to participate . All participants followed the same testing protocol which consisted of resting in a supine position ( 5mins ), then sitting ( 5mins ), standing ( 5mins ), Bruce treadmill protocol ( 9mins ), sitting ( 5mins ), cycling at 25 Watts on a stationary bike ( six 3-minute stages ) and then sitting ( 5mins ). Subjects repeated the above testing protocol twice , wearing two of the wrist monitors ( one on each wrist ) during each visit . There was a seven day break between the two exercise protocols .
Maximal oxygen consumption ( VO 2 max ) was assessed via indirect calorimetry , with the gas analysers ( O 2 and CO 2
) and volume calibrated prior to each test . A portable gas analysis system ( MetaMax 3B ) was used to asses expired gases to estimate energy expenditure during the test protocols . A 3-lead ECG was used to determine continuous heart rate during the test protocols . The four watches were individualised according to the manufacturer ’ s instructions for the individual ’ s age , gender and anthropometrical data .
Results : All of the participants completed all of the assessments . With regard to heart rate , the most accurate of the watches ( compared to simultaneous ECG ) was the Apple Watch which was only ( on average ) 1.3bpm lower than the ECG . The other heart
The 30-second article
• Researchers investigated the accuracy of four popular wrist-worn monitors ( Apple Watch , FitBit Charge HR , Samsung Gear S and Mio ALPHA ) with regard to heart rate and energy expenditure .
• For the study , 22 active individuals aged in their mid-20 ’ s underwent a testing protocol comprising a series of resting postures and physical activities
• The data recorded by the four activity trackers was compared with that recorded by highly accurate laboratory standard apparatus
• All four devices underestimated heart rate by a relatively small amount ( between 1 and 9 per cent ) and energy expenditure by a far larger degree ( between 9 and 43 per cent ).
Given the devices all underestimated heart rate , caution should be exercised when advising clients who may be at risk during higher intensity exercise to base their heart rate upon these devices .
rate watches also underestimated the actual ( ECG ) heart rate by varying degrees : Mio ALPHA ( -4.3bpm ); Samsung Gear S ( -7.1bpm ); and the FitBit Charge HR ( -9.3bpm ).
With regard to energy expenditure for the test protocol , all of the devices underestimated the actual energy expenditure . The most accurate was the Samsung Gear S , which only underestimated the true energy expenditure by approximately -9 per cent . This was followed by the FitBit Charge HR ( -20 per cent ), Mia ALPHA ( -34 per cent ) and the Apple Watch ( -43 per cent ).
The authors list the devices ’ accuracy for heart rate and energy expenditure in an easy-to-understand table , which can be referenced in Figure 2 ( page 6 ) of the publication .
Conclusions : The authors conclude that all four devices underestimated heart rate ( by between 1 and 9 per cent depending on device ). Additionally , energy expenditure was also underestimated for all devices , but by far greater degrees ( with average device difference ranging from 9 to 43 per cent below the gas analyser results ). These are considered poor estimates of energy expenditure .
Pros : This is a good study using established and reliable methods to compare the watches ’ accuracy with regard to heart rate and energy expenditure . The authors further comment that the accuracy of the devices may be reduced during higher intensity exercise or while completing resistance training due to movement artifact ( error due to movement of the body tissue during measurement ).
Given the devices all underestimated heart rate , caution should be exercised when advising clients who may be at risk during higher intensity exercise to base their heart rate upon these devices . This pertains not only to high intensity exercise , but also to exercise at an upper personal limit for your clients .
Would we buy one of these devices ? Absolutely ; however , the purchase would be based upon our specific information requirements , i . e . the device with the worst accuracy at reporting heart rate would not be a first choice for ‘ at risk ’ clients .
Cons : It would have been interesting if the authors had completed the testing protocol with low intensity exercise , high intensity exercise and when completing resistance training exercises . These paradigms would make for a good follow-up study .
Associate Professor Mike Climstein , PhD FASMF FACSM FAAESS is one of Australia ’ s leading Accredited Exercise Physiologists and researchers . mike . climstein @ sydney . edu . au
Joe Walsh , MSc is a sport and exercise scientist . As well as working for Charles Darwin and Bond Universities , he is a director of Fitness Clinic in Five Dock , Sydney . fitnessclinic . com . au
NETWORK SPRING 2016 | 45