Validity Of The DiagnostixTM 2100 And Fitbit Charge HRTM In Assessing Heart Rate

Abstract

The importance of exercise intensity is an important factor when maximizing the health benefits that result from exercise. New innovations in consumer based activity trackers and electronic healthcare monitoring devices have been able to quantify the level of exercise intensity based on heart rate (HR) values. However, there is limited research assessing the validity of these devices. PURPOSE: To assess the validity of the Fitbit Charge HR (FB) and ACSC Diagnostix 2100 Fingertip Pulse Oximeter (PO) in assessing heart rate during exercise in comparison to the heart rate from an electrocardiogram (EKG). METHODS: Healthy college students (n=30, 18 females) performed 1 min of standing rest, 10 min of the standard Bruce Protocol test on a treadmill, and a 2 min cool-down walk. Each participant simultaneously wore the FB on the right wrist, the PO on the right index finger, and had 10 electrodes placed on their chest for the 12-lead EKG. HR was recorded from each device every minute. Absolute differences between the 3 HR monitors were compared using repeated measures ANOVA. Pearson r correlation coefficients and Standard Error of Estimate (SEE) were calculated to determine the relationships between each HR monitor vs. EKG. RESULTS: Repeated measures ANOVA indicated a significant difference in HR between the 3 monitors, F(2,58)=16.876, p<0.001. Post hoc tests indicated a significant difference between EKG and FB (132.1 ± 13 vs. 120.5 ± 13.7 bpm, p<0.001), and EKG and PO (132.1 ± 13 vs. 121.9 ± 15.5 bpm, p<0.001). The correlation between the EKG and FB was r=0.64, p<0.001, SEE 10.2 bpm, whereas the correlation between EKG and PO was r=0.63, p<0.001, SEE 10.27 bpm. CONCLUSIONS: Large absolute differences and modest correlation values do not indicate a strong agreement between the FB or PO vs. EKG. Therefore, the extent of each device’s validity to monitor HR is questionable when compared to the gold standard EKG.