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Special thanks to Michael and Andrew at the Endurance Innovation Podcast for inviting Marco for a chat. In this podcast, we cover:
Enjoy and stay safe  EPISODE LINK
You can find the episode here. EPISODE NOTES
Special thanks to Pro triathlete Scott Bayvel for inviting Marco for a chat on his YouTube channel. In the video, we cover the following:
Link here. Enjoy  This is the fourth (and last) part of our series of educational posts on heart rate variability (HRV) All you need to know to make effective use of the technology and data is already covered in the previous parts of this guide. However, there are a few misconceptions that keep popping up, and it can be beneficial to try to clarify a few points. In particular, in part 4 we’ll see:
Hopefully, this post will help to clarify most of the doubts you might have, but please feel free to ask questions below should you have any additional points. Full article here. Enjoy the read.  In previous posts, we’ve shown a few examples of what to expect in terms of the relation between HRV and acute stressors (for example traveling, alcohol intake, a hard workout) and longer-term stressors (positive adaptation to training, work stress, poor lifestyle choices, etc.). This part is all about examples and case studies that highlight many of the aspects previously discussed so that you can intuitively see how morning HRV measurements are an effective way to capture changes in stress in response to training and lifestyle stressors. Enjoy!  This is the second part of our series of educational posts on heart rate variability (HRV). In particular, this post is all about how to use the data. We cover:
You can find the full article at this link.  Blog post by Marco Altini Part 4 of our Ultimate Guide to Heart Rate Variability is all about common misconceptions (full post coming soon). In this post, I am covering an important misconception on HRV and subjective data. Misconception 7: HRV is less useful than subjective data to capture how an athlete responds to trainingThis misconception is mostly deriving from a paper that a few years back stated that subjective metrics are better than objective ones in monitoring athlete training response.
But let’s look at what was actually analyzed in the paper. The authors looked at how training load related to both subjective and objective metrics, hence according to the paper, the reference to determine if a metric is a valid metric, is how it correlates to training load. In my opinion, the whole assumption that you should find the metric that “correlates the most” with training load, makes very little sense. Why? Because you are already measuring training load, so what is the point of having another metric that gives you the exact same information? Well, none. By definition, if a metric is perfectly correlated to training load, then it is a useless metric, as it does not add any information to the training and recovery equation (but ironically, it would have been interpreted by the study as the best metric). I’ve already discussed before how the notion that increased load should trigger a reduction in HRV is very simplistic. As a matter of fact, we have seen we can have stable or increased HRV when increasing load (a sign of positive adaptation) as well as reduced HRV with low load because of other stressors (travel, work, etc.). HRV tells you how you are responding and coping with stress, and you can use that information as part of your decision-making process (you can find many case studies here). Finally, don’t get me wrong, it is fairly obvious that subjective metrics are also extremely important. This is why we include a questionnaire after the measurement so that you can take a minute to pause, and self-assess how you are feeling subjectively, a key part of the process. A smart coach, educator or athlete, understands that training load, HRV, and subjective metrics all provide important information that needs to be integrated daily, to decide the better course of action. There is no winner between objective and subjective metrics, they all serve a purpose. Isn't that obvious? Blog post by Marco Altini In this series of posts, I’ll provide an overview of best practices for your Heart Rate Variability (HRV) measurements (part 1), and tips on how to analyze and interpret your data over the short and long term (response to acute stressors, longer-term trends, etc. — in part 2). I’ll include quite a few case studies so that you can clearly see how you can too make use of the data (in part 3). Finally, the last post will cover a few misconceptions (utility with respect to subjective scores, non-training related use, strength training, etc. — part 4). HRV is nothing new, and fairly simple to use effectively, but poor standardization and methodological inconsistencies make it difficult sometimes for people to make good use of the technology or understand what is reported in the scientific literature. Hopefully, these posts will help, but please feel free to ask questions should you have any doubts. You can find part 1 at this link.  LAFC performance director Gavin Benjafield talks about how apps like HRV4Training are giving the team a leg up in its push for MLS Cup glory, check out the article at this link. Huge thank you to Gavin for his words and support of our work, and congratulations on a great season last year  Marco has recorded a podcast with Peter Glassford at the Consummate Athlete. In this episode, they talked about HRV research, and in particular
