By Carl Valle
Heart Rate Variability (HRV) isn’t new, but it’s evolving to the point that many coaches now use HRV in their training. I have used HRV monitoring for 10 years, but only really adopted it as a true part of training when the iPhone made acquiring the heart signal efficient and cost-effective. Five years later, I have gleaned a lot of information on the way athletes respond to training, and I find the use of the ithlete indispensable for the modern athlete.
In this article, I focus on the simple but sometimes challenging process of collecting measurements daily. It doesn’t matter if you work with one athlete, 100 athletes, or more, the same rules apply when sampling an athlete’s autonomic nervous system.
What HRV Really Means to a Coach
I can bore you to death by rehashing science you already know, don’t want to know, or might not need to cover in detail, but I won’t. HRV is a measure of the heart rhythm between beats, and that information is scientifically supported as a valid indication of fatigue or change in autonomic status. Coaches use HRV as one clue to let them know how athletes are adapting or failing to adapt to training loads.
HRV summarizes a lot of inputs into the body, so HRV is more of a total body response than a specific indication of what is going on in the body. Still, HRV is a great metric to keep coaches aware of what is going on below the surface, and the scores make application an easy process. Without diluting HRV too much, it’s a practical way to address recovery for coaches who need objective readiness information.HRV is a great metric to keep coaches aware of what is going on below the surface. Click To Tweet
Several smart people have explained about interpretation and usage in the field, so I will get into the most important make-or-break part of monitoring HRV—the sampling. No matter how good you are at breaking down statistics, HRV does have a few caveats with measuring the heart signal. HRV measurements done haphazardly, or with good intentions but poor reliability, will compromise the entire process. Athletes who actually want to take advantage of the data and are compliant may sabotage or taint the data if they don’t follow directions or stress out during testing.
If you can collect data efficiently and properly, HRV can change lives and reduce headaches. On the other hand, if you skip or rush the process, it will backfire and create more problems than it solves. This article has one promise: It will outline whether HRV is right for you, and show you how to honestly collect the data.
What Is Required for a Valid Assessment of HRV?
This article covers the minimal requirements to get a data point that is valid for users of the ithlete system, but some overlap exists with any physiological monitoring device, like Omegawave or Firstbeat. I have used ithlete since it was first available at the Apple store, and was amazed how solid the data was compared to far more cumbersome lab assessments. My first struggle was in the mid-2000s, when I was using Polar and an open source program for the laptop, and gave up on it as a daily tool. Coaches need a balance that is both scientific and realistic. Coaches’ labs are weight rooms and athletic fields, so something that is fine for a research publication may not be repeatable with athletes who tend to complicate things!
Here are five elements that I believe improve the integrity of the data collected.
The athletes you work with have to do two things well—follow directions and be honest with the process. If athletes can relax and comply with your selected protocol, the process takes less than two minutes, total. Two minutes every day is the typical bandwidth for monitoring, and anything beyond that isn’t realistic.
- Repeatable Protocol – A few acceptable techniques exist in HRV sampling, and Andrew Flatt and Simon Wegerif shared the details of paced breathing and supine versus standing options. Ultra-short readings of 60 seconds, following an HR stabilization period, demonstrate enough repeatability in the literature. As long as the setup removes possible interference with randomness, an athlete on a good routine can get great data from unconventional protocols. Simplicity and clarity rule supreme here, such as testing first thing after an athlete wakes up or 30 minutes after their arrival at the training facility.
- Resting or Relaxed State – One minute is a short period of time, but to the modern athlete it can seem like eternity. While athletes that might be adrenaline junkies and lack the patience or discipline to calmly collect data are those that could benefit the most from HRV sampling, they are least likely to gravitate early to it. Coaches and everyday people need mindfulness training, and I prefer athletes to stand with their phone on their dresser and hold the wall for a minute of breathing patterns with closed eyes or a relaxed gaze. I can’t convince an athlete to take up yoga or extensive dedication to a Zen lifestyle, but I can get a few, small mind “tune-up” sessions and daily HRV. A random song on Pandora adds a nice extra to the boring process of breathing.
The HRV monitoring product begins where the responsibility of the athlete ends. You pay for the hardware and software, and the methodology of using the product comes from sport science and the power users that sometimes help consult with teams to utilize it better. The weakest area in the performance world is methodology, as too few practitioners have both the coaching talent and the experience with this type of data to really make a difference. Consultants are usually former or current coaches who committed to the process and add value to the ecosystem.
