Accuracy and Reliability of Commercial Wrist-Worn Pulse Oximeter During Normobaric Hypoxia Exposure Under Resting Conditions

ABSTRACT

Purpose: The present study analyzed peripheral blood oxygen saturation (S_pO₂) and heart rate (HR) measurements taken on the Garmin fēnix® 5X Plus watch, comparing them to measurements taken on a standard medical-grade pulse oximeter during normobaric hypoxia exposure under resting conditions. Methods: Thirteen women (mean ± SD: Age 20 ± 1 years, height 165 ± 5 cm, mass, 67 ± 9 kg) and ten men (mean ± SD: Age 21 ± 3 years, height 177 ± 6 cm, mass 78 ± 11 kg) sat inside a customized environmental chamber while the fraction of inspired oxygen (F_IO₂) was adjusted to simulate altitudes of 12,000; 10,000; 8,000; 6,000; and 900 ft. The novel commercial device (Garmin fēnix®) and a medical-grade pulse oximeter (Nonin® 7500) were used to measure S_pO₂ and HR in triplicate at each simulated altitude. Bland–Altman analyses were used to assess differences between methods. Results: Bland–Altman analysis indicated 3.3% bias for S_pO₂ measurements taken on the Garmin fēnix® at 12,000 ft of simulated altitude (limits of agreement: −1.9–8.6%). Mean differences in S_pO₂ measurements were smaller at the remaining simulated altitudes, where bias measurements ranged from 0.7% to 0.8%. The Garmin fēnix® also underestimated heart rate, but those discrepancies were minimal (bias measurements at all simulated altitude exposures were < 1.0 bpm). Conclusions: With the exception of readings taken at 12,000 ft of simulated altitude, the Garmin fēnix® exhibits minimal overestimation of S_pO₂ and minimal underestimation of HR during simulated altitude exposure. These data suggest the Garmin fēnix® watch may be a viable method to monitor S_pO₂ and HR under most ambient environmental conditions.

KEYWORDS:

• Altitude
• athletics
• track and field
• wearable technology

Acknowledgments

Support for this work was provided by the Department of Exercise Science within the Congdon School of Health Sciences. We would also like to thank the Department of Physical Therapy (Congdon School of Health Sciences) for the use of shared lab space/equipment and LJK for his lifetime of guidance and support. KRF, RAB, and MRK conceived the study and designed the experiments. CJL was the lead author of the manuscript. She drafted the manuscript, performed statistical analyses, and helped field manuscript revisions. PAR and LAG assisted with experiments and manuscript preparation. MRK oversaw experiments and assisted with statistical analyses. He also converted the manuscript draft to the final version submitted and was responsible for manuscript revisions. All authors read and approved the final manuscript.

Additional information

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. The Garmin fēnix® 5X Plus smartwatch that was examined in the present study was purchased by study investigators (not provided by the smartwatch manufacturer).