Change your Currency:
United Kingdom (£)
£0.00 (0)
You are here: Home > Frequently Asked Questions

Frequently Asked Questions

Click on the question link which most closely matches your question and you will be taken to the relevant answer below automatically.

Heart rate variability

An overview

What do you need to use ithlete?

Choosing the right sensor for you
Which HRM straps is ithlete compatible with?

Getting started with ithlete

Quick start guides and tips
Extended User Guide
Using and maintaining your HRM strap
Time of measurement
Standing vs. sitting
Establishing a baseline
Interpreting the results
Why does the way I breathe affect my ithlete reading?
Exporting data


Not picking up a heart rate signal
No sensor found after iOS7 update
Android app license failed notice

Precision Pule HRM App FAQs

Which HRM straps are compatible?
ECG receiver operating range

Still having trouble?

Contact ithlete support
Refund policy

Heart rate variability

Heart rate variability (HRV) describes the way your heart beat varies - both at rest, and during exercise. Contrary to popular belief, the healthy heart does not beat like a metronome, but is constantly changing the time between beats in a rhythmic way. These changes are driven by the nervous system, trying to find the most efficient way for the body to operate. The fact that the nervous system makes itself visible through HRV makes the heart a wonderful barometer of how hard your body is trying to preserve its equilibrium. The higher the variance between beats the better, this shows your body is able to respond quickly to demands.

For more information on heart rate variability check out our ‘Science’ section. Plus there is an abundance of scientific research available for heart rate variability. We provide summaries of the most on our blog.

What do you need to use ithlete?

To get started with ithlete you need;

  • A compatible smartphone or tablet
  • The ithlete app
  • A HRV sensor (HRM strap & ECG receiver, Bluetooth Smart HRM or Finger Sensor)

Choosing the right sensor for you

Which HRM straps is ithlete compatible with?

Bluetooth Smart heart rate monitors (HRM)

The Cardiosport Blue is recommended for use with for use with compatible devices. We have also tested the Polar H7 and Zephyr HxM Bluetooth Smart models, both of which work successfully. Some other models of Bluetooth Smart chest strap, such as the Wahoo Blue™, do not currently support the RR part of the standard and cannot be used to measure HRV with ithlete.

Analog HRM straps

We recommend using the Cardiosport heart rate monitor strap in order to ensure the best quality reading and an accurate HRV measurement. Although you can use your existing chest strap monitor who wants to search for and put on a sweaty strap in the morning? No, we prefer to keep a Cardiosport strap next to the bed for ithlete measurements.

If you do want to use your existing chest strap monitor, the ithlete ECG receiver is compatible with most makes and models which work with gym cardio equipment. Some tried and tested models proven to work include...

  • Polar T31, T34, T61
  • Polar T31 coded (incl Wearlink)
  • Suunto Dual
  • Nike analog chest transmitter belt
  • Sigma Sport non coded
  • Oregon Scientific analog
  • Decathlon Geonaute HRM Chest belt


Occasionally users contact us to ask whether ithlete is compatible with ANT+ chest straps such as those supplied with Garmin products. The ithlete ECG receiver was designed specifically for the Polar analog standard which has been used extensively in HRV research, and is not compatible with ANT+. If ANT+ were to become a standard feature built in to Android or Apple smartphones, we would certainly make ithlete compatible but we don't plan to make a dedicated receiver for ANT+.

Getting started with ithlete

Already checked out our How to use ithlete page but still have some questions?

Quick start guides & tips

ithlete Finger Sensor

If you are having trouble taking a reading with the ithlete Finger Sensor please ensure you have checked the following tips

  • The receiver is fully plugged in to the phone, and is not blocked by a case or sleeve (should make a firm 'click')
  • The fleshy part of the left index finger is level with the end of the finger sensor
  • Make sure your hand is resting (palm up) on a hard surface and you are sitting still
If using the ithlete Finger Sensor measurements should always be taken sitting down with your hand resting on a hard surface. This is because research shows the strongest correlation with gold standard HRV measurements this way.

This video provides further guidance too...