Enjoy  Case study: physiological stress in response to training (running a marathon) and lifestyle1/17/2020
Blog post by Marco Altini Physiological stress comes from different sources, all having an impact on our ability to deal with additional stress and therefore of maintaining or improving our health and performance. In this post we'll see an example of how a morning measurement of your physiology taken with HRV4Training using the phone's camera, can be a very effective way to capture changes in physiological stress in response to such training and lifestyle stressors. We will also see how the visualizations and analytics available in HRV4Training Pro make it really easy to identify periods of higher stress. In particular, we can see in the image two large drops below normal values, highlighting significant stress on the body:
 “While training prescription is one important part of the physiological puzzle, the other key component is in assessing the ability of the athlete to be able to tolerate training load. With this information at hand, we are able to make informed coaching decisions which will maintain an effective training stress balance. In support of this, we have partnered with HRV4Training to provide this insight and ensure that we remain at the forefront of athlete monitoring, vital to maximising the potential of our nation’s swimmers” Thank you Swim Ireland for your continued support and all the best to coaches and athletes for the upcoming season and the Olympics.  Blog post by Marco Altini As part of my new master's in high-performance coaching at Vrije Universiteit Amsterdam, I had the opportunity to start a research project with the Dutch Triathlon Federation, using HRV4Training to monitor physiological adaptations to a training camp (more on this later, the goal is to publish our research, so I am sure we'll have more to report later during the year). I am really grateful for this opportunity. I found an amazing environment at Dutch triathlon, with knowledgeable and humble coaches and athletes, and I can't wait to keep learning from them and to try to provide a little contribution to their work. Thank you for having me yesterday at the facilities during performance testing, and all the best for the upcoming season.  Check out this post by Ricardo Mazzini, a triathlete from Lima, Peru, currently living and working in Menlo Park, California. Broken wrist, altitude camps, work stress and racing an ironman are some of the main life events that occurred during the year, having a clear impact on Ricardo's physiology. You can find Ricardo's analysis using HRV4Training Pro at this link. "HRV4Training is a great resource to learn more about heart rate variability, and its uses go beyond endurance athletes." Thank you Ricardo and all the best for the new year.  Overwhelmed by the response to our 2020 HRV4Training Ambassador program, we'd like to thank all the athletes and coaches that reached out to support our work. We believe in empowering individuals with the ability to measure and interpret physiological data so that training and lifestyle stressors can be better balanced, resulting in improved health and performance. Learning from athletes and coaches is an invaluable part of the journey Below you can learn more about who they are If you are interested in joining them, you can apply here 
How do you use HRV4Training?I use it everyday before I get out of bed to determine the intensity of my daily training. I have learned how much poor sleep (been fighting insomnia), travel, and diet can affect your HRV and health. The historical data is the 'journal' of my progress. The daily score keeps me from being overambitious. It is my opinion that this is vital for ALL levels of athletes and fitness motivated alike. Just look at my profile pictures...I am proof that it is okay to be okay. I am currently using HRV4Training to prepare for my 10,800 mile charity ride (30 miles a day for 365 days) for The Leukemia & Lymphoma Society this 2020 and will be using it as well to train for the Race Across America (LLS Team). LLS will be helping me promote the event with the hope of getting folks active and aware of their health and health metrics. The dataThe screenshot below shows the past 6 months of Shawn's data. This is taken from HRV4Training Pro, which makes it easier to understand when changes in physiology are significant, as your daily scores and baseline are always contextualized with respect to your historical data (or normal values, the larger band). In the screenshot below we can see my over training and how my body reacted ... poorly. The latter data (last circle) shows that my tapering is helping bring my numbers back up.  In the plot below you can see the same data, but color coded by detected trend. The detected trend in HRV4Training is a combination of resting heart rate, resting HRV, coefficient of variation of your HRV, and training load. We can see how the detected trend captures maladaptation to training, even a bit earlier than training load is reduced, showing how this information could be used to better manage training intensity and training volume, so that we can avoid ending up in a situation of maladaptation to training. You can learn more about these topics at this link.  Anything else you'd like to add?I am not a pro but my goal is to show folks that there is life after cancer.