- Precise and Accurate Hardware – I have acquired autonomic data from various organ systems and different hardware options, but one key thing to know is that HRV is non-invasive, so it requires proper placement and some anatomical knowledge. Many watches have failed to live up to expectations, so when convenience is presented, make sure no compromises are made. Take the Apple Watch, for example. If major companies are unable to capture HRV without a few problems, limits exist with options that are not directly measuring the heart. Photoplethysmography with a fingertip sensor is a validated approach to capturing HRV and, while smartphone cameras are likely the future, they do have noted issues with artifacts.
- Statistical Analysis – In order to take the heart signal and convert it to a score that is easy to utilize, some serious math needs to be done. I could get into more detail, but some indices have mathematical significance that is not biological significance. The research usually uses standards that the scientific community agrees with, but how that statistical significance relates to clinical matters is still up in the air. I understand innovation sometimes has intellectual property issues that make transparency difficult, but after a few years the black box needs to be opened up to the teams and coaches who need to evaluate the product. ithlete has demonstrated high fidelity here with their published studies.
- Research Vetted Score – When the numbers from the processing of the signal and analyzing period are done, the standardized data that sport science is comfortable with moves to a gray area that is product specific. To differentiate, many systems have more features or benefits beyond the vanilla science that is available. The problem with features is that they need to be proven to work, not just proven to sell.
The entire system should be validated or the process openly shared for review as much as possible. Test driving the product is a great start, and necessary white papers with cited references can help support the positioning on the way a product functions. Of course, methodology and what you do with the information comes later, but now, as you’re being educated on the HRV reading process, it’s worth noting how the scores are created.
One part of the process that’s not mentioned is the wellness questionnaire (or subjective indicators), along with a dialogue box for short logging. I find that subjective and objective data work in harmony, even if the data doesn’t align or agree. The better the compliance or engagement, the more likely the information will be valuable. One area that is golden is the short notes area, which can be combed over a year later to make a very compelling timeline of the reasons that HRV is fluctuating.Data recorded in the short notes area can build a compelling account of HRV fluctuations over time. Click To Tweet
When to Test HRV During the Day
Coaches have three options when testing HRV as a marker of autonomic readiness, and each has its pros and cons. Some programs test continuously and multiple times a day, but even just getting a one-minute sample a few times a week is a great win for programs that are unsupported by their organization. Each option has pros and cons, meaning a benefit in capturing HRV at the facility instead of an athlete’s home reduces athlete compliance issues with some teams. However, the data will be prone to interpretation problems, as the process is not as clean with variables after someone wakes up, like breakfast, driving, and social interaction. Testing athletes post warm-up is also a benefit with youth sports, but isn’t easy to sustain over a season.
Morning Wake Assessment – My favorite option is to test athletes using their smartphones with a simple strap or finger sensor after they wake up. The reason I love this method is that it forces the athlete to start the day with an effective communication process, beginning with core vitals and a light wellness questionnaire. The sample of HRV lasts a minute, and a half dozen questions and space for notes is the perfect amount of interaction for millennial athletes who struggle to follow through with tasks that are not instant.
When you test first thing in the morning, it’s a time stamp to getting out of bed, a time right after waking, or ceasing the rest and sleep period. Testing right after sleep is a period of seclusion from the outside world, thus removing impactful variables that could cloud the reading. Finally, getting the data earlier gives coaches time to prepare for any surprises or necessary adjustments.
Facility Team Assessment – Another popular and validated option is testing a batch of athletes or each athlete as soon as they arrive. I have witnessed success with this, as professional clubs don’t like to leave things to chance. Testing a group or entire roster is possible, and if you feel that it’s the right mode for collecting data, you can get a lot of solid information from this process. Nearly every research study uses an internal process, so while a little compromise exists, it’s fine for most circumstances. One factor to consider is the need for large areas for athletes to lay down in and relax.
Post-Warmup Assessment – The narrow window from after a warmup to the main workout is a tough, but still viable, time to get some useful measure of readiness. The issue I see with this from a coaching perspective is that, outside of team heart rate options, it’s not easy to administer in a practical manner. I have done this a few times to see how conditioning tests might be trending, or to screen out those that are overloaded, but I have never had success. I think this may work for youth athletes like the Buchheit presentation years ago, but it’s not something I would suggest as a standalone assessment. To me, it’s a great way to see information added to a morning or facility test, but making choices and decisions on the fly is too difficult, even with an anticipated decision tree.
If you are trying to get a sustainable process in place, go with the option of testing right after wake or right after the athletes arrive. Additional information can be collected during the warmup, but keeping the process repeatable with athletes in collision sports is, for the most part, not happening. Choose what works for you and know the advantages and conveniences of what you decide to use, as well as the problems and interpretation limits.