Add Quick Start Guide

Bluetooth Smart HRM Strap

If using a Bluetooth Smart HRM strap please ensure you connect the strap directly to the app the first time of using. Pairing with the phone will not work, you need to open the ithlete app, select Bluetooth from the sensor choices and select your strap from the pop up list of detected straps within range. Upon opening the app next time, ithlete will automatically detect previously paired Bluetooth Smart straps within range. Please note: Bluetooth Smart HRM straps can only pair with one app at any time. If you have previously used another app please disconnect before attempting to pair with ithlete.

Add Quick Start Guide

ithlete ECG Receiver & HRM strap

  • The ECG receiver is pushed all the way into the phone and is not blocked by a case or cover. It has a firm 'click' when seated correctly.
  • The HRM chest strap is a compatible model
  • The ithlete logo on the ECG receiver is facing forward and that the receiver is no more than 8-10" (25cm) from the centre of the chest strap.
For ithlete the ECG receiver’s operating range is quite short, typically 8-10" (250-300mm). This is deliberate so we can get the strongest signal to measure the precise position of each heartbeat, and also so that the phone display is visible to allow the user to follow the lung animation.

Add Quick Start Guide

Extended User Guide

The ithlete User Guide provides a comprehensive overview of how to get the most out of ithlete, and includes articles by experienced coaches and users.

ithlete Guide to Training with HRVUnderstand more about over-training and training with heart rate variability.
Download the Guide

Using and maintaining your HRM strap

We recommend checking out this Tuesday Tip blog post for more information on looking after your HRM strap.

Time of measurement

We recommend taking your daily ithlete measurement first thing in the morning for two reasons; primarily to allow you to make informed decisions regarding the days workouts and also to avoid the influence of variable external factors (such as life/work stress, caffeine etc.). Some people like to do their measure as soon as they get out of bed, whilst others prefer to walk around, or do some light stretching as part of their morning routine, then do the measure.

Sitting vs. standing

First and foremost, consistent measurements are more important than position. This is because each position appears to provide important data regarding training status. Therefore, pick a position and stick to it 100% of the time for your measurements to be meaningful. Switching positions from day to day will provide skewed data and affect daily ithlete colour indications.

Most users should take their ithlete HRV measurement sitting down.

If using the ithlete Finger Sensor measurements should always be taken sitting down with your hand resting on a hard surface. This is because research shows the strongest correlation with gold standard HRV measurements this way.

If using a HRM strap extremely fit endurance athletes and individuals with low resting heart rates (<50bpm) are advised to measure HRV in a standing position. Research studies have found that HRV is distorted when lying down in people with very low resting HR (50 and under). Standing (or even sitting) will raise this by a few bpm because your heart has to work a little more to pump blood uphill. However if you find this uncomfortable or would prefer to sit during measurements that is fine – just be consistent!

Establishing a baseline

To first establish your baseline we would recommend getting started with ithlete during a recovery/light training week if possible. However that is in a perfect world and we understand it is a lot to ask of fitness enthusiasts to take a week off! So ideally just avoid very intense workouts during that time. The baseline is actually a rolling average, so as you adapt and improve the average rises ensuring your change from baseline and daily training recommendations remain relevant to your current level of fitness.

As baseline continuously adjusts, it is not a problem longer term if you start in an overtrained state; it would still guide you back to health without affecting your long term baseline and training recommendations. If you did suspect you were overtrained, then rest is needed anyhow, and the direction of the change will tell you whether you were sympathetic overreached (HRV will increase) or parasympathetic overreached (HRV will decrease).

Interpreting ithlete results

Each morning ithlete will provide you with a colour coded number (your ithlete HRV daily score). The colour refers to your change from baseline and recommended training.

  • G = Green = Go. You are sufficiently recovered, and ready to train
  • A = Amber = Active recovery e.g. light (aerobic) exercise
  • R = Red = Rest
You will also see weekly and monthly change indications. This allows you to see whether your general trend is increasing (linked to increased health and performance) or decreasing (heading towards an overtrained state.

Understanding amber increases

In general, increases in HRV represent recovery, especially if the increase is back towards, or slightly above your baseline (the blue line). Slightly above represents super-compensation of course.