This week we share a great read put together by Peter Glassford including a few case studies of data collected on athletes he coaches using HRV4Training Pro. You can find the article here. "Heart Rate Variability (HRV) and resting heart rate are great ways to monitor your body and get objective feedback on how your body is handling the training you are putting in. It is important (and valuable) as a gauge of your ‘fitness’ because it also does not discriminate between training stress, work stress, bad sleep stress, or 5 shots of tequila stress! This is a common criticism of TSS or other output measures that are telling you the training stress of your workout but not the stress/strain your body is experiencing from that workout nor from the above lifestyle stressors" The Overview screen in Pro makes it really easy to understand when stress is significantly higher than normal (HRV baseline going below your normal values), and it is probably a good idea in these cases to slow down a little, as shown by recent research on HRV-guided training. Similarly, positive adaptations to increased load (stable or higher baseline) provide additional confidence in the work being done, as Peter shows consistently in the blog post below. This is an important point that is often misunderstood, as you accumulate more training load and get in better shape, your HRV should be stable or increasing, highlighting how you are responding well to your training (despite the high load, this is what positive adaptation is all about!). Thanks Peter and enjoy the read everyone. You can try Pro at https://www.HRV4T.com and use code BIGPICTURE for 10% off *** Peter is a Registered Kinesiologist and Certified Cycling Coach who has been instructing MTB skills since 2000. His coaching clients are mostly busy, masters-aged offroad cyclists who want to optimize their health and performance while balancing family and work. He races Mountain Bikes but dabbles in many other disciplines including BMX, cyclocross, running and triathlon. Peter is also the co-host of The Consummate Athlete Podcast with his wife Molly Hurford. ***  Blog post by Marco Altini I had a great time talking about stress, performance and HRV4Training with Matt Fox of Sweat Elite. You can find the podcast at this link. Matt has spent quite some time in Kenya and Ethiopia as part of his work at Sweat Elite, and provides great insights on the lifestyle of elite athletes training there. We also discuss our own data during marathon training and the combined effect of training and lifestyle stressors on the body. You'll also learn a bit more about how HRV4Training started, recent research on HRV-guided training and the implications of a stressful lifestyle in terms of injury risk and performance. Alright, enjoy the podcast!  In this post, I’d like to show how you can use a simple morning measurement of your resting physiology to gather useful information about your body’s response to training and lifestyle stressors. In particular, we’ll look at two case studies using data from me and Alessandra in the two months leading to the New York City marathon, while dealing with additional non-training related stressors (work, university exams, etc.). We’ll see how stress piles up and how the contribution of training and lifestyle choices has a cumulative impact that is reflected in your body’s physiological state (your HRV). Hopefully, the case studies will be helpful to better understand how you can apply similar principles to your own case so that you can better manage stress towards improved health and performance.  We have just released an improvement in HRV4Training Pro that lets you easily identify periods of significantly higher or lower values in the subjective tags you are tracking with HRV4Training. In particular, the update adds normal values to the plots under the Overview page. The normal values represent the expected value for a certain parameter, given the past two months of historical data. This means that any values outside of this range will be easy to spot (for example days in which you slept much less than normal), and most importantly, you will be able to easily see when your baseline tag (7 days moving average) is outside of your normal values, highlighting how some major change is occurring. Without normal values, it can be difficult to understand if things are just fluctuating in a trivial way, or if there is a larger change that we should be more cautious about. Let's look at a few examples. Below is the data from an athlete that has been prioritizing sleep quality, and we can see that despite some normal variation and a few data points that are particularly high or low (in this case associated to traveling), the baseline never gets outside of normal values, hence confirming that sleep is going well and should not be a major issue or the cause of any significant changes in baseline physiology (e.g. changes in HRV):  Sleep quality is rather stable despite some variability Below is another example where we look at muscle soreness during marathon training, we can see some peaks here and there, followed by periods of recovery as we alternate long and easy runs, as well as the major impact of the race towards the end, and how long it took subjectively to go back to normal:  Muscle soreness during marathon training And finally, here is a complete example where we can look at changes in resting physiology (HRV), training load and subjectively annotate lifestyle stress, during 2 months that include a few business trips (color coded in the first plot), periods of higher lifestyle stress (due to work and traveling, as shown in the last plot), and marathon training (plus marathon day, the peak in acute load towards the end of the second plot). Using the latest visualization in Pro, it is easy to see when lifestyle stress was much higher than normal for this person, and how only the combination of high load (e.g. the marathon) and high stress brought HRV below normal values, showing that we had significant stress on the body (and staying in that condition for several days, with a difficulty to getting back to homeostasis quickly). On the other hand, periods with high stress earlier where managed better, for example by reducing training load:  Overview page in HRV4Training Pro. HRV, training load and lifestyle stress are plotted during marathon preparation (and race day). This case study above shows what we know very well already, stress is cumulative and we cannot isolate training and lifestyle stress or think that training is not affected by everything else going on at any given moment in our professional or personal life.
