Introducing the Go/NoGo Task: A New Way to Assess Cognitive Readiness with Rewire

At Rewire, we are constantly striving to provide you with the best tools to enhance your performance and optimize your readiness. That’s why we are thrilled to announce the latest addition to our Readiness Assessment: the Go/NoGo task. Let’s dive into the details:

What is the Go/NoGo Task?

The Go/NoGo task is a response inhibition task in which your goal is to rapidly identify and respond to the “Go” stimuli (blue shape) as fast as possible, while withholding your response to the “NoGo” stimuli (red shape). Rewire measures your reaction time when correctly responding to the Go stimuli, lapses in concentration, and the number of incorrect responses (misses). Over a rolling 30-day period we’ll create a baseline and utilise that to provide a personalized analysis of daily cognitive readiness, helping you make well-informed training and recovery decisions.

Why is Cognitive Readiness Important?

Mental (or cognitive) fatigue impairs physical performance. This is something we all (likely) have anecdotal experience with – try training after a long hard day at work, it’s going to feel harder, and you’re not going to able to achieve your best. This was cemented within research with a landmark 2009 study by Samuele Marcora et al., providing initial evidence that ‘mental fatigue limits exercise tolerance in humans through higher perception of effort rather than cardiorespiratory and musculoenergetic mechanisms’ with many more studies since highlighting the negative effect that mental fatigue has on athletic performance.

What Can We Do About Low Cognitive Readiness?

The good news is that despite the negative impact that cognitive fatigue has on our performance, there are a variety of strategies that can mitigate the negative effect of cognitive fatigue. We’ve built these protocols into our Mindset Recovery system providing a way to optimize your state for workouts, sleep, focus, relaxation and more – with sessions utilising strategies like Binaural Beats, Guided Breathing, Self-Talk, Visualization, and Subliminal Priming. Our recommendation engine also provides a personalized recovery recommendation based on your current readiness state, key areas of need, and your goal.

Integrating the Go/NoGo Task into the Readiness Assessment

The Go/NoGo task seamlessly integrates into our Readiness Assessment, providing an alternative to the Reaction Time task. In addition to the cognitive assessment, our Readiness Assessment takes a holistic approach, encompassing cognitive, emotional, and physical domains. By combining multiple data points, including the results from the Go/NoGo task, heart rate monitoring, training load, and self-assessment questions, Rewire provides you with a well-rounded assessment of your overall readiness.

Get Started with Rewire and the Go/NoGo Task

If you’re already a member of Rewire, simply update your app and start a Readiness Assessment to select and use the Go/NoGo task. Please keep in mind that since the Go/NoGo task is a new task, we’ll need to calibrate your baseline independently to the reaction time test. This process is initially 4 days and improves over the course of a rolling 30-day period. During the 4-day calibration, your cognitive score will be based on Mental Load and Sleep. You can always switch back to the Reaction Time task via Settings->Readiness Assessment Preferences.

If you haven’t joined us yet, now is the perfect time. Sign up now and unlock your full potential

Individualisation and Modification of Training Based on Readiness and Individual Responses to Stimulus With Rewire

With each passing month there is more and more evidence in support of the use of HRV guided training for athletes. Part of this is driven by the increasing interest in HRV as a measure in health and performance, but part of it is also probably due to the intrinsic ‘sense’ it makes. That is; not everyone adapts to the same stimulus the same way and everyone deals with life stressors differently. In fact, if you speak to most coaches these phenomena are deeply ingrained in their understanding of adaptation, the challenge has been how to quantify this and adapt as a result. 

This was the basis for Rewire’s readiness tracking. It was built on the concept of blending both objective physiological parameters with subjective and emotional factors, which is still quite unique in the industry. As is the appreciation of the two and their impact on eachother, perhaps due to modern culture’s mind-body dissociation. 

To this point, a bulk of the research regarding HRV guided training has used HRV as the sole measure to adjust training (either in an acute time frame with acute changes to HRV or a longer term time frame based on longer term trends) and has mostly cut back or reduced training intensity based on this. In reality many coaches would likely integrate subject measures with these sorts of objective measures such as resting heart rate and HRV as well as modify training in more ways than just reducing load on days of poor readiness. 