Occasionally you may experience an increase in daily ithlete HRV score with an amber training recommendation. The system is then detecting a parasympathetic level much higher than baseline. In strength, power and sports requiring explosive efforts, this kind of increase is often associated with temporary sympathetic exhaustion, so the parasympathetic branch of the body's regulation system is seen to dominate.

Decreasing HRV even after rest

Heart rate variability is a great measure of stress and not all stress is physical. Whilst you may be recovered from the physical stress placed upon your body from workouts have you considered cumulative stress? Cumulative stress is what HRV actually measures and is also affected by mental and chemical stress. So next time your HRV starts to decline but you feel ready for physical exercise you might want to think about your diet and life stressors.

Why don’t I get the same measurement if I repeat the readings?

If the HRV number decreases and / or the resting HR increases during multiple readings, then you are not relaxed enough. HRV is a sensitive measure of stress, whether physical or mental, and anxiety about the HRV reading will lower it. You need to think of your ithlete HRV measurement more like a blood pressure than an HR measurement (in fact heart rate variability and blood pressure are regulated by exactly the same parts of the nervous system). Many people have heard of 'white coat hypertension' - that's when your blood pressure is higher in the Doctor's office simply because you are anxious. That same anxiety or lack of relaxation will also lower your HRV.

We strongly recommend doing one reading and not repeating without leaving a 5-10 minute break if you really think the first saved measurement was wrong. If you are disturbed during your first measurement simply select 'Cancel' during the reading and repeat the measurement.

Why does the way I breathe affect my ithlete reading?

Heart rate variability and breathing are intimately connected, and that is the reason we included the paced breathing animation to provide consistency in the measurement. The chosen breathing rate is based on highly respected research into the effects of breathing rate on HRV; however some people feel it is too fast for them, especially if they are practised deep breathers. You can choose your own breathing rate if you prefer, but HRV is a sensitive measurement, so keep it consistent from one day to the next, and never take HRV readings when breathing irregularly.

The following quote is from Dr Liz Miller, a former neurosurgeon, psychologist & author (and ithlete user!):

“The emphasis is getting people to breathe right, which maximises HRV because breathing profoundly affects HRV - Heart Rate Variation is largely due to the changes that occur during breathing - breathe in - Heart Rate goes up - breathe out - Heart Rate goes down. These changes are healthy, normal and partly relate to the mechanics and partly to the autonomic (sympathetic and parasympathetic) nervous system. The greater the changes between breathing in and breathing out, the healthier and fitter your heart, lungs and autonomic system. In other words heart rate variability measures the amount your heart rate changes from moment to moment. Most of this difference is due to breathing patterns.

Any change in mental state, even if you are an Indian meditation guru will change your pattern of breathing - the two are inextricably linked! Anxiety produces shallow fast breathing, calm produces slow deeper breathing. The slower and more consistently you breathe, the greater your HRV at any moment, up to a maximum that relates to your own personal fitness and gives you an ithlete number.

Inconsistent breathing, even slight, profoundly affects HRV. Although most people learn subliminally that to get their best reading, they need to follow the animation on the screen, and breathe in a slow and measured fashion, it is possible to mess with your HRV by fractionally altering your breathing. This will happen if you are anxious, tired or otherwise stressed.

From a user point of view - HRV needs to be a peaceful ritual. You sit and relax for a couple of minutes, watch the graphic on the screen and then when you are feeling calm, join in breathing with it and then when you are happy your breathing is nicely synchronised, switch on the device and measure your HRV.”

You can also check out this Tuesday Tip blog post for more information on time how breathing effects HRV.

Exporting data

All of your ithlete readings can be exported via Dropbox or to the email address of your choice. That could be a friend, coach, or yourself in order to include in your training log or just to keep a safe copy. Team App subscribers can also export to their team account. To do so please collect the username and password from your coach.

The file is in .csv (comma separated variable) format and can be imported into many spread sheet programs such as Excel, Numbers and Open Office. These programs will do some basic formatting for you when you open the file, and will put the Date, Time, HRV and resting HR into separate columns. The final column is made up of the Indicator letters that ithlete uses to make recommendations on your training for that day. These are interpreted as follows:

  • G = Green = Go. You are sufficiently recovered, and ready to train
  • A = Amber = Active recovery e.g. light (aerobic) exercise
  • R = Red = Rest
  • N = Not the first reading of the day = Not used in the ithlete chart


Not picking up a heart rate signal

If the heart in the bottom left of the measurement screen stops beating then the signal has been lost. If using a HRM strap ensure that the skin contacts are moistened and that the strap is tight without being uncomfortable. Check the Quick start tips for your sensor type above.

