Introduction

Multi HR is an application designed for simultaneously monitoring and recording data from multiple Bluetooth heart rate devices. It features real-time data visualization, data export capabilities, and professional statistical analysis tools, making it particularly suitable for sports science research applications.

Disclaimer: This application is not intended for medical diagnosis but for digital evaluation and scientific research purposes only.

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Key Features

  • Simultaneous multi-device connection and monitoring
  • Real-time heart rate data visualization
  • Data recording and export (Excel/CSV)
  • Professional statistical analysis (Pearson correlation coefficient, Bland-Altman analysis)
  • Support for mainstream BLE heart rate devices with 0x180D service (Tested with Polar H10, Polar Sense, BigRun Team, HR01, Garmin 965 heart rate broadcast. Note: Apple Watch is not supported as it doesn’t use the 0x180D service)

User Guide

Device Connection

  • Launch the app and tap the search icon in the top right to scan for devices
  • Locate your heart rate device in the available devices list
  • Tap “Connect” to establish connection
  • Connected devices will appear in the “Connected Devices” list

Data Recording

  • Tap the record button (red dot icon) in the top right to start recording
  • View real-time heart rate graphs during recording
  • Tap the record button again to stop recording
  • Choose how to process the data:
    • Export as Excel
    • Export as CSV
    • Analyze data
    • Discard data

Data Analysis

The app assumes you’re using multiple heart rate devices, with one serving as a reference device and others as test devices. For example, using a Polar H10 as reference and an HR armband as test device.

The analysis page offers two main statistical methods:

Pearson Correlation Coefficient Analysis

  • The Pearson correlation coefficient evaluates the linear correlation between two devices’ measurements:
    • Range: -1 to 1
    • 1: Perfect positive correlation
    • -1: Perfect negative correlation
    • 0: No linear correlation
    • Interpretation standards:
      • r ≥ 0.8: Strong correlation
      • 0.5 �� r < 0.8: Moderate correlation
      • r < 0.5: Weak correlation

Bland-Altman Analysis

  • Bland-Altman plots are essential tools for assessing agreement between two measurement methods:
    • X-axis: Mean of measurements from both methods
    • Y-axis: Difference between measurements
    • Center line: Mean difference
    • Upper/lower limits: 95% limits of agreement (±1.96SD)
    • Key interpretation points:
      • Random distribution of differences around zero
      • Presence of systematic bias (center line proximity to zero)
      • 95% of points within agreement limits
      • Relationship between differences and measurement magnitude

Data Export

Two export formats are supported:

  • Excel format (.xlsx)
    • Includes detailed timestamps
    • Multi-device data in separate columns
  • CSV format
    • Universal format for easy import into other analysis software
    • Contains basic time and heart rate data

Important Notes

  • Before use, ensure:
    • Devices are fully charged
    • Bluetooth is enabled
    • Heart rate devices are properly worn
  • During recording:
    • Keep devices within range
    • Maintain stable Bluetooth connection
    • Avoid backgrounding the app despite background permissions
  • When analyzing data:
    • Ensure sufficient data quantity (recommend >5 minutes)
    • Identify outliers
    • Interpret results in context