Validation and Usability Evaluation of Mobile Application to Monitor Real-Time Exercise Heart Rate Zone

Abstract

A mobile application to monitor heart rate (HR) during an exercise called Chromozone was developed to enable a user to regulate exercise intensity using a color-coded system rather than numerical display in the most conventional device. In this study, the agreement of HR from Chromozone was compared against the HR dataset from a clinically accepted electrocardiogram (ECG) on different exercise intensity and to assess its reliability by intra-day repeated assessments. Additionally, the usability aspect of the Chromozone smartphone application was also assessed. Forty-two participants underwent self-selected exercise intensities (based on individual HR reserve) included for 5-min followed by a cool-down period (3-min). A 20-min rest period was given to the participant before repeating the same exercise protocol two more times. Chromozone was found to generate excellent criterion-concurrent validity (r = 0.998, p < 0.001) and acceptable bias of 1.96 bpm (Limits of Agreement; LoA: 3.07 to -3.51) for relative and absolute agreement, respectively. Similarly, relative (intraclass correlation coefficient test: 0.998, p < 0.001) and absolute (within-subject coefficient of variation: 1.95 ± 1.4%) reliability using Chromozone application shows an excellent consistency. Additionally, this study also showed that the usability level of the Chromozone application is beyond the satisfactory level. The outcome of this work provides strong support for Chromozone application as a valid and reliable exercise HR monitoring tool that could potentially help athletes, active individuals as well as the clinical population to monitor and regulate their exercise training regime more effectively.