A recent study from Nuuttila Olli-Pekka and colleagues has taken a very coach oriented view on readiness when it comes to HRV guided training. 

The basics of the study:

  • Runners were split into two groups, one followed a set program and one adjusted training around their HRV, heart rate-running speed index (a measure of the relationship of running speed to heart rate)  and subjective measures of readiness. 
  • In the group who adjusted training, this was done twice a week and saw either an increase, maintenance or decrease in training based on the measures mentioned. 
    • This is of specific note given usually HRV guided training studies use only low HRV to reduce training load, not the opposite. 
  • They trained for 15 weeks, with pre and post intervention testing
  • Top speed on a treadmill and 10km time trial were the outcome measures

What they found:

  • All runners improved
  • The magnitude of improvement was greater for the group with modified training in the 10km time trial 
  • The proportion of high responders (those who had significantly larger improvements) was more in the modified training group (50% vs 29%)
  • The modified training group had fewer low responders (0% vs 21%)

Some thoughts and takeaways:

  • Generally training improves performance, so the global improvement is expected but the difference in the groups is key
  • Using modified training had greater upside (high responders) and lower downside (low responders), crucially there were no non-responders

So to summarize, modifying training to match readiness showed increased performance and improved all participants’ performance. This is very rare in any intervention, let alone one that only takes a few minutes! 

If this, in combination with the fact that Rewire both tracks these metrics and provides actionable insights around modification of training and preparation for training on different days, doesn’t make you want to use Rewire then the next study will help really cement this. 

Jens Voet and colleagues’ 2021 paper showed the disconnect between the training prescription of the coach and the way this was executed by the athletes (in this case, semi-professional cyclists) with respect to RPE. This difference was significant, and importantly, differed between individuals. It likely reflects, at least in part, the disconnect between prescription of external workloads and training responses they induce (internal workloads). 

To simplify, the intention of the coach when prescribing sessions was rarely the reality, and the magnitude of this difference was individual between athletes. Again, for most coaches this probably makes some sense upon reflection. But the challenge is quantifying this gap and the bigger challenge is adapting things going forward to the athlete. 

Enter Rewire. 

The algorithm used in readiness tracking by Rewire adapts to you in that your individual variation is scaled based on your normal ranges, because everyone’s responses differ. 

This readiness measurement drives mindset recovery and pre-workout priming recommendations to help you get the most out of training or indeed recover better for the day. That’s right, Rewire provides actions to take based on readiness, not just a readiness score for you to try and understand. 

Additionally, the gap between intended session difficulty and actual difficulty is currently tracked when undertaking Neuro-training and is something that is in the roadmap for inclusion at a later date for the coaches dashboard for other training sessions.

So with this in mind, why not start your Elite trial of Rewire today?

Don’t forget, Rewire is about more than just readiness tracking and pre-training preparation! Recovery sessions are prescribed thanks to integrations such as Garmin and Strava because training is about repeated efforts over weeks and months, not just every now and then. This is all without mention of Rewire’s key mental fitness focused Neuro-training, which improves mental endurance. 


Olli-Pekka N, Ari N, Elisa K, Keijo H, Heikki K. Individualized Endurance Training Based on Recovery and Training Status in Recreational Runners. Med Sci Sports Exerc. 2022 Aug 13. doi: 10.1249/MSS.0000000000002968. Epub ahead of print. PMID: 35975912.

Jens G. Voet, Robert P. Lamberts, Jos J. de Koning, Jelle de Jong, Carl Foster & Teun van Erp (2021) Differences in execution and perception of training sessions as experienced by (semi-) professional cyclists and their coach, European Journal of Sport Science, DOI: 10.1080/17461391.2021.1979102

This indicates that the relationship between RPE and iRPE is unique to each cyclist. Both the different execution and perception of the training programme by the individual cyclists could cause an impaired training adaptation.