Yet, a simple marker such as HRV, measured in a well defined context (first thing in the morning while in a rested state), can capture stress deriving from all sources and help us make meaningful adjustments to maintain things in check. We hope you'll enjoy the latest update. If you have an HRV4Training account, you can try Pro for free by logging in here. Blog post by Marco Altini In previous posts we have shown how you can use HRV4Training to read HRV data from the Health app, convert that data (SDNN) to Recovery Points (a more readable metric), and analyze your physiology similarly to what we normally do when you measure using the phone camera or an external Bluetooth sensor. With the release of iOS13 and Watch OS6, Apple provides RR intervals directly in the Health app, which we can use to compute rMSSD, Recovery Points and signal quality, just like we do with the validated camera based measurement or using external sensors. In this post, we'll look at the quality of the data as well as provide instructions for you to use the Apple Watch with our app. Let's start with the practical aspects and then move to data quality. How to use the Apple Watch with HRV4TrainingDue to the fact that RR intervals can only be accessed by apps via the Health app, you need to follow these steps in order to gather meaningful data:
If you do not get your data in Health right after using the Breathe app, try to synch your Apple Watch and it will show up a few seconds afterwards. Always remember that context is key, so while the Apple Watch writes somewhat random HRV numbers also during the day or night, that data could be affected by artifacts, and it is always decontextualized. To properly interpret physiology, data must be acquired under standard, reproducible conditions, and the best way to do so is with a measurement as soon as you wake up, or with a night long measurement (not just a minute or two over a night). Only in this way, you'll be able to determine how you are responding and adapting to training and lifestyle stressors, as shown in this post and in this case study. If you have used already HRV4Training with your Apple Watch, then you do not have to do anything different, but we will be able to provide you with a better analysis of your parasympathetic activity, as we can now compute directly the rMSSD feature and Recovery Points, instead of estimating it from SDNN. Comparison with chest strapsData was acquired using the Apple Watch and a Polar H7 (previously validated with respect to ECG here) connected to a different device running the HRV Logger app, which is an app that simply records everything coming from the sensor plus additional features. During data acquisition, we collected data a few minutes while breathing freely, and a few minutes while deep breathing, to elicitate higher HRV due to RSA. You will see in the plots below visually the effect of deep breathing as we get greater swings in RR intervals. Then, we built a simple app to read the Apple Watch RR intervals from Health, so that we could compare them to what we collected with the Polar chest strap. A final note on data synchronization: data cannot be perfectly synchronized because it is not timestamped by the sensors. What we can do is either to log real time and then to split data in windows based on when data was collected, then compute HRV features on these windows or to sum up RR intervals over time. For this analysis we went with the second option and also tried to visually align the data streams.  What can we derive from these data? You can see clearly almost perfect correlation between Polar H7 and Apple Watch for all conditions (relaxed vs paced breathing as highlighted by bigger oscillations in RR intervals or instantaneous heart rate), meaning that the sensor works really well in this modality. Heart rate variability: rMSSDAs features, we will look only at rMSSD, the only feature we really care about. rMSSD is a clear marker of parasympathetic activity and the main feature we use for our analysis in HRV4Training, similarly to what other apps do as well. Additionally, the sports science community seems to have settled on this feature for several reasons (apart from the clear physiological link, as mathematically it captures fast changes that are due to how the vagus nerve modulates heart rhythm, there are also practical implications, as it is easy to acquire, easy to compute and reliable over short time windows and less controlled conditions), and therefore we'll stick to it. What we expect given the data above is to see extremely close values between the Polar H7 chest strap and Apple Watch data. For the plot below, I computed rMSSD for each time window:  Results are very good considering normal variation in physiology and limitations in data synchronization. FAQWhat are Recovery Points? A more human friendly HRV score, based on rMSSD. For more information, read this. How accurate is the Apple Watch in measuring HRV? Very accurate, provided you stay completely still and use the Breathe app to take a measurement. When should I use the Breathe app to take a measurement? First thing in the morning. How much time do I have after measuring with the Breathe app, to fill in my tags in HRV4Training? You have three hours. When you tap 'read from Health' we always check only the last three hours, and see if we can find any HRV scores in the Health app, then take the last one. For this reason, we highly recommend reading data right after you have measured. Should I use the Watch or the camera? Up to you. We consider both methods equivalent, and it is entirely based on your preference that you should make the call. What matters the most is that you are consistent over time, hence simply use what you consider the easiest and most practical method for you. Useful resourcesCollecting high quality data is always the first step, but of course what we want to do is to make meaningful adjustments using that data. How do you do that? Here are some links that can help understanding the relation between physiology, training and lifestyle stressors:
HRV4Training is looking for brand ambassadors worldwide! Are you passionate about sport and technology and have been using HRV4Training daily to better manage stress and improve your performance? We are looking for you! We believe in empowering individuals with the ability to measure and interpret physiological data so that training and lifestyle stressors can be better balanced, resulting in improved health and performance. Learning from athletes and coaches is an invaluable part of the journey, and we are looking forward to getting to know you and your experience. What do we expect from ambassadors?
