Twenty-four Hours of Sleep, Sedentary Behavior, and Physical Activity with Nine Wearable Devices.
Getting enough sleep, exercising, and limiting sedentary activities can greatly contribute to disease prevention and overall health and longevity. Measuring the full 24-h activity cycle-sleep, sedentary behavior (SED), light-intensity physical activity (LPA), and moderate-to-vigorous physical activity (MVPA)-may now be feasible using small wearable devices.


OBJECTIVE
This study compared nine devices for accuracy in a 24-h activity measurement.


METHODS
Adults (n = 40, 47% male) wore nine devices for 24 h: ActiGraph GT3X+, activPAL, Fitbit One, GENEactiv, Jawbone Up, LUMOback, Nike Fuelband, Omron pedometer, and Z-Machine. Comparisons (with standards) were made for total sleep time (Z-machine), time spent in SED (activPAL), LPA (GT3X+), MVPA (GT3X+), and steps (Omron). Analysis included mean absolute percent error, equivalence testing, and Bland-Altman plots.


RESULTS
Error rates ranged from 8.1% to 16.9% for sleep, 9.5% to 65.8% for SED, 19.7% to 28.0% for LPA, 51.8% to 92% for MVPA, and 14.1% to 29.9% for steps. Equivalence testing indicated that only two comparisons were significantly equivalent to standards: the LUMOback for SED and the GT3X+ for sleep. Bland-Altman plots indicated GT3X+ had the closest measurement for sleep, LUMOback for SED, GENEactiv for LPA, Fitbit for MVPA, and GT3X+ for steps.


CONCLUSIONS
Currently, no device accurately captures activity data across the entire 24-h day, but the future of activity measurement should aim for accurate 24-h measurement as a goal. Researchers should continue to select measurement devices on the basis of their primary outcomes of interest.
1Stanford Center on Longevity and Psychology Department, Stanford University, Stanford, CA; 2School of Nutrition and Health Promotion, Arizona State University, Phoenix, AZ; 3Stanford Prevention Research Center, Stanford University, Stanford, CA; and 4Cardiovascular Medicine, Stanford School of Medicine, Stanford University, Stanford, CA.
Mary E
ME
Rosenberger
Matthew P
MP
Buman
William L
WL
Haskell
Michael V
MV
McConnell
Laura L
LL
Carstensen
D056044:Actigraphy / Q000295:instrumentation* / Q000592:standards*; D000328:Adult; D000368:Aged; D015444:Exercise; D005260:Female; D000072936:Fitness Trackers; D006801:Humans; D008297:Male; D008875:Middle Aged; D057185:Sedentary Behavior; D012890:Sleep; D055815:Young Adult