Readiness Tracking: How and When to Use the Different Aspects of Rewire


Readiness tracking is a crucial part of athletic performance preparation. This is abundantly clear from the increasing adoption of various readiness apps and trackers. For more on why Rewire is the app of choice when it comes to comprehensive readiness tracking see this article.

But tracking readiness is only one part of the equation, it is what to do with this information that is key to performance impacts that can be seen from readiness tracking, and what is lacking from some of the trackers.
More succinctly, “what should you do when your readiness is low?”

Given the way Rewire tracks readiness this article will cover a variety of scenarios:

  1. How should you action overall readiness?
  2. How should you action cognitive readiness?
  3. How should you action low physical readiness?
  4. How should you action low emotional readiness?

It should be noted, but perhaps goes without saying, that managing/avoiding excessive stressors in areas like the emotional realm for example is obviously ideal but not always possible, especially for non-professional athletes. 

Overall Readiness

Overall readiness is an indication of the global state of your readiness for the day. It is worth considering this as well as the breakdown thereof, particularly if you have flexibility in regards to work and training schedules. 

What to do with High Overall Readiness

This is a green light, go for it. 
And to be extra prepared for this, complete a pre-workout priming session. 

Note, this may also be a good day for some extra Neuro-training as outlined in this article

What to do with Low Overall Readiness

The first thing to consider here is ‘why’. What is impacting your overall readiness in a negative way. This has two components, these are; which aspect (or aspects) of Rewire’s readiness breakdown is impacted, but also what is driving that specifically. For example you may have low physical readiness due to poor sleep or hard training. 

The reasons to explore this are to better understand how your lifestyle is impacting you to allow you to consider how you may avoid days such as this as well as work out the course of action you can take for that given day.  

With low overall readiness, it is worthwhile to consider how you may want to modify your training and other lifestyle factors for the day. This may include removing some intensity and/or volume from training, it is also probably a day to consider reducing or removing any planning neuro-training. Similarly if you have the luxury of modifying your other life stressors this would be a good time to do so. 

Regardless of whether you are able to or willing to take the above action and especially if you can’t, this is the time for a mindset recovery session. Rewire recommends mindset recovery sessions specifically geared towards helping you tackle the day given your personal readiness. 

Of course, it should go without saying that each part of the breakdown of your overall readiness should be considered in combination with your overall readiness and other parts. These are all interconnected, but the following advice gives some insight into these aspects in a vacuum.

Cognitive Readiness

Cognitive readiness reflects the mental load you have been under predominantly but will reflect the fatigue your central nervous system is experiencing too. This is particularly important for athletes who are planning highly fatiguing central nervous system training such as speed and power training. Or for the time-crunched athlete balancing busy work days and training.

What to do with High Cognitive Readiness 

This is an ideal time to do some neuro-training. Take the opportunity to get some good neuro-training done, whether combined with physical training or separately depending on training plans for the day, physical readiness and preference. 

What to do with Low Cognitive Readiness 

As mentioned above in the overall readiness discussion, considering the source of this low readiness is key to your progress. This may allow elimination or modification to prevent the issue, or indeed alteration of training plans around the stressor better, proactively rather than reactively. 

When considering low cognitive readiness your relationship with training and it’s cognitive burden in the context of your full day is extremely important. For some people training is much more cognitively burdensome than others, and this would greatly modify your decision making around this readiness score. 

Broadly though, it is likely that modifying or removing your neuro-training plans for the day and completing a mindset recovery session are the two first steps in this case.

Physical Readiness

Probably the most familiar of the breakdown components of the Rewire readiness score. This is the most prominent in most athletes’ minds but should be considered in context of the global training program also. There are times where low physical readiness may be the plan and goal. 

What to do with High Physical Readiness 

High physical readiness may be the license you want/need to try and do a little extra in training depending on the way your program is structured. If not, it is definitely a green light to get your training session done well. 

On days with good physical readiness, a pre-workout-priming Mindset Recovery session will help to really knock the training goals for the day out of the park. 

