Criterion validity and accuracy of a heart rate monitor

Purpose Heart rate (HR) monitors have recently started to use photoplethysmography, a technique which measures the light reflected by blood vessels and does not require the use of a chest strap. The aim of this study was to test the validity and accuracy of the Garmin® HR monitor, which measures HR at rest and during exercise utilizing the method of photoplethysmography. Methods The sample consisted of 28 males aged 18–32 years. Anthropometric measurements were collected and HR was concomitantly monitored with electrocardiography and with the Garmin® 735XT® device in 2 situations: at rest and during self-selected exercise. Descriptive statistics, linear regression, Bland-Altman plot, mean absolute error (MAE), and mean absolute percentage error (MAPE) were calculated for statistical analysis. Correlations between the HR measurement with electrocardiography and the Garmin® monitor at rest and during exercise were obtained (r = 0.93 and r = 0.96, respectively). Results The difference between Garmin® and electrocardiography HR values showed an error of –1.2 ± 3.3 bpm (rest), while the average error was positive at 0.7 ± 5.1 bpm. MAE and MAPE at rest equalled 2.2 ± 2.8 bpm and 3.3%, respectively. In addition, MAE and MAPE for exercise were 3.5 ± 3.8 bpm and 3.0%, respectively. Conclusions The Garmin Forerunner 735XT can be used at rest, as well as with walking and running activities of light, moderate, and vigorous intensities.