What do we offer to ambassadors?
How do you Apply?
Deadline is October 31st!  Blog post by Marco Altini In this post, I’d like to show how we can monitor progress (or lack thereof) in endurance sports using tools such as aerobic efficiency and cardiac decoupling analysis in HRV4Training Pro. I will also show how training adaptations resulting from different training stimuli can be captured by these tools better than using standard training load analysis metrics such as chronic training load. I hope you'll find it helpful.   Blog post by Marco Altini Just a quick announcement that all new iPhones are already compatible with HRV4Training, you can see a short video on an iPhone 11 here on our instagram. As you know the new iPhone has 3 cameras, hence some changes were required. In particular, you will need to use the camera in the corner, as shown here:
As usual, please double check our camera based measurement best practices, to make sure you'll collect high quality data on which meaningful analytics can be derived. Below you can also see two minutes of RR intervals data collected with the phone and a Polar chest strap, showing the usual agreement between the two, as reported in earlier validation studies. Enjoy!  Useful resourcesCollecting high quality data is always the first step, but of course what we want to do is to make meaningful adjustments using that data. How do you do that? Here are some links that can help understanding the relation between physiology, training and lifestyle stressors:
In this post we highlight a small update we implemented to make it easier for coaches and teams to monitor HRV trends. In particular, we have seen from published literature how 3 to 5 measurements per week can be sufficient to monitor an athlete baseline, and similarly we have seen from practical experience that many teams prefer to measure in the 3-4 days in the middle of the week, far from games (for a more comprehensive overview of these aspects, check out this blog post). Yet, lack of daily measurements makes it more difficult for coaches to get a quick overview of the team status in HRV4Training Pro, as some data might be missing. See for example the panel below where we have missing data for one athlete:  Some of the professional teams we work with do their research, and they know well that the important bit is to look at baseline changes with respect to normal values, as covered here and also in state of the art interventions showing improved performance when following HRV-based advice (see an overview here). Hence, lack of a daily measurement should not be a problem, we could for example use the athlete's past week of data, compare to her or his normal values, and then show feedback based on the comparison between HRV baseline and normal values. This is exactly what you can do by enabling the "Force HRV advice" in your Coach Panel:  At this point you will be able to get visual feedback on the missing athlete's HRV trend:  Which can of course be confirmed by opening the Overview page and looking at the data, in case you'd like to dig deeper:  We hope you will find this addition useful to keep track of your team physiological data efficiently and effectively.