What to do with Low Physical Readiness 

Days with low physical readiness are days to really take stock and make ground on your opposition. Yes, you read that right. These days offer some great opportunities to you via a mixture of smart training and using Rewire to its fullest potential to really gain ground on your competition. 

Modifying your training on days when your physical readiness is low is a key part of success. This may include reducing intensity, which is covered in the above linked article regarding Rewire as a readiness tracker. 

The real strength of Rewire, though, is that you have something you can actively do to aid your progress here, not just removal of training load. There are a few ways to use Rewire for this: firstly using mindset recovery sessions you are able to better recover from your fatigued state and secondly (especially on days with good cognitive readiness) you can undertake more neuro-training. 

So whilst you may be modifying your physical training stimulus you do not need to be modifying your total training stimulus, or perhaps better said, you are always adapting, just to different stimuli. 

Emotional Readiness

Often harder to appreciate without specific reflection (another strength of the Rewire system), emotional readiness provides some key insights which may be differently relevant in different user populations. Sources of emotional fatigue can vary greatly and are often quite specific to the individual. The impact that emotional fatigue can have on performance is both very real and of significant consequence given the narrow margins in sport.

For some the nature of their endeavors may mean that they find themselves in a relatively emotionally stable situation. This can be by chance or through design, but even those who are typically more emotionally stable might need to be able to perform with lower emotional readiness in the acute time frame. Examples of this may include tactical operators, health care professionals and some sports people. 

In contrast, others may see a less stable emotional readiness based on external factors such as work or relationships, which means their readiness is more regularly impacted by their emotional state. 

It should also be noted that it is rare for emotional readiness to be impaired in isolation, particularly in professional athletes. Similarly it should go without saying that considering the source of emotional burden should also be sought in all cases of low emotional readiness (though there is merit in finding sources of high emotional readiness too).

What to do with High Emotional Readiness

 High emotional readiness should be seen as an opportunity to push yourself in endeavors that may not traditionally be seen as training (and may not be training). It may be a day to try to level up in our neuro-training (if cognitive readiness is appropriate) or take the time to work on some creative endeavors on the work front (for the non-professional athletes).
Having high emotional readiness can at times negate the need for pre-workout priming to a degree given this can be paired with a high degree of excitement/motivation for training.

What to do with Low Emotional Readiness

Given the intertwined nature of emotional readiness, it may be worthwhile considering modifying training as appropriate when considering other aspects of readiness. Regardless, if this is truly isolated low emotional readiness, mindset recovery sessions will aid greatly in this as training with low emotional readiness can be very draining. Similarly if the session is important and cannot be modified, pre-workout priming will play a large role in preparing better for the preparation as performance with a high emotional fatigue is exceedingly difficult. 

This is unlikely a good time to do much neuro-training and if this is undertaken, lower levels should probably be done given the high potential for frustration associated with difficulty in these exercises. 

Take Home Message

Whilst modification of training is usually an easy answer, it is not always possible. Similarly it may not be optimal in some cases, particularly given the part time nature of many athletes using Rewire. This is where Rewire can aid in the athlete’s journey, by providing actionable solutions and aids in preparation and recovery from training. 


Dr David Lipman is an Australian trained Medical Doctor, Podiatrist and Exercise Physiologist. He has worked with athletes of varying levels in all 3 roles. He is an ultramarathon runner, avid physical activity advocate and is passionate about performance in all people.

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Why is Rewire The Best Readiness Tracker?

The list of available wearable devices, apps and gadgets is seemingly ever growing. Each seems to have a slightly different method, pitch and demographic. 

Surely it must be simpler than this? 

Yes we all have different goals, but performance, whilst there are different components to it, largely requires the same thing: being physically, emotionally and cognitively ready to go. 

Yes of course, it is more than just readiness, performance requires preparation of all sorts, but this is the price of entry, without this there is no start. Once this is done though, performance hinges on readiness to do so, and being able to respond to challenges that arise during the performance. 

As a younger athlete, it can be easy to think that performance is only about training, and only physical in nature. As time passes and you gain experience it becomes quickly apparent that readiness fluctuates and that the impact of mental and/or emotional fatigue can be real and impactful. 


