title: How accurate are the wrist-based heart rate monitors during walking and running activities? Are they accurate enough?
abstract: BACKGROUND
  Heart rate (HR) monitors are valuable devices for fitness-orientated individuals. There has been a vast influx of optical sensing blood flow monitors claiming to provide accurate HR during physical activities. These monitors are worn on the arm and wrist to detect HR with photoplethysmography (PPG) techniques. Little is known about the validity of these wearable activity trackers.
  
  
  OBJECTIVE
  Validate the Scosche Rhythm (SR), Mio Alpha (MA), Fitbit Charge HR (FH), Basis Peak (BP), Microsoft Band (MB), and TomTom Runner Cardio (TT) wireless HR monitors.
  
  
  METHODS
  50 volunteers (males: n=32, age 19-43 years; females: n=18, age 19-38 years) participated. All monitors were worn simultaneously in a randomised configuration. The Polar RS400 HR chest strap was the criterion measure. A treadmill protocol of one 30 min bout of continuous walking and running at 3.2, 4.8, 6.4, 8.0, and 9.6 km/h (5 min at each protocol speed) with HR manually recorded every minute was completed.
  
  
  RESULTS
  For group comparisons, the mean absolute percentage error values were: 3.3%, 3.6%, 4.0%, 4.6%, 4.8% and 6.2% for TT, BP, RH, MA, MB and FH, respectively. Pearson product-moment correlation coefficient (r) was observed: r=0.959 (TT), r=0.956 (MB), r=0.954 (BP), r=0.933 (FH), r=0.930 (RH) and r=0.929 (MA). Results from 95% equivalency testing showed monitors were found to be equivalent to those of the criterion HR (±10% equivalence zone: 98.15-119.96).
  
  
  CONCLUSIONS
  The results demonstrate that the wearable activity trackers provide an accurate measurement of HR during walking and running activities.
authors.affiliation: School of Health, Physical Education and Recreation, University of Nebraska at Omaha , Omaha, Nebraska , USA.
authors.forename: Sarah E
authors.identifier: 0000-0003-0728-7465
authors.initials: SE
authors.lastname: Stahl
authors.affiliation: School of Health, Physical Education and Recreation, University of Nebraska at Omaha , Omaha, Nebraska , USA.
authors.forename: Hyun-Sung
authors.initials: HS
authors.lastname: An
authors.affiliation: School of Health, Physical Education and Recreation, University of Nebraska at Omaha , Omaha, Nebraska , USA.
authors.forename: Danae M
authors.initials: DM
authors.lastname: Dinkel
authors.affiliation: School of Health, Physical Education and Recreation, University of Nebraska at Omaha , Omaha, Nebraska , USA.
authors.forename: John M
authors.initials: JM
authors.lastname: Noble
authors.affiliation: School of Health, Physical Education and Recreation, University of Nebraska at Omaha , Omaha, Nebraska , USA.
authors.forename: Jung-Min
authors.initials: JM
authors.lastname: Lee
keywords: Assessing physiological demands of physical activity; Assessing validity and reliability of test of physiological parameters; Health promotion; Physical activity; Validity