Blog post by Marco Altini.
In this post I cover best practices and provide some additional guidelines around the camera-based measurement in HRV4Training. In the second part of this post, we provide general guidelines that apply regardless of your measurement setup.
HRV4Training's unique camera based measurement was clinically validated and showed to be equivalent to chest strap measurements (Polar H7) as well as electrocardiography (find out more here). Our validation was on iPhones, and while we ported the same algorithms on Android, and validated them with respect to chest straps, fragmentation might cause issues. We cannot test all devices and guarantee accuracy on the different Android phones, cameras and operating system versions. However, we developed methods to detect possible issues with your specific setup and inform you, so that you can take action. Please read below for some additional information regarding measuring with the camera on Android and check out this post for our validation on Android.
Make sure to follow these guidelines for all your measurements:
As first time users, try to take 2-3 measurements following the advice above, and you should be able to acquire high quality data rather easily. Try to make sure the data quality is labeled as "optimal" by the app, and repeat the measurement otherwise. If you experience additional issues, feel free to contact us. You can try the camera measurement anytime from Menu / Resources / Camera measurement practice mode.
The app provides the following signal quality categories:
Additional notes on Android measurements
First of all, make sure that HRV4Training is allowed to access your camera. Android apps need permission to access the camera, you can enable the app from Settings / Apps / HRV4Training, Permissions, as shown below:
As mentioned above, our validation was on iPhones, and while we ported the same algorithms on Android and validated them with respect to chest straps, fragmentation might cause issues. We cannot test all devices and guarantee accuracy on the different Android phones, cameras and operating system versions. However, we tried to develop methods to detect possible issues with your specific setup and inform you, so that you can take action.
In particular, during the Practice mode as well as during each measurement, we check that the camera is providing frames at the required frequency and with very limited variations, which is key to provide accurate data. If your phone is unable to sustain the required frequency or lags some frames, we can detect it and inform you, as shown below.
Sometimes terminating other apps or making sure that there are no other time consuming processes going on in the background can be sufficient to obtain a good reading. You can also try to force stop HRV4Training and launch it again. However, if the problem keeps showing up at each measurement, it could be that simply your setup does not work with this sensor modality. In this case, we recommend using a Bluetooth SMART sensor, for example a Polar H7. If you do not plan to use HRV4Training using a chest strap, you can always get refund on the Google Play Store.
General guidelines (camera or chest strap)
Here are a few other points that are relevant regardless of the sensor modality you use (camera or Bluetooth low energy sensor):
If you like the app and or the blog, take a minute to review HRV4Training on the Apple store.
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Especially for the ones that are not much into Twitter, feel free to use the Facebook HRV4Training page as a place to open discussions around HRV, training, performance and more.
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1. Context & Time of the Day
3. Paced breathing
4. Orthostatic Test
5. Slides HRV overview
6. rMSSD vs SDNN
1a. Acute Changes in HRV
1b. Acute Changes in HRV (population level)
1c. Acute Changes in HRV & measurement consistency
1d. Acute Changes in HRV in endurance and power sports
2a. Interpreting HRV Trends
2b. HRV Baseline Trends & CV
3. Tags & Correlations
4. Ectopic beats & motion artifacts
5. HRV4Training Insights
6. HRV4Training & Sports Science
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10. Repeated HRV measurements
11. VO2max and performance
12. HR, HRV and performance
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14. Publication: VO2max & running performance
15. Estimating running performance
Camera & Sensors
1. ECG vs Polar & Mio Alpha
2a. Camera vs Polar
2b. Camera vs Polar iOS10
2c. iPhone 7+ vs Polar
2d. Comparison of PPG sensors
3. Camera measurement guidelines
4. Validation paper
5. Android camera vs Chest strap
6. Zoom HRV vs Polar
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8. Scosche Rhythm24
9. Apple Watch
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4. Sleep tracking
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6a. Integration with Strava
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7. HRV4T Coach advanced view
8. Acute HRV changes by sport
9. Remote tags in HRV4T Coach
10. VO2max Estimation
11. Acute stressors analysis
12. Training Polarization
13. Custom desirable range / SWC
14. Lactate Threshold Estimation
15. Functional Threshold Power(FTP) Estimation for cyclists
16. Aerobic Endurance analysis
1. Intro to HRV
2. HRV normal values
3. HRV by sport
4. HRV, strength & power
5. AngelSensor & HRV
6. HRV 101: How to
7. Top 5 most read articles
8. HRV normalization by HR
9. How to use HRV, the basics