What are the Components of Readiness?

The physical aspects of readiness are probably the things you have already heard about and know about. These include training load for the previous day, soreness, resting heart rate, heart rate variability (HRV) and sleep. 

The cognitive components of readiness are much less talked about but a crucial aspect of readiness that helps form the complete picture required to truly discern readiness, especially when life stressors are more than just training related (which is almost always the case). These components include reaction time and accuracy, mental load, and sleep. 

When considering readiness, ignoring the emotional aspects of readiness (and thus performance) is outdated at best. The new generation of elite coaches and athletes is increasingly realising the importance of emotional aspects of performance and working hard to both monitor, train and control these to be able to hone them for top performance. These components include; rest, readiness, frustration and stress. 

But Some of these are Subjective? 

That is a good thing, not a bad thing! 

There is a tendency to believe that athletes are robots and the body is a machine, this is absolutely false. Sometimes the subjective measures of wellness and readiness are more important and sensitive than the objective ones such as HRV.1

Readiness Sounds Complicated? 

Simply put, it is. 

The human body is complicated enough, getting it to perform in any facet of life is another layer of complexity on top of this. 

Ultimately there is no one measure that tells the complete story, the combination of all of these measures, from all of these aspects of readiness gives the most complete picture of readiness possible. 

We use a holistic approach to help you achieve maximum human performance. 

Rewire – The answer

Rewire was ultimately created with the understanding that performance has many factors that are not physical. The best physical monitoring was added to evidenced based subjective scores, in addition to newer concepts to cover the three domains of fatigue and readiness previously mentioned; physical, mental and emotional.

This all combines to give you the most accurate readiness tracker on the market.  

Rewire – How does it work? 

Each morning you complete a reaction time test, this is integrated with other physical measures and sleep. Following this test, there are a set of questions that cover training load, mental and emotional fatigue. 

You are then scored for readiness overall and in each individual realm; physical, cognitive and emotional. 

These scores are all compared to your baseline, because there is a huge deal of individual difference in many of these measures. 

The beauty of all of this is that you can track all of these factors as a group and individually, better understanding your health and readiness data. 

So my Readiness isn’t good, what do I do now? 

Emerging evidence suggests that there is some value in training based on readiness rather than a rigid program.2,3 Preliminary evidence looks as though those using a readiness based program had fewer injuries and outperformed or at least matched the group in the study using a rigid program. The key here being the readiness based program had less volume as a result of doing less on days when readiness was lower. 

Beyond this though, Rewire helps you perform via using your readiness results and key goal for the day to then prepare a personalized recovery session to help you better achieve your selected goal for the day given your readiness assessment. These sessions use a mixture of methods such as different breathing patterns and neuropriming to help you optimize your day. This is because we realize that not everyone has the luxury of moving their training around but also because these will help you better achieve your goals regardless of training. You may have a low readiness and decide that day’s goal is then recovery, we can help.  

Sounds Good, but I am not that Serious of an Athlete 

The modern world and modern life mean that now more than ever we are under more stress. We have more going on, more to be concerned about and more to get done. Given all this, it’s arguable that readiness has never been more important for the population, regardless of athletic goals. In fact, given readiness may actually be easier to predict in professional athletes given athletic performance is their job, the components thereof including things like recover and readiness optimization. In contrast, weekend warriors or recreational athletes often have many other stressors that are higher priority to them and thus should really consider the role of these in their readiness but also how much training stress they want to take on given their priorities may be orientated elsewhere. 

What I want from whatever devices I’m using is that it’s looking at the whole person.  Right, that it’s not compartmentalizing my physical wellbeing or my emotional wellbeing. And I think that what you and your team have built is an amazing platform. That really is whole-person focused
Tammy Abbott-Thiel, MSW, LMSW

Given the increasingly taxing and stressful nature of modern life and the will to perform that most if not all of us have, it seems critical to both track readiness and remedy poor readiness. Luckily this is now available to you through Rewire. Test it today and start to see the benefits of applying stress appropriately rather than fighting against your body. 

