CardioMood Blog

[cardiomood]

RR-intervals import feature

Hello dear CardioMood users!

Today we are proud to introduce you a small but very useful feature - import of rr-intervals. If you have any records that you’ve made not with CardioMood apps you can easily import them!

Please check out the video instruction below.

Thank you!

Your CardioMood Team.

[cardiomood]

Introducing CardioMood Dashboard 2.0

We are proud to announce you CardioMood Dashboard 2.0. Over past months we were preparing huge update of our web-platform. Firstly, we merged our two websites (home.cardiomood.com and doctor.cardiomood.com) to one - app.cardiomood.com 

A lot of features was added to doctor dashboard. 

1) Updated patients or trainees management features.

2) Tools for group analysis. You can now:

see on one graph heart rate and stress level of your trainees or patients

create event labels (black vertical lines on the screenshot) during the group activity

3) Real-time group monitoring

This feature was requested by o lot of our users (doctors, fitness-coaches, trainers, etc.). Now you can observe what’s happening to your trainees or patients in real-time.

Thank you for using CardioMood!

[cardiomood]

Methods of HRV analysis

There are some ways to assess HRV. It can be described using time-domain methods (statistical and geometrical methods) and frequency-domain methods. Time domain methods answer the question: “How big is HRV?”.  Frequency domain methods answers the question: “What is it (HRV) determined by?”.

Statistical methods – indices:

Heart rate (HR), mean RR (mRR) – indices that characterize the heart rate and mean value of R-R interval. They reflect the level of functioning of CVS.

SDNN – standart deviation of the N-N interval (N-N means “normal-to-normal” R-R interval, when it is assumed normal rhytm which is generated by sinoatrial node (it is manifested by normal P-Q-R-S-T complexes in ECG). It characterizes integral HRV without its division into sympathetic and parasympathetic components.

RMSSD – the square root of mean squared differences of successive NN interval. “HRV-index” = 20*Ln(RMSSD). pNN50% – the part (percent) of successive NN intervals, in which the value of difference exceeds 50 ms. These three indices (RMSSD, HRV and pNN50%) reflect “beat-to-beat” variability, characterizing mainly parasympathetic activity of ANS.

Geometrical methods:

I. Based on histogramm building

There are two approaches concerning the choice of the value of width of histogramm pocket.

The first approach is based on 50 ms width of pocket. Usually calculated indices are:

Mo – mode – the most frequent value of R-R interval (the highest column in the histogramm).

AMo – amplitude of mode - number of R-R intervals included in the pocket corresponding to mode. Usually measured in percents (%).

SI – stress-index (s. index of strain of Roman Bayevskiy). SI = AMo(%) / (2*Mo*Var); [Mo] = s; Var = RRmax – RRmin; [Var] = s.

The higher AMo and SI, the higher is the level of strain of ANS (or, in other words, the higher is the level of stress).

The second approach is based on 1/128 s width of pocket.

Heart rate variability triangular index (HRVTi) – is ratio between N (total count of R-R intervals) and n (number of R-R intervals included in the pocket corresponding to mode). The higher is HRVTi, the higher is HRV, espesially conditioned by parasympathetic regulation.

WN1 – width of histogramm which is taken at the level of 1% of N

WN4 - width of histogramm taken at the level of 4% of N

WN5 - width of histogramm which is cut on the level of 10% of N

II. Scatter–plot

Scatter – plot is the plot based on two axises. The first axis (horizontal) corresponds to current R-R interval (RRi). The second axis corresponds to the next (following) R-R interval (RRi+1). We can assess the shape of cloud, its width (W), length (L), ratio between length and width (L/W). The higher is the square of the cloud, the higher is HRV. The higher is the ratio L/W, the higher is the level of neuro-emotional strain (or stress).

[cardiomood]

CardioMood 2.1.1 released

This is basically a maintenance update, which fixes some bugs found in previosu version (2.1.0).

However, there were some changes:

New Settings parameter was added and allows you to eliminate non-physiological RRs.

Frequency-domain parameters are always shown (however VLF can be inaccurate for short measurements).

If you filtered RR-intervals, they will also be applied in text report.

Now the time displayed in graphs and timestamps in the report are the same. It represents the number of seconds (or milliseconds) since the beginning of measurement. Previously, in time-domain graph the time was calculated as a sum of RR-intervals, that’s why all disconnections and periods with no signal were ommited.

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Cheers,

CardioMood Team

[cardiomood]

A few bugs in the latest release

Thanks to user reports we found a couple of bugs in the latest version (2.1) of our Android apps.

