Table 3.

Summary table of current investigations determining validity of various wearable technology devices compared to a criterion measure for heart rate.

Reference	Subjects	Activity	Criterion	Validity - Correlation	Validity - % Difference
Gillinov et al. 2017 (9)	N = 50 (27 females, 23 males); 38±12 years	4.5 min at 3 intensities on each piece of equipment: treadmill, cycling, elliptical w/and w/o arms	12-lead ECG	Polar H7 (0.99) > Apple Watch (0.92) > TomTom Spark (0.83) > Garmin 235 (0.81) > Scosche Rhythm (0.75) > Fitbit Blaze (0.75)	MAPE reported for each specific exercise, but the order typically was Polar < Apple Watch < TomTom Spark < Scosche Rhythm < Garmin 235 < Fitbit Blaze
Wallen et al. 2016 (16)	N = 22 (11 females, and 11 males), 24.9±5.6 years	1-hr involving rest, treadmill walking and running, and cycling	3-lead ECG	Apple Watch (0.98) > Mio Alpha (0.91) > Samsung Gear (0.80) > Fitbit Charge HR (0.78)	% Difference: Apple Watch (−1.3±4.4) < Mio Alpha (−4.3±7.2) < Samsung Gear (− 7.1±10.3) < Fitbit Charge HR (−9.3±8.5)
Jo et al. 2016 (11)	N = 24 (12 females, 12 males), 24.8±2.1 years	77-min protocol involving rest, treadmill walking and running, cycling at 2 different intensities, and strength training	12-lead ECG	Basis Pak (.92) > Fitbit Charge HR (.83)	MAPE: Basis Peak (5.3±8.3) < Fitbit Charge HR (9.8±14.0)