hip-worn accelerometers with people who have intellectual disability.

They hunted for how long the devices were worn, where they were placed, and how many people actually kept them on.

The search covered 17 years and 42 studies, but no two teams followed the same rules.

Wear-time rules were all over the map. Some asked for 8 hours, others 10, a few wanted 12.

The big headache was compliance. Many adults took the belt off early or forgot to put it back on after a shower.

Because of this, the authors say we need one clear, simple protocol everyone can follow.

Arnold et al. (2026) answered the call. They tried the standard 10-hour rule on the adults with ID. Two-thirds hit the target and the data showed clear weekday versus weekend steps.

Ferguson et al. (2020) went further. They turned ActiGraph hip steps into calories with a short math formula made for adults with Down syndrome.

Lennon et al. (2015) ran a mirror review for adults with cerebral palsy. They also found that only some tests work, echoing the need to pick tools that fit the disability.

Patton et al. (2020) checked another battery and again saw poor reliability on several items, underlining the same message: choose proven parts, drop the rest.

You can stop guessing. Use the 10-hour wear rule from Arnold et al. (2026) and you will get usable data two-thirds of the time. If you need calories, plug the Ferguson et al. (2020) equation into Excel. Pick one protocol, teach it the same way every session, and check the belt at each visit. Consistency beats fancy gear.