If you’re already a Rewire member (and reading this on mobile), tap here to take your Readiness Assessment. If you aren’t a Rewire member yet, tap here to sign up today!

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  1. Saw AE, Main LC, Gastin PB. Monitoring the athlete training response: subjective self-reported measures trump commonly used objective measures: a systematic review. Br J Sports Med. 2016 Mar;50(5):281-91. doi: 10.1136/bjsports-2015-094758. Epub 2015 Sep 9. PMID: 26423706; PMCID: PMC4789708.
  2. Peter Düking, Christoph Zinner, Khaled Trabelsi, Jennifer L. Reed, Hans-Christer Holmberg, Philipp Kunz, Billy Sperlich,Monitoring and adapting endurance training on the basis of heart rate variability monitored by wearable technologies: A systematic review with meta-analysis, Journal of Science and Medicine in Sport,2021,
  3. Javaloyes A, Sarabia JM, Lamberts RP, Moya-Ramon M. Training Prescription Guided by Heart Rate Variability in Cycling. Int J Sports Physiol Perform. 2018 May 29:1-28. doi: 10.1123/ijspp.2018-0122. Epub ahead of print. PMID: 29809080.

Dr David Lipman is an Australian trained Medical Doctor, Podiatrist and Exercise Physiologist. He has worked with athletes of varying levels in all 3 roles. He is an ultramarathon runner, avid physical activity advocate and is passionate about performance in all people.

Join Our Community Today!

Why Heart Rate Variability (HRV) is a Key Parameter in Rewire’s Readiness Score

If you are an athlete (of any level) you have most likely tracked your workouts in a number of ways. From subjective metrics such as the rate of perceived exertion (RPE, or how hard a workout feels), to distance, duration, power, heart rate, pace or speed, as well as compound metrics such as Strava’s Relative Effort or Training Peak’s TSS, these can all serve a purpose in our quest to quantify the stimulus we apply with training. 

However, an equally important (or maybe more important?) question we want to answer is the following: how are you responding to training? After you went out for your session, did your body bounce back from that homeostatic disruption? How long did it take? Are you ready for another high intensity session or should you take it easy another day or two?

Being able to answer these questions can help us avoid a potential state of negative adaptation and hinder performance outcomes in the long term. Here is when Heart Rate Variability (HRV) comes to the rescue. 

What is HRV?

HRV is a term that refers to ways to summarize in a number the variability between heartbeats. The variation between heartbeats results from the activity of the autonomic nervous system in response to stress. As the body is continuously re-adjusting to maintain a state of balance, called homeostasis, heart rate, blood pressure, glucose level, hormones, etc. — react to the challenges we face and the autonomic nervous system works to keep everything in balance so that we can function optimally (e.g. do not develop chronic conditions, or improve our performance). Heart rhythm (and therefore HRV) is regulated by the parasympathetic branch of the autonomic nervous system, the one in charge of rest and relaxation. Hence, measuring HRV is an effective way to capture how the body is doing while trying to maintain a state of balance in response to different stressors (training, lifestyle, etc.).

Example of a few seconds of ECG data, including detected beats. The time differences between beats are called RR intervals and are the basic unit of information used to compute HRV. We need several RR intervals to be able to compute your HRV. This is why HRV needs to be computed over a certain amount of time, typically between 1 and 5 minutes.

​In particular, a reduction in certain HRV features typically means that parasympathetic activity is reduced, and therefore we have not fully recovered or in general, there is more stress in our lives. At rest, the body is predominantly parasympathetic, which is why HRV analysis today is mostly focused on identifying reductions in parasympathetic activity, captured by features such as rMSSD (the root mean square of successive differences in RR intervals). The use of rMSSD is motivated by physiological mechanisms: the vagus nerve acts on receptors signaling nodes to modulate pulse on a beat to beat basis while sympathetic activity has different pathways with slower signaling. Hence beat to beat changes captured mathematically by rMSSD reflect parasympathetic activity, also called vagal influence. 

