HRV4Training on Android

HRV4Training launched on Android, on March 23rd, you can find it on Google Play. The app contains all features present on iPhone, from the camera based measurement to all the insights we built on top of daily measurements, annotations and workouts as well as integrations with other apps like SportTracks, Strava and TrainingPeaks. In this post, we go over the  main features in the app and provide an overview of most functionalities and insights. In particular, we'll look at:

• Data acquisition
  • ​Camera
  • Bluetooth SMART
  • ANT+
• Daily advice, tags, history and baseline
• Insights:
  • acute changes in response to different stressors (training, alcohol, travel, menstruation, etc.)
  • long term trends (heart rate, HRV, coefficient of variation, automatic long term trend detection, etc.)
  • VO2max estimation (runners and cyclists)
  • Weekly and monthly summaries of your stats
  • Population comparisons
  • Training polarization analysis
  • Training load analysis & injury risk
• Data integrations:
  • SportTracks
  • Strava
  • TrainingPeaks
• HRV4Training Coach

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For a general overview of HRV and HRV4Training, please check the quickstart guide.

Data acquisition

​HRV4Training on Android provides three options in terms of data acquisition:

• Camera-based
• Bluetooth SMART
• ANT+ (internal radio or adapter)

As several Android phones include ANT+ radios, and can therefore talk to your Garmin chest strap, we added support for these sensors, which is not present on HRV4Training on iPhones, as adapters that we currently do not support are needed. Regular bluetooth smart sensors (e.g. a Polar H7) will also work. Please read below for additional details on ANT+.

We also implemented our unique camera based measurement, that should be supported by most recent phones. You will be able to try this modality anytime from the Resources menu, and practice also the first time you use the app. We also check that your hardware supports this sensor modality, and inform you. For a validation please check this blog post as well as guidelines at this link.

If you use ANT+, make sure to have the following apps installed in your phone: ANT Radio Service, ANT+ Plugins Service, ANT USB Service. You might also need to try first the ANT Demo app, especially if you have a USB adapter, then remember to connect your sensor to HRV4Training from Settings, Scan.

Daily advice, tags, history and baseline

Once you picked a sensing modality to acquire your HRV measurement, the best way to use the app is to measure each morning as soon as you wake up. Try to stick to a morning routine, for example measuring in the same body position, more or less at the same time, and while relaxing, before other stressors start affecting you (e.g. eating, drinking, physical activity, mental stress, etc.). By measuring under these conditions, we can better capture overall physiological stress from previous days (and workouts) and provide meaningful advice and insights.

Your morning HRV value will contribute to your baseline (7 days moving average) and normal values (30 days desirable range - see below). After each measurement you will be prompted with a short questionnaire that will help contextualize your measurements and make sense of your data, we call these entries Tags. Try to be consistent and follow the same monitoring routine. If you do get out of bed before taking your test, make sure you are again well rested (e.g. relax for a minute).

Daily advice

Changes in HRV on consecutive days and with respect to your baseline and desirable range will be analyzed to determine possible periods of higher physiological stress. The daily advice can be used to understand under how much stress your body is, and make daily adjustments to your trainings accordingly.

​HRV4Training provides advice based on objective assessment of physical condition and your subjective scores. HRV over the last week is used to determine your baseline (at least 4 days of measurements are required), while the past 30 days of data are used to determine what your normal HRV values are, basically what variations are just normal day to day changes and what variations are more meaningful.

The daily advice aims at helping you in making small daily adjustments to your training program, by keeping in consideration not only how your score changed from yesterday's (acute change), but also with respect to your past 30 days variations (desirable range or normal values), and factoring in your subjective scores (muscle soreness, motivation to train, perceived performance and sleep quality) and recent trends (when enough data is present). Check out this post for more information on the daily advice.

Morning tags

Context is everything. After each measurement you'll be prompted with different Tags related to your current lifestyle and trainings. You can annotate not only training days and intensities but also a series of other parameter that can affect physiological stress, performance, and training, for example sleep quality, mental tiredness, muscle fatigue and so on. 

Your annotated Tags will be used to provide analytics and interpret physiological data, for example analyze the effect of acute stressors (day to day variations in response to events such as intense training, alcohol intake, travel, etc.) as well as to provide context to better understand the big picture. Please read below for more details on HRV4Training's insights.

