Psychometric Parameters of Zephyr Bioharness & Fitbit Charge

Abstract

Technological innovations have lead to the development of Wearable Physiological Monitoring devices, that have enabled researchers and clinicians in real-time monitoring of physiologic function within a field setting. However, it is important to establish the psychometric properties of a device prior to its utilization. A systematic review was conducted to provide a summary and appraise the quality of the literature on psychometric parameters of Zephyr Bioharness and Fitbit devices. Based on this review, we addressed the current gaps in the literature regarding the reliability parameters of Zephyr Bioharness and Fitbit Charge devices, and established the validity and agreement properties of Fitbit Charge device. For our systematic review, we searched the Google Scholar and PubMed databases to identify articles. To establish the reliability, validity and agreement parameters of Zephyr Bioharness and Fitbit Charge devices, a convenience and snowball sampling approaches were used to recruit sixty participants (30 females) from university student, staff, faculty population, and MacSeniors Community Program at McMaster University. The performance of Zephyr and Fitbit devices were assessed throughout three phases; rest, Modified Canadian Aerobic Fitness Test and recovery. In our study, at rest, inter-session average heart rate (beats/min.) ICCs (SEM) for Zephyr and Fitbit ranged from 0.90 – 0.94 (1.73 – 2.37) and 0.88 – 0.94 (1.83 – 2.67) respectively. At mCAFT, the Zephyr ICCs (SEM) ranged from 0.91 – 0.97 (3.12 – 4.64) and 0.85 – 0.98 (3.28 – 4.88) for the Fitbit. Throughout the recovery, the ICCs (SEM) ranged from 0.93 – 0.97 (2.65 – 4.66) and 0.76 – 0.91 (3.17 – 4.67) for Zephyr and Fitbit devices respectively. Pearson’s correlation coefficients and (Mean differences) for heart rate variable were 0.97 – 0.99 (-0.60 – 0.02) at Rest, 0.89 – 0.99 (13.51 – 0.62) at submaximal testing and 0.70 – 0.84 (-0.54 – 2.52) throughout recovery. The average agreement bias of heart rate in pair-wise device comparison indicated mean differences of -0.20, 4.00 and 1.00 at rest, sub-maximal testing and recovery respectively. We identified fair to very good quality evidence from 14 studies. The Zephyr Bioharness and Fitbit Charge devices demonstrated excellent reliability measures, and the Fitbit Charge device heart rate variable demonstrated strong to very strong correlations when concurrently compared with Zephyr, and provided valuable information regarding its interchangeable use in a sample of sixty healthy male and female participants of various age groups during a resting, standardized submaximal fitness and recovery phases.