How to Improve the Daily Sampling Process
The meat of this article deals with the collection side and shares some important ways to reinforce a sustainable sampling of HRV. If you want HRV monitoring to resonate with athletes, don’t talk about the autonomic nervous system or vagal tone. Coaches can talk to athletes about HRV, but use Rest score or something similar. Over time, some athletes will be able to use the term “HRV,” but heart rate usually dilutes the value of the information. Some coaches use vitality or something similar, because readiness will spook athletes who score poorly on game day. Language is the first step to getting athletes to connect with the monitoring of their training and recovery. Too much slang creates vagueness and clarity issues, but something right in the middle of teenage pop vernacular and science fiction works.To get athletes to monitor their training & recovery, be aware of language choice. Click To Tweet
After language comes reinforcement of choices in training and recovery due to the scores. The knowledge that you consistently and frequently make serious or important decisions based on the data will improve athlete compliance. A lack of data will also help you, especially when athletes see their teammates benefiting from the information while they get guessing games. Some coaches actually add more personalization to the workouts of athletes that provide HRV, to reward them. Athletes who don’t provide data have no valid argument for not getting the “good workouts,” so it makes them the bad guy and not the coach playing favorites.
Finally, learn from salesmen and make the process a journey. If Steve Jobs was still alive and had to sell HRV monitoring at the end of his keynote presentation, he would find a way to make the most ordinary part of sport science into a magical experience. When selling HRV to athletes, I often explain to them that it’s like a samurai warrior in the garden getting ready for battle with meditation. Find something that connects and, in time, they will appreciate it without the parlor tricks. You have to get someone to have blind faith in the process quickly, and this comes from real team “culture” or tribe building.
What to Do When Athletes Screw Things Up
Some leagues and teams allow athletes to “run the asylum” and plenty of athletes “just want to play ball.” What happens is that some athletes become rebels, showing up late for assessment while holding an energy drink to try to fix their lack of sleep and garbage dedication to nutrition. Some athletes are less bold but still lazy, and just give up if something isn’t spoon fed to them. My experience is that motivation precedes education, as explaining someone the science or value isn’t going to work unless you tap into their mindset.
Several coaches talk about building trust, but what about the rookie or freshman athlete on Day One? What’s trust—which is built slowly over time—going to do about collecting weird data they don’t care about? Monitoring is sometimes annoying, and I always point out that while nobody expects other professions (like lawyers) to do wellness questionnaires to reduce burnout, times are changing. Wearables are the new normal, but a consumer electing to buy a device is not the same as an athlete being forced into something without a choice. Not all athletes can be tamed, so this is how I handle a range of dedication and attitudes.
As the athlete becomes more elite, they tend to rule the roost with what they want to do, so embrace that pattern and don’t fight it. Some colleges are stricter and enable the coach to call the shots, so while an athlete might be responsible for their data collection in some way, they are likely to do the absolute minimum to the point of being stubborn as a mule. Sensors will get lost or broken. Apps will crash, batteries will die, and Bluetooth will fail to connect properly after mysterious OS updates. Other athletes (usually the less talented ones) seem to always get their technology to work, while the mustang athletes are busy and have excuses. When an athlete drags their feet on monitoring or refuses to engage with the process, be calm, firm, and professional.
Talented competitors in sport want to play well, and for as long as they enjoy the game. Some athletes are talented but have no love of the sport, but they are smart enough to realize it’s a business that has benefits, so they will do just enough to get by. The sad reality is some athletes may never, ever buy in. Don’t give up on them, as those that don’t comply teach you how to convert the less extreme athlete. One former NHL coach explained that some athletes will do anything for the coach, some will always be jerks, and the majority will do it if it’s not a burden.
The key is making HRV a clear benefit to them in the short term through instant gratification, while at the same time getting them to value the longitudinal trail they get when they put in a little commitment over time. Lame gamification techniques work for a few weeks and then become a novelty when the athletes with poor dedication become negative toward them. Athletes must be rewarded with a very small amount of gratitude for collecting the data. Explain how you will make better decisions about their workouts, and provide a direct way to improve that score that benefits them immediately.
When athletes are compliant with interventions and their scores don’t reflect their efforts, it’s not an easy pill to swallow for everyone involved, but don’t despair. Winning examples from others will be enough ammunition to keep athletes committed. Just like training, monitoring may not show up acutely as a benefit, but if you can show them you use it to help them with support services that they understand, the athlete will connect HRV with benefits instead of arbitrarily measuring the body. If you only get one takeaway from this article, I’d like it to be the notion of the athlete having an understanding that HRV is used daily and is valuable in helping them immediately.Athletes need to understand that HRV is used daily, and is valuable in helping them immediately. Click To Tweet
Don’t try to sell athletes or convince them to buy in—connect to what they already believe in or bought previously. Finally, seek progress, not perfection. Looking at a completely filled-in chart for each athlete being compliant is emotionally rewarding but not likely to happen, so focus on moving the needle and not having perfect adoption.
