You purchased a wristband or watch for exercise monitoring and aided by training and nutrition adjustment data, but are the numbers on the monitor reliable and accurate? New research has examined the range of error of 7 common bracelets – by Rotem Keslo-Cohen, Physiological Effort at the Center for Sports Medicine and Research, Wingate Institute
Smart Sport/Combat watches and bracelets for monitoring activity that measure pulse, caloric expenditure, several daily steps, are common among the general public today. More and more people are wearing these watches and are using the data when planning workouts, controlling calorie expenditure, dietary adjustment and maintaining a healthy lifestyle.
Given the wide variety of existing instruments, we must ask ourselves what the accuracy of these measures is? Although in most cases the device manufacturers report a high level of accuracy, these facts have not yet been tested in a controlled and independent research environment against valid measurement methods.
Recently, a study was carried out by a group of researchers at Stanford University that looked at the accuracy of measuring the pulse response and energy expenditure of seven common and common commercial bracelets. The bracelets tested are: Apple watch, Basis Peak, Fitbit Surge, Microsoft Band, Mio Alpha 2, PulseOn
and Samsung Gear S2.
These bracelets were selected for testing after meeting a number of criteria defined by the researchers: arm-worn bracelets with continuous pulse-measuring capability, a battery lasting for more than 24 hours, and immediately available bracelets.
Some 60 subjects (29 men and 31 women) aged 64-21 years participated in the study, who made various efforts at different intensities (sitting, walking, running and cycling). During the test protocol, the subjects were monitored by the ECG system for the purpose of examining the pulse response and direct oxygen consumption was measured by a metabolic measurement system to assess the energy expenditure. The data collected in the laboratory measures were compared with the bracelet data. Each subject wore up to 4 bracelets on his arm during the assessment, and each protocol was tailor-made for the individual according to their fitness level.
Findings: The pulse is accurate, but the energy expenditure – much less!
The results of the study showed that in a heterogeneous group of people: Most of the bracelets reported relatively accurately the pulse values with an error range of less than 5% (acceptable error range), (it is important to note that this error range is found when cycling – an activity where the body moves Upper are relatively few, in walking or running, the error range was up to about 9% in some devices). In contrast, none of the bracelets tested exhibited energy expenditure (calories) accurately. The devices tested showed a very large error range, even the most accurate clock still showed a range of error of about 27%, while the least accurate clock of seven – presented a range of error close to 90%.
It is important to note that the measurement error increased as the intensity of the effort increased in each of the activities performed: cycling, walking and running. Factors such as dark skin color, wrist circumference, and high BMI value increased measurement error. That is, if dark skin color, I have a high BMI and exert high intensity effort, there is a high probability that all seven bracelets tested to accurately estimate the energy cost of the effort I made will be very low.