Honors College Theses

Publication Date

2026

Major

Rehabilitation Sciences (B.S.)

Release Option

Open Access

Faculty Mentor

Andrew Flatt

Abstract

Purpose: To assess the agreement between the Garmin Forerunner 265 (a commercially available sports watch) and a single-channel electrocardiographic (ECG) chest strap for determining resting heart rate variability (HRV). Secondary aims were to assess the impact of skin tone and body position on measurement accuracy.

Methods: Young adults (n = 30, 57% women) aged 18–39 years without known cardiovascular conditions and without tattooing or scarring on the dorsal left wrist were recruited. HRV was recorded simultaneously using ECG and the Forerunner 265’s optical sensor during Garmin’s 2-minute “Health Snapshot.” Measurements were obtained in three standardized positions: supine, seated, and standing. HRV values automatically generated by the Garmin application were compared with ECG-derived HRV calculated using specialized analysis software. Skin tone was assessed using the Fitzpatrick scale.

Results: Resting heart rate demonstrated no significant bias, excellent relative and absolute agreement, and narrow 95% limits of agreement across all positions. Contrastingly, root-mean square of successive differences and standard deviation of normal RR intervals demonstrated greater error (heteroscedasticity) and underestimation (proportional bias) as values increased, along with poor absolute and relative agreement across all positions, particularly during standing. Skin tone did not appear to influence error, although the sample with darker skin tone was limited.

Conclusions: HRV estimates from the Garmin Forerunner 265 Health Snapshot are unsuitable for research purposes and patient or athlete monitoring based on their poor agreement with ECG.

Download

Share

COinS