It is hard to reproduce these bugs, but we are aware of them and working on a fix.

Bug #1

Sometimes after failed connection to the sensor, the heart rate monitoring service crashes. After this happened, it is not possible to connect to sensor without restarting the app.

Bug #1

Feedback activity crashes sometimes with NullPointerException, due to empty package name.

This is weird. We are investigating the issue.

We are very sorry for the buggy release. Tomorrow’s update will fix it.

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Cheers,

CardioMood Team

[cardiomood]

CardioMood 2.1 is out

We have finally finished our first development iteration of CardioMood framework and published an update for our apps.

This new update incorporates the following changes:

We changed synchronisation process so that you can be aware of its progress

Minimum measurement duration was lowered to 50 RR-intervals

In Expert version, we fixed the rolling window size to 50 RR-intervals for most of parameters

To keep you informed about the updates, we added “News” tab.

We disabled exporting raw data in HRV Lite. Oups! :)

The update also fixes a couple of bugs. If you want to know specific details, please continue reading.

"News" tab added

We thought that it’s important to keep you informed of what’s going on in our project. Since version 2.1 our android apps have the “News” tab.

This is basically an embedded web-browser which shows this blog. All internal links will open within this browser, while links leading to external resources will be handled by the Android system. You can go back by clicking “Back” button of your phone. To refresh the page, you can use a button on the menu.

Right now you cannot disable this tab, but we promise to add a configuration parameter.

50 RR-intervals as a minimal duration

There are plenty of apps that calculate your HRV. Even though they use the same parameter as HRV = 20lnRMSSD, the duration of the recording varies from app to app.

Elite HRV takes 2.5 min recording. Famous ithlete has a 55 seconds duration limit. Setting a limit by time may result in significant difference in RR-intervals count – different measurement will contain different numbers of intervals. As all time-domain metrics (including our favourite HRV) are basically statistical parameters, they are comparable only when the sample size is the same, i.e. the measurements have equal number of RR-intervals.

The duration limit should be chosen based on the purpose of the measurement. For checking your stress level we recommend 2-min duration limit. To estimate HRV it makes more sense to set interval-count limit (100 or maybe 50 RR-intervals).

Changes is parameter calculation

HRV parameter shown in “History” tab was updated. Now it is calculated as an average of 20lnRMSSD for a rolling window, with size being 50 RR-intervals and step 5 RR-intervals. For a trained individual with resting heart rate around 40 – 60, the window will be about 1 minute. We are still experimenting with the parameters, but for now we think 50 RR-intervals will be enough for HRV.

In HRV Expert, we’ve also changed some graphs:

pNN50, 20 ln RMSSD (HRV) graphs were added. 

They use the same window size – 50 NN intervals.

Time-domain, frequency-domain and histogram parameters are still calculated using all data.

Two parameters use individual window sizes:

Stress index is calculated using 2-min rolling window (the average is shown under “Histogram” tab)

Gorgo “A” Index is calculated using 100-interval rolling window (the average is shown under “Histogram” tab)

Emphasizing again: all basic parameters in the report (except Stress Index and Gorgo Index) are calculated over all recorded data.

Data synchronisation

Unfortunately, synchronisation is still not cancellable and blocks the UI… The good news is that now it shows its current progress. This is another step towards a silent background synchronization. We will eventually do this. Promise. :)

There is one more interesting thing to mention. If you have multiple devices or use both HRV Lite and HRV Expert apps, now when performing synchronisation, the app will only download the list of new measurements skipping the data. The data for each new measurement will be downloaded from the server when you first time open it (“lazy” download).

If you have many measurements and reinstalled the app or logged in from a different device, the synchronisation will take several seconds. If you want to see the report, the app will automatically check the presence of data and download it (the Internet will be required) if necessary.

If you have more questions or suggestions, please contact us via [email protected] or just use a Feedback form in the app. And don’t forget to rate our app in Google Play!

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Cheers,

CardioMood Team

[cardiomood]

CardioMood is finishing its migration to new servers

CardioMood started with Heart Rate and Stress Monitor – a small Android app that allowed their users check their stress level in real-time. It was first released more than a year ago and now reaching 10,000 downloads. Unfortunately the uninstall rate was extremely high.

We received a lot of feedback from our users and decided to redesign the platform. Both website and app were refined. On January, 1 we published a paid app CardioMood HRV Expert 2.0 followed by HRV Lite – its free brother.  The old app, however, hasn't been updated yet.

