Reliability and validity of a smartphone pulse rate application for the assessment of resting and elevated pulse rate

Purpose/hypothesis: This study was designed to investigate the test-retest reliability, concurrent validity, and the standard error of measurement (SEm) of a pulse rate assessment application (Azumio®'s Instant Heart Rate) on both Android® and iOS® (iphone operating system) smartphones as compared to a FT7 Polar® Heart Rate monitor. Number of subjects: 111.

Resting (sitting) pulse rate was assessed twice and then the participants were asked to complete a 1-min standing step test and then immediately re-assessed. The smartphone assessors were blinded to their measurements.

Test-retest reliability (intraclass correlation coefficient [ICC 2,1] and 95% confidence interval) for the three tools at rest (time 1/time 2): iOS® (0.76 [0.67-0.83]); Polar® (0.84 [0.78-0.89]); and Android® (0.82 [0.75-0.88]). Concurrent validity at rest time 2 (ICC 2,1) with the Polar® device: IOS® (0.92 [0.88-0.94]) and Android® (0.95 [0.92-0.96]). Concurrent validity post-exercise (time 3) (ICC) with the Polar® device: iOS® (0.90 [0.86-0.93]) and Android® (0.94 [0.91-0.96]). The SEm values for the three devices at rest: iOS® (5.77 beats per minute [BPM]), Polar® (4.56 BPM) and Android® (4.96 BPM).

The Android®, iOS®, and Polar® devices showed acceptable test-retest reliability at rest and post-exercise. Both the smartphone platforms demonstrated concurrent validity with the Polar® at rest and post-exercise.

The Azumio® Instant Heart Rate application when used by either platform appears to be a reliable and valid tool to assess pulse rate in healthy individuals.