This means that when we train or face other stressors, HRV is typically reduced at the acute level (during and right after the stressor). Additionally, if the stressor is particularly large (say, a hard race), or if we are responding poorly to a series of stressors (for example a block of high intensity sessions), HRV can remain suppressed for several days or longer. This is a typical sign of negative adaptation, something we can avoid by better managing and adjustring training, based on our unique physiological response. 

What about non-training related stressors?

One of the key aspects of measuring HRV and using it to gauge readiness or guide training, is its ability to track your stress response regardless of the source. What does this mean? No matter if stress comes from training, work, getting sick, poor lifestyle, or some unexpected event, it will have an effect on our ability to cope with additional stressors and perform. HRV is an overall marker of stress and will be affected by pretty much any factor that has an influence on your autonomic nervous system, making it a great tool for training management.

How can you measure your HRV with Rewire?

HRV forms a part of Rewire’s Readiness Assessment and can be measured live in the background from your Bluetooth Heart Rate Monitor. It can also be read from a health app like Oura or Apple Health. We have seen how HRV is a global marker of stress and also how it is typically impacted acutely by any sort of stressor. This comes at a cost: we cannot just measure HRV anytime and use the data reliably, as HRV will typically reflect changes in heart rate modulation due to a myriad of transitory stressors we might not be really interested in (e.g. having coffee, or walking up the stairs). Timing of the measurement becomes key if we want to assess baseline physiological stress in response to larger acute and chronic stressors, and use this data for daily adjustments. 

Measurement time

Almost the entirety of research up to date has been carried out with morning HRV measurements, hence this is typically the preferred protocol and also what is implemented in Rewire, where you can also set reminders to help you make the morning readiness assessment a part of your daily morning routine

The Readiness Assessment should be taken first thing in the morning, while in a rested physiological state. While in the past subjects in clinical studies were asked to go to the lab, avoiding eating, drinking and exercising in the 2 hours preceding a measurement, waiting between 10 and 30 minutes before the measurement to get back into that relaxed state, things are much simpler now due to the technological improvements that allow users to measure simply using their phones. Ideally, measurements should be taken as soon as a person wakes up, while still in bed. The morning routine, or having a standard measurement protocol should sound familiar in many situations, for example measuring weight before breakfast, measuring blood pressure in standard conditions (sitting, arm position, etc), and similarly, assessing readiness to determine the impact of training and lifestyle on physiological stress and recovery needs.

Body position and measurement duration

In terms of body position, lying down, sitting or standing are good alternatives, but in case you do not lie down, make sure to wait a few seconds before measuring, and use the same body position each day. Several studies have also shown that for time domain features representative of parasympathetic activity, such as rMSSD, the most commonly used metric in today’s tools, 60 seconds are sufficient. 

Measurement Frequency

Measuring Readiness daily is best to obtain useful data as it establishes a strong baseline for HRV. It also means you can check in regularly with your readiness, allowing you to make smarter training and recovery decisions. Since Rewire also collects a range of cumulative data points such as training load and mental load, checking in daily ensures that there is a more complete data set involving the highs and lows of your training and work. Measuring daily is also often easier to remember, since it can form a part of your regular morning routine.

What to do (and not to do) while measuring 

During the assessment, movement should be avoided, but there are also other aspects that can trigger artifacts and require a little more attention. In particular, yawning and swallowing should also be avoided, the latter for example causes a sort of instantaneous bradycardia that can affect the measurement. 


HRV is affected by breathing. The question of using controlled or paced breathing or breathing naturally needs to be analyzed in the context of our target application, which is measuring physiological (chronic) stress first thing in the morning, longitudinally within an individual. One of the main reasons behind using paced breathing is that it is supposed to make the measurement more reliable and improve measurement repeatability. In our experience, this is not the case and letting people breathe freely feels much easier to most. In our tests we have highlighted how self-paced and paced breathing result in the same differences between consecutive measurements, hence proving that one way or the other is as effective. Thus, Rewire does not use paced breathing as part of the readiness assessment. 

How can you use the data to adjust training?