Both of our new apps have been well accepted by users. In fact, we are now receiving emails almost every day! We were surprised by this increase in people's interest and now we realised what the audience wants. But before we can continue with bringing new features we have to update the old app.

Upgrading old CardioMood

The upgrade to version 2.0 consists of 2 stages:

Migration of user data to new server.

Upgrade of the Android app.

We are proud to announce that all user data were successfully migrated to our new server. On the website home.cardiomood.com you can see all your recordings made with the old app. To login you should use the same email and password.

If you have a lot of data, synchronization process can take a while. Please, be patient – this is a one-time procedure.

Old app will be upgraded soon.

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Cheers,

CardioMood Team

[cardiomood]

CardioMood HRV 2.0.5

Dear users,

Both our apps HRV Lite and HRV Expert have recently been updated to version 2.0.5.

This update brings you the following new features:

1. We added new metrics in the report: 

HRV = 20*ln RMSSD – widely used in other apps, such as ithlete or Bioforce HRV 

Poincare plot parameters SD1, SD2 and SD1/SD2

2. History tab was updated. You can now see your HRV score as well as average Stress Index without having to open the recording.

3. The smallest duration limit was lowered to 60 seconds. However we still recommend to use 2-min limit.

The app core was revised and refined. We fixed a couple of bugs and made the app more stable.

When you open recordings that are longer than 5 hours (25 000 RR-intervals), we disable some graphs to ensure stability of the app and avoid ANR.

Hopefully you will appreciate our work by leaving a positive review on Google Play.

Details of the update

History tab now allows you to estimate trends in your stress and HRV.

Stress Index shows averaged value of estimated physical or emotional stress. 2-min rolling window is used for the calculation. Values within the range 40 – 150 are considered normal and shown with green circle. Amber color represents elevated stress level (values in range 150 – 180). When stress index is 180 or higher the circle is red.

When doing intense exercising do not be afraid to see values as high as 1000. This is absolutely normal and shouldn't cause any concerns. However, a constantly high stress index without any apparent reason is abnormal and should be taken as a good sign to visit a doctor.

HRV score is a popular metric used in many apps. It is just a logarithmic scale of RMSSD parameter. HRV of short recordings are often interpreted as a quality of recovery or readiness of your body to training or everyday work.

Higher HRV score is a sign of good health and sufficient recovery. Lower HRV can represent overtraining or incomplete recovery.

Make measurements regularly. Watch your HRV trends and stay healthy!

Screenshots

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Cheers,

CardioMood Team

[cardiomood]

Check your heart rate with your web camera!

Dear users,

we are proud to announce that we added really cool feature for checking out your heart rate by visiting website  http://heartrate.cardiomood.com

The idea of this technology is that the our web cam is able to capture not visible for our eyes blood pulsations of our forehead. 

Webcam 30 times a second makes snapshots of your face, then it calculates the intensity of green component of forehead pixels.

The final step is to calculate the frequency of blood pulsation. So the easiest way is to use Fourier Transform of the intensity signal. 

In 30 seconds you can find out what is your hear rate! It's really very simple! 

Cheers,

CardioMood Team.

[cardiomood]

CardioMood introduces Facebook login

Users hate forms. Registration and login forms only repel the audience! We've received a number of complaints from our users, because our app requires them to specify their email and password in order to create account.

Do we have to make people suffer and waste their time on typing their emails and generating secure passwords? Actually no. We can authenticate the user with just one click!

Our new release of the app now allows you to login via Facebook account. Now you only need one click to join CardioMood!

After you sign up via your Facebook, the system will create a CardioMood profile using your public email.

If you want to use standard login method (email and password), you should update your password using "Change password" feature of the app.

Facebook login is also available on the website: home.cardiomood.com

By the way, whole bunch of new features is coming soon. Stay tuned!

Cheers,

CardioMood Team

[cardiomood]

Introduction to HRV: Physiological principles

In our previous post we explained some basic concepts of heart rate variability and showed how you can use our Android app to measure your stress level. Here, we would like to explain physiological principles of HRV.

What is HRV?

Heart rate variability (HRV) is an express method to assess the functional state of cardiovascular system (CVS) and autonomic nervous system (ANS) by analysis of syncs rhythm.

History

Method of mathematic analysis of HRV has been widely used to assess cosmonauts' functional state since 1961, when Yuriy Gagarin made the first cosmic orbital flight. The HRV was the only way to real-time monitor rapidly changing state of cosmonaut's CVS and ANS, reflecting general state of the organism.

