Research article - (2016)15, 540 - 547
Validation of Biofeedback Wearables for Photoplethysmographic Heart Rate Tracking
Edward Jo1,, Kiana Lewis1, Dean Directo1, Michael J. Kim1, Brett A. Dolezal1,2
1Human Performance Research Laboratory, Department of Kinesiology and Health Promotion, California State Polytechnic University Pomona, Pomona, CA, USA
2Exercise Physiology Research Laboratory, David Geffen School of Medicine and Department of Physiology, University of California, Los Angeles, Los Angeles, CA, USA

Edward Jo
✉ Human Performance Research Laboratory, Department of Kinesiology and Health Promotion, California State Polytechnic University Pomona, Pomona, CA, USA
Email: ejo@cpp.edu
Received: 17-06-2016 -- Accepted: 27-07-2016
Published (online): 05-08-2016
ABSTRACT

The purpose of this study was to examine the validity of HR measurements by two commercial-use activity trackers in comparison to ECG. Twenty-four healthy participants underwent the same 77-minute protocol during a single visit. Each participant completed an initial rest period of 15 minutes followed by 5 minute periods of each of the following activities: 60W and 120W cycling, walking, jogging, running, resisted arm raises, resisted lunges, and isometric plank. In between each exercise task was a 5-minute rest period. Each subject wore a Basis Peak (BPk) on one wrist and a Fitbit Charge HR (FB) on the opposite wrist. Criterion measurement of HR was administered by 12-lead ECG. Time synced data from each device and ECG were concurrently and electronically acquired throughout the entire 77-minute protocol. When examining data in aggregate, there was a strong correlation between BPk and ECG for HR (r = 0.92, p < 0.001) with a mean bias of -2.5 bpm (95% LoA 19.3, -24.4). The FB demonstrated a moderately strong correlation with ECG for HR (r = 0.83, p < 0.001) with an average mean bias of -8.8 bpm (95% LoA 24.2, -41.8). During physical efforts eliciting ECG HR > 116 bpm, the BPk demonstrated an r = 0.77 and mean bias = -4.9 bpm (95% LoA 21.3, -31.0) while the FB demonstrated an r = 0.58 and mean bias = -12.7 bpm (95% LoA 28.6, -54.0). The BPk satisfied validity criteria for HR monitors, however showed a marginal decline in accuracy with increasing physical effort (ECG HR > 116 bpm). The FB failed to satisfy validity criteria and demonstrated a substantial decrease in accuracy during higher exercise intensities.
Key words: Photoplethysmography, biosensor, biotechnology, fitness, cardiovascular

Key Points
  • Modern day wearable multi-sensor activity trackers incorporate reflective photoplethymography (PPG) for heart rate detection and monitoring at the dorsal wrist.
  • This study examined the validity of two PPG-based activity trackers, the Basis Peak and Fitbit Charge HR.
  • The Basis Peak performed with accuracy compared with ECG and results substantiate validation of heart rate measurements. There was a slight decrease in performance during higher levels of physical exertion.
  • The Fitbit Charge HR performed with poor accuracy compared with ECG especially during higher physical exertion and specific exercise tasks. The Fitbit Charge HR was not validated for heart rate monitoring, although better accuracy was observed during resting or recovery conditions.








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Validation of Biofeedback Wearables for Photoplethysmographic Heart Rate Tracking
Edward Jo, Kiana Lewis, Dean Directo, Michael J. Kim, Brett A. Dolezal
2016(15), 540 - 547.
DOI: https://doi.org/