Accuracy of inclinometer functions of the activPAL and ActiGraph GT3X+: A focus on physical activity.
Hyun-Sung An, Youngwon Kim, Jung-Min Lee
PMID 27780084WHAT IT FOUND
For healthy adults in short lab trials, thigh activPAL classified sitting and standing more accurately than waist or wrist ActiGraph.
All devices classified stepping well overall, but ActiGraph error was high for stairs and for walking while typing on the wrist.
Key findings
01The activPAL worn on the thigh was more accurate than the ActiGraph worn on the waist or wrist for sitting and standing activities, except stationary biking.
02For stepping, all three monitors had mean absolute percent error below 10.00%, except climbing stairs for the waist and wrist ActiGraph and walking 3 mph while typing for the wrist ActiGraph.
03The activPAL matched directly observed time for 7 activities, the waist ActiGraph matched for 5 treadmill activities, and the wrist ActiGraph matched for 3 treadmill activities.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study used healthy adults aged 18 to 40 years, so it does not show accuracy in older adults or patients with movement, balance, or posture problems. The activities were short, structured lab trials, not full-day free-living wear. Physical characteristics such as wrist, waist, thigh circumference, and leg length were not controlled. Only sitting, standing, and stepping were tested, so other postures and movements were not examined. The ActiGraph stepping estimate relied on a custom formula, because the built-in inclinometer did not measure stepping. The study did not test a treatment or patient outcome.
The easy way to misread this
Do not conclude that ActiGraph waist or wrist monitors can accurately classify sitting and standing in patients. The study found large errors for many sitting and standing tasks, and it was done in healthy adults doing short lab trials.