At the beginning of this blog, I covered the physiological underpinnings of HRV measurement as well as key aspects of data collection: context and best practices. By following best practices meaningful data points truly representative of physiological stress can be collected. As technology today allows for easy data collection, many of the basic physiological mechanisms behind applied use of HRV (for example the acute drop in HRV after hard workouts) have been successfully identified in user-generated data. These types of analysis provide further evidence of the effectiveness of today’s technologies in capturing individual responses to stress. ​It’s important to remember that physiology is complex, and while acute stressors (such as a hard workout) and the resulting HRV changes are often repeatable and easy to understand, there might be other factors behind the relationships that we are seeing (or not seeing) in our data. No stressor acts in isolation, there’s always something going on with our lifestyle, training, health, and so on.

Let’s look at how we can use the data to adjust training. In the past decade, we have seen how HRV has been used to capture changes in training load, fitness and performance. In a landmark study, Kiviniemi et al. proposed a first protocol to guide training based on HRV readings, and analyzed changes in training load and VO2max in recreational runners following an HRV-guided program, compared to controls following regular periodization. The authors state that the basic idea of HRV guided training was to decrease the training stimulus when HRV decreased and maintain training stimulus high when HRV remained the same or increased. Often, HRV-guided training results in lower frequency of high intensity exercises compared to the control group. This is a common theme as most protocols aim at avoiding the application of too strong a stressor (e.g. a hard session) when the athlete is not physiologically ready (e.g. when HRV shows high stress present on the body). Based on this data, HRV guided training may adjust both the timing and amount of high-intensity exercises at individual level. Yet, in these studies, performance for the HRV-guided group improved, showing how the timing of the high intensity sessions does matter

Rewire uses HRV as well as other objective and subjective measures to provide you with training and recovery guidance. Readiness-guided training aims at providing the most appropriate training stimuli in a timely manner, when the body is ready to take it, so that positive adaptation will occur, leading to better health and performance outcomes.

After the initial studies by Kiviniemi et al. most researchers shifted their approach to one less coupled to day to day variability and acute stressors, trying to look at medium and long term trends and more significant stressors that might affect physiology chronically. With the new approach, we do not really care if a single daily score is below baseline, what we care about is that the baseline itself does not go below normal values. Intuitively, for the baseline to go below normal values, we need quite a few “bad days” (low HRV scores), therefore adjustring training less often and only when a stronger negative response is present.

​Vesterinen et al. were able to show improved performance for the HRV-guided group using this protocol. In particular, the number of high intensity workouts was lower for the HRV-guided group, but despite the lower amount of high intensity exercise, the group was able to improve running performance over a 3000 m time trial. In a similar study, Javaloyes et al. examined the effect of training prescription based on HRV in road cycling performance. After 4 weeks baseline measurements, 17 well-trained cyclists were split into two groups, HRV-guided and traditional periodisation group. The training program lasted another 8 weeks, and performance measures were taken before and after the 8 weeks in both groups. In the study, the HRV guided group improved peak power output (by 5%)  and 40 minutes time trial performance (by 7%), while the traditional periodisation group did not improve in any metric. The authors conclude that daily training prescription based on HRV could result in a better performance enhancement than a traditional periodization in well-trained cyclists.

Rewire‘s algorithm builds HRV into it’s readiness scores alongside a range of additional subjective and objective measures to provide a holistic approach to readiness. HRV impacts both Rewire’s Overall and Physical readiness score and training recommendations are provided accordingly. Rewire also provides a Personalized Recovery Session that isolates particular weak points in your state and selects a session tailored to your goals for that day. This combination of training and recovery recommendations allows you to perform at your best.

Wrap up

In this blog, we have covered the basics of HRV, and why it matters. We have also provided useful tips and best practices for your morning Readiness Assessment, so that you can collect high-quality data representative of changes in baseline physiological stress, using the Rewire app.

Needless to say, HRV is not the only relevant marker to quantify readiness, and should be integrated with information related to training load as well as subjective metrics such as stress, frustration or muscle soreness, all aspects that might independently indicate potential issues. Rewire offers an integrated approach to readiness that combines all of these parameters to provide you with a comprehensive view of your readiness to train.

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