Principle of the method

CVS transports oxygen and nutrients to every cell of the body. That is why it is the main energy supplying system in organism. Thus, fluctuations of CVS activity reflect the need in oxygen and nutrients in organs and tissues.

ANS regulates the metabolism's focus towards the prevalence of trophic or energetic processes in organs and tissues. As a matter of fact, the functioning of each organ and each cell of the body is dependent on phylogenetically formed and genetically defined biorhythms. Every day, each system of organs, each organ, each cell cyclically passes through phases of minimum and maximum of their functional activity. The rule and the necessary condition of normal functioning of organ (or the whole human body) is alternation of energy-consuming period of maximum activity with a recovery period. CVS and ANS play a great role in keeping tissue metabolism at required level according to the demands of organs and their systems as well as during adaptation of organism to changing conditions, such as fulfilment of different occupational tasks or everyday activities.

The hierarchical structure of heart rhythm control

Sinoatrial node is the normal pacemaker of the heart. It has multilevel autonomic and humoral regulation. There are three levels of regulation.

The first level (autonomic level) includes nucleus of the vagus nerve and the respiratory center of medulla oblongata. It works rapidly with low latency (reaction goes very fast) – about 2.5 – 6 sec (High Frequency domain – HF). So, HF domain characterizes basically parasympathetic regulation.

The second level (baroreflex level) includes vasomotor center of the medulla oblongata. It has mixed nature – predominantly sympathetic and to a lesser extent parasympathetic. Its reaction time is about 6 – 25 sec (Low Frequency domain – LF). So, LF domain reflects adaptive vasomotor reactions.

The third level (sympathetic ergotropic and humoral level) consists of subcortical sympathetic ergotropic nerve ganglia. It reflects slow humoral and temperature regulation as well as transitory processes associated with changes in body position (vertical – horizontal). Its reaction time is about 25 – 300 sec (Very Low Frequency domain - VLF).

Our body works according to the following rules:

Normally, when the workload or everyday activity demands do not exceed the capacity of CVS (e.g. rest or light intensity work), the heart is regulated predominantly by autonomic level.

When the workload becomes higher, the organism starts to involve baroreflex level of regulation.

When the workload becomes too high or external conditions become too severe, the organism starts to involve sympathetic ergotropic and humoral level.

So, the higher intensity of work or adaptation, the higher level of regulation is involved.

Each higher level of regulation inhibits activity of lower levels.

The state of stress is characterized by increased heart rate (HR), increased sympathetic tone of ANS, increased blood pressure. State of relaxation is characterized by decrease of HR, increase of parasympathetic tone (synonym – vagal tone) of ANS.

Heart rate variability analysis methods will be described in our future posts.

[cardiomood]

How to check stress level with CardioMood

Our heart is a wonderful organ. It can contract on its own without any outside input. However, without control from the central nervous system, we cannot adapt to changes in our body and our daily activities.

Autonomic control

An autonomic (or vegetative) nervous system that is in charge of our heart consists of two components: sympathetic and parasympathetic nervous systems. The sympathetic nervous system is responsible for our fight-or-flight response. It's activity prepares our body (including our heart) to the challenges we face during the day. As opposed to sympathetic nervous system, parasympathetic is our recovery system. It is responsible for rest and feeding.

There should always be a balance between the two. To make it more clear for you, consider the following analogy.  Sympathetic and parasympathetic nervous systems are like gas and breaks of a car. In order for it to move without damaging the engine they must work together. Our heart is the engine.

Stress level and HRV

In order to maintain our daily activities, the heart always receives stimulation from both of the systems. They concurrently work together adjusting the heart rate to meet the demands of our body even when we are sleeping, which leads to subtle irregularities of our heart rhythm.

By analyzing beat-to-beat variability (also known as HRV), we can easily estimate the ratio of activities of sympathetic and parasympathetic nervous systems. This allows us to estimate one's stress level.

Our body reacts to stress by increasing sympathetic tone. When we are stressed, our heart rhythm tends to be more stable resulting in a low variability. In contrast, a relaxed state is usually associated with a high HRV.

Using CardioMood to check your stress level

To check your stress level you can use one of our apps: HRV Lite or HRV Expert.

Here is how you can do it: 1. Wear your heart rate monitor and relax (sit in the chair or lie down) 2. Set the measurement limit to be 2 min. 3. Establish connection with your heart rate monitor 4. Click START RECORDING 5. See your heart rate graph with average stress level after 2 minutes

If you see artefacts or ectopic beats, try to eliminate them or adjust heart rate monitor to ensure good connection and repeat the procedure.

