Energy expenditure monitors are being aggressively marketed to the general public. We have quite a few choices, such as, the Fitbit One, Fitbit Zip and ActiGraph worn on the belt, the Bodymedia FIT armband worn on the left arm, the Jawbone Up, NikeFuel and Basis B1 band worn on the wrist and the DirectLife monitor worn around the neck. The cost of these physical activities measuring monitors can range from $100 to $300. Which monitor is the most accurate? Are these monitors worth the money?
A 2013 study out of the University of Nebraska and Iowa State University examined the validity of the above monitors with 30 healthy women and 30 healthy men, ages 18-43 years performing 13 different physical activities in a routine. The activities were treadmill walking at 2.5 mph, treadmill brisk walking at 3.5 mph, self-paced overground walking, self-paced overground walking with 33 pound backpack, treadmill jogging at 5.5 mph, treadmill running at 6.5 mph, ascending and descending stairs, stationary cycling, elliptical exercise, Wii tennis play and playing basketball with researchers.
A portable metabolic analyzer, the OM, measured oxygen consumption of each participant during activity and was used in the study as the criterion measure. The results of the testing supported the validity of the energy estimates from the BodyMedia FIT armband. The Fitbit Zip came in second and the Nike+Fuel band must be viewed with caution due to inconsistent findings. All three of these monitors show more potential than the other listed monitors.
The other study, at the University of Tennessee, was to determine if location of where a monitor is worn makes a difference in accuracy. The Nike Fuelband (NFB), Fitbit (FB) and ActiGraph GT3X (AG) were used in this study. Twenty-one healthy college-aged adults wore a NFB on the right wrist, a FB on the left hip and AG on the right hip while performing 17 activities. The results of the study demonstrated the NFB overestimated physical activity energy expenditure during most activities with arm movements and sport activities. The hip-worn AG and FB overestimated walking and underestimated activities with arm movements. In conclusion, the wrist-worn NFB had similar accuracy to the waist-worn monitors. However, none of the monitors were able to accurately estimate energy expenditure of a range of activities from walking to basketball.
Sources:
Lee J, Youngwon K, Welk G. Validity of Consumer-Based Physical Activity Monitors. University of Nebraska and Ohio State University. 2013
Ceaser T, Thompson D,FACSM, Bassett Jr., D, FACSM. Estimation of Caloric Expenditure Using Triaxial Accelerometers. May 2013.