No sensor found after iOS7 update

Due to a new privacy setting after updating your device to iOS7 you may need to change your settings. Go to Settings > Privacy > Mic > select ithlete and switch it on. Once you reopen the ithlete app it should recognise your sensor.

Android App licence failed notice

As part of the user validation process, the app does a weekly license check with Google Play to make sure only paying customers can view the Chart and Edit screens. This license check involves connecting to Google Play and sending over user data. In return, Google Play then effectively sends back a yes or no for that particular user account. If no, we display a license failed notice to the user and block access to these screens. If yes, the user will then be able to view these screens until the next license check. This is all done ‘silently’ in the background and the user will only know about it when the license check fails.

Reasons for failure

  1. No internet connection
  2. The user’s Google Play account is invalid
  3. The user has removed/signed-out of their Google Play account on the device they’re running ithlete
  4. License service issue with Google Play

Precision Pulse HRM App FAQs

Which HRM straps are compatible?

Works with ALL Polar HR belts (not WIND), Suunto Dual belt, plus many others. Precision Pulse is now fully compatible with Bluetooth Smart heart rate chest strap monitors. All HRM straps which work with ithlete (above?) are compatible with Precision Pulse.

ECG receiver operating range

For Precision Pulse the operating range is longer, typically 31-36" (800-1000mm). This is typical for analog heart rate monitors that are sensitive to interference. Precision Pulse has an automatic gain control system to minimise interference when the receiver is close to the body, but you will notice the signal drops out temporarily as you move the phone away from the body quickly. It will re-establish after 2-3secs.

The range achieved does depend on the type & quality of the chest strap being used. The Cardiosport model we supply as well as the Polar T31 models offer the best range we have seen.

If you are having problems with range or interference and have a compatible device we would strongly recommend upgrading to the Cardiosport Bluetooth Smart HRM.

Still having trouble

Contact ithlete support

If the tips above haven’t resolved the issue please drop us an email. We will usually get back to you within one working day.

What is your refund policy?

If you change your mind about your purchase, please return the unused goods to us with the original order reference within 8 working days from receipt and we will offer you an exchange or a full refund. This does not affect your usual consumer rights, including your right to claim a replacement, repair, or refund where the goods are faulty or not accurately described.

Your contract with HRV Fit Ltd is regulated by the UK Consumer Protection (Distance Selling) Regulations 2000 and the Electronic Commerce (EC Directive) Regulations 2002.

Top of Page
Watch our HRV App Video
"The new features are brilliant! Like the way you can steady your heart rate using bpm before doing the hrv measurement. Also like the dropbox features. "
Rory Arneil,
"I just changed my testing protocol to do my morning test standing up. When I first got iThlete, I tried doing it standing but my results weren't consistent. I started to do it sitting and it..."
David Burton, Track Athlete
"your device has been a real godsend after a severe bout of overtraining syndrome last year"
Sarah Ledbury, Triathlete
"Stress management in my body is one of my big challenges since I'm now hormonally overdosed, due to past cancer in my thyroid. I was desperately searching for such a tool to track HRV for a..."
Rémy Touzé,
Customer Reviews
"Works well most of the time. "
"Very easy to use, great accurate results and it makes knowing whether to train or not really simple."
» See more Reviews
Case Studies

Matthew DeGiacomo

Read Full Case Study

Mark Williams

“The main thing with ithlete is that you learn about... Read Full Case Study

» See all Case Studies
Watch our Precision Pulse Video
Press Articles
"ithlete is an application for sports people and tells you how hard you should train"
Runners World (UK) 03/2010
"I was able to train harder after days on which I'd been advised to ease up."
» See all Press Articles
© 2009-2014 HRV Fit Ltd. ithlete is a trademark of HRV Fit Ltd. All rights reserved.   Terms and Conditions   Privacy Policy   XML Sitemap   Accessibility