​You'll also be able to see some of the tags in the history view and plot custom correlations.  Finally, you can even add up to three custom tags.

​If you are a Strava or TrainingPeaks user, you can also link Strava or TrainingPeaks and HRV4Training and get your training-related tags automatically in the app, so that you can save a bit of time in the morning

History and baseline

​Once you've got some data, use the history tab to browse through it and look at the different features that were extracted during the test. You'll also be able to see the impact of some of your tags (e.g. travel, alcohol intake, injuries, etc.) on your physiological stress level.

The Baseline page helps you in going beyond short daily variability, and get a better overview of your physical condition. The blue line is a 7 days moving average, which captures the global trend of your HRV, without being too affected by daily swings.

Insights

HRV4Training provides several advanced experimental analysis that look at both acute HRV changes and long term trends to better understand the big picture. As you accumulate more data, you'll be able to use it to explore many different aspects. In particular, under Menu - Insights, you can find:

Weekly and monthly summaries

Pick the metric most representative of your athlete's trainings (e.g. RPE, TSS, Suffer Score, training distance) and analyze training load breakdowns by week and month to keep better track of overall progress.

Acute HRV changes in response to training and other stressors

​Systematic analysis of day to day changes in HRV on days following training, alcohol intake, travel, menstruation and sick days. Are your athletes physiologically rested after rest days and easy training? What drop in HRV can you expect after an intense training? How does travel affect their physiology?  

Additional resources:

• Acute changes feature overview
• Acute changes publication (consistent reductions in HRV following more intense trainings)

HRV trends

Provide more insights on the big picture. Look at baseline changes on multiple parameters relevant to your physical condition (e.g. HRV baseline, HRV, coefficient of variation, training load), etc.  The app can automatically determine if your recent HR or HRV trend is changing in a trivial way, or if the change is something to take more seriously, based on your historical data. 

Additional resources:

• HRV Trends analysis literature and feature overview

Correlations

Mainly for exploratory analysis inside the app. Look at what factors are related to physiological changes, and try to adjust your lifestyle accordingly (a good one is typically sleep quality).

Additional resources:

• Correlations feature overview

Training load analysis

You can pick the metric most representative of your trainings (e.g. TSS, Suffer Score, training distance or your own custom metric) and analyze fitness & fatigue, determined as chronic and acute training loads, as well as readiness to perform and injury risk.

Additional resources:

• Training load analysis feature overview
• Injury risk

Training polarization analysis

This analysis allows you to get an overview of how hard you are training and potentially polarize more your training, as a more polarized approach, typically involving training about 80% of the time at very low intensities,  has been shown to improve performance for both recreational and elite athletes. More details on this analysis at this link.

Additional resources:

• Training polarization feature overview
• Case study

VO2max estimation

For runners using the Strava or TrainingPeaks integration and training with a HR monitor, HRV4Training can estimate cardiorespiratory fitness level (VO2max). Check out this post for more details.

Additional resources:

• Algorithms overview here and here
• Publication on the relation between VO2max and running performance

Population comparisons

In this page you can see how you compare with respect to other HRV4T users. You'll be able to pick different physiological parameters (heart rate, rMSSD, Recovery Points) as well as stratify by age and gender. ​You can learn more about HR and HRV population values on this blog post.

Additional resources:

• Feature overview

Data integrations

HRV4Training provides various data integrations that are used either to make your life easier when you fill in the morning tags, as many metrics related to training can be pre-compiled automatically, or to build additional insights, such as training load analysis, VO2max estimation, training polarization, and so on. You can also browse your trainings summaries by tapping the icons in the History page. The main integration we provide at this stage are with SportTracks, Strava and TrainingPeaks. HRV4Training can also push different parameters to SportTracks and TrainingPeaks, in case you'd like to analyze your physiological data in these platforms. See some screenshots below.

HRV4Training Coach

HRV4Training on Android is fully compatible with HRV4Training Coach, your athletes/clients can be on either of the two platform and data will be retrieved and displayed in the same way on HRV4Training Coach. For an overview of the coach platform, please check out this link. The Coach platform will keep being available on iOS devices only for now.

That's all for our brief overview of the upcoming Android app. Make sure to check out the Blog for more details on the different functionalities and data analytics.

We hope you'll enjoy the app and that it will be useful in helping you making sense of physiological data.