Enjoy Blog post by Marco Altini We have released a new feature in HRV4Training Pro: Training Monotony. In case you want to jump right in, and check out our latest feature, simply login at HRV4T.com with your HRV4Training credentials, then navigate to Insights / Training Load Analysis As a coach, you can access these estimates for all your athletes from the Coach Panel.  Overview of the Training Load Analysis in HRV4Training Pro. What is it?Training monotony refers to the similarity of daily training. In practical terms, this is a statistical representation of how much your training stimulus is varying over time. As in all other analysis included under our training load analysis, the first thing to do is to pick a training load metric, or training impulse. This can be relative effort, TSS, RPE, RPE x Duration or any other parameter that is relevant in your sport. Once you have picked this parameter, HRV4Training Pro will analyze on a weekly basis, to determine training monotony.  Freshness, injury risk and monotony are computed from training impulse and can be representative of different processes. Freshness is about recovery and being race ready, injury risk compares your recent and habitual load to determine if you have increased load too much with respect to what you are used to, and therefore increased injury risk. Monotony concerns variation in training, with the idea that optimal performance is associated to higher variation. How do you use it?In general, low monotony (a value below 1.5 for example) is preferable so that different training adaptations can be triggered, while allowing for sufficient recovery to the body. Low monotony is normally associated to a polarized training and other periodization methods alternating high and low intensity workouts. On the other hand, a high value for training monotony indicates that the training program might be ineffective and lead to stagnation, or lack of improvement. Hence, if your score tends to be higher, it might be time to try something different. Here is for example a month of workouts of varying intensity and duration, resulting in very different relative efforts (the training impulse metric available in Strava and used for this example):  You can see how training monotony is indeed very low:  On the other hand here we have a week with very similar workouts (second row in particular):  Which corresponds to the yellow spike in monotony below, an indication that the stimulus recently has been always quite similar on a day to day basis, which might be unproductive for performance:  Needless to say, this is an oversimplification of the many processes affecting human performance. However, several authors have found that lower monotony is linked to higher performance, and therefore we hope this extra data point that can be informative and help you critically analyze your progress. Alright, that's all for this update. Enjoy. Useful resources:
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Blog Index The Ultimate Guide to HRV 1: Measurement setup 2: Interpreting your data 3: Case studies and practical examples How To 1. Intro to HRV 2. How to use HRV, the basics 3. HRV guided training 4. The big picture 5. HRV and training load 6. HRV, strength & power 7. Overview in HRV4Training Pro 8. HRV in team sports HRV Measurements Best Practices 1. Context & Time of the Day 2. Duration 3. Paced breathing 4. Orthostatic Test 5. Slides HRV overview 6. Normal values and historical data Data Analysis 1a. Acute Changes in HRV (individual level) 1b. Acute Changes in HRV (population level) 1c. Acute Changes in HRV & measurement consistency 1d. Acute Changes in HRV in endurance and power sports 2a. Interpreting HRV Trends 2b. HRV Baseline Trends & CV 3. Tags & Correlations 4. Ectopic beats & motion artifacts 5. HRV4Training Insights 6. HRV4Training & Sports Science 7. HRV & fitness / training load 8. HRV & performance 9. VO2max models 10. Repeated HRV measurements 11. VO2max and performance 12. HR, HRV and performance 13. Training intensity & performance 14. Publication: VO2max & running performance 15. Estimating running performance 16. Coefficient of Variation 17. More on CV and the big picture 18. Case study marathon training 19. Case study injury and lifestyle stress 20. HRV and menstrual cycle 21. Cardiac decoupling 22. FTP, lactate threshold, half and full marathon time estimates 23. Training Monotony Camera & Sensors 1. ECG vs Polar & Mio Alpha 2a. Camera vs Polar 2b. Camera vs Polar iOS10 2c. iPhone 7+ vs Polar 2d. Comparison of PPG sensors 3. Camera measurement guidelines 4. Validation paper 5. Android camera vs Chest strap 6. Scosche Rhythm24 7. Apple Watch 8. CorSense 9. Samsung Galaxy App Features 1. Features and Recovery Points 2. Daily advice 3. HRV4Training insights 4. Sleep tracking 5. Training load analysis 6a. Integration with Strava 6b. Integration with TrainingPeaks 6c. Integration with SportTracks 6d. Integration with Genetrainer 6e. Integration with Apple Health 6f. Integration with Todays Plan 7. Acute HRV changes by sport 8. Remote tags in HRV4T Coach 9. VO2max Estimation 10. Acute stressors analysis 11. Training Polarization 12. Lactate Threshold Estimation 13. Functional Threshold Power(FTP) Estimation for cyclists 14. Aerobic Endurance analysis 15. Intervals Analysis 16. Training Planning 17. Integration with Oura 18. Aerobic efficiency and cardiac decoupling Other 1. HRV normal values 2. HRV normalization by HR 3. HRV 101 |
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