During the measurement don't change your position and avoid talking.

We estimate stress level using standard algorithm developed by a soviet physiologist R.M.Bayevsky. Normal range for stress index is 40 – 150. Values above 150 is considered to be associated with stressed condition. Values below 40 are often associated with sleep (it is like that for example if you stay awake too long).

Even though there are standards for HRV, all estimated parameters and normal ranges can vary depending on your individual features and lifestyle. Only a trained physician can correctly interpret the recording, with respect to your individual features and medical history.

Don't stress out!

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CardioMood Team

[cardiomood]

Healthy New Year brings new features to CardioMood

Happy New Year and Merry Christmas, dear CardioMood users!

Be healthy and keep fit this year with our solutions!

To tell you the truth our New Year resolution was to keep up our blog. So don't forget to visit it this year!

Some key updates made since the beginning of the month:

1. Personal account for users

Last year we tested beta version of our service but now it’s ready for you, dear CardioMood user. 

So check it out at http://home.cardiomood.com !

Here you can

view your history records

make a profound HRV analysis

get consultation from our HRV gurus - medical scientists

2. Personal cabinet for HRV experts

It’s also available on the internet: http://doctor.cardiomood.com

Here you can find expert tools for rhythmogramm analysis using Heart Rate Variability methodology.

Best wishes,

CardioMood Team

[cardiomood]

HRV Lite by CardioMood

In order to make it easier for you to get familiar with our products (e.g. advanced HRV analysis app that has been released recently), we've created a light version of the app, which is available for free.

Introducing HRV Lite by CardioMood.

Get from Google Play: https://play.google.com/store/apps/details?id=com.cardiomood.android.lite

HRV Lite for Android will allow you to:

✓ Take measurements of your HRV with unlimited durations ✓ Estimate your average stress level (Bayevsky Stress Index) ✓ Calculate all the necessary time-domain HRV parameters (mRR, SDNN, RMSSD, pNN50) ✓ Detect and eliminate ectopic beats ✓ Sync with the CardioMood cloud

Screenshots

Stay healthy!

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CardioMood Team

[cardiomood]

HRV Expert by CardioMood

We are proud to announce the release of CardioMood 2.0!

Heart rate variability (or HRV) is widely used method of analysis of the heart rate variations. HRV is one of the approaches for assessment of functional state. It allows you to:

find out your stress level

estimate your autonomic balance

early detect cardiac problems

evaluate your readiness for training

track your fitness performance

We'd like to introduce HRV Expert for Android! Support our work and download it now: https://play.google.com/store/apps/details?id=com.cardiomood.android.expert

Why 2.0?

We completely revised the structure of our old app, and added more information to the report. Our algorithms were tested against reliable ECG analysis software.

There are 7 reasons why this is the best app in HRV: 1. We use standard, widely accepted algorithms 2. Our app was tested against certified ECG based HRV software (such as CardioLabs). 3. It shows a comprehensive report (with time and frequency domain parameters) and provides flexible measurement options. 4. The application allows to export the data and report to a text file 5. This is a purely native Android app, which means you will get as good user experience as possible. 6. All your data is synchronised with the cloud, so you can have share them across our apps and have access to it from anywhere. 7. The website home.cardiomood.com will allow you to do even more!

No doubt, now this is the best app for HRV analysis for Android. We hope the app will be a good tool for your training and research.

Screenshots

Don't forget to leave a comment in Google Play.

CardioMood Team

[cardiomood]

CardioMood - way to live a healthy lifestyle

Have you ever felt overworked or exhausted? Often experience stress and headaches? Constantly feel lack of sleep? CardioMood helps to solve these problems and to organize your life in a right way.

We analyze your heart rate and give advice to improve your life quality. You'll be able to work more efficiently, always be in a good shape and good mood, be prosperous and enjoy your life. We will teach you to properly organize your day, to wisely choose a time for work and rest, to balance your intellectual and physical activities. And, most importantly - all this is personalized on the basis of your heart rate.

All you need to start is a smartphone and a heart rate sensor - for example, Polar H7. With the help of mobile app and a sensor you should make regular measurements of 2-5 minutes, and the system itself will start giving advice to you. Over time, these recommendations will be more accurate and, following them, you can experience their positive effect!

At the core of CardioMood is a modern heart rate variability methodology, actively used throughout the world. With the help of advanced algorithms developed by us, we give you the most customized and personalized advice.

CardioMood is designed to help people look at their life from a new angle . Our goal is to teach people to take care of their emotional health, to live life to the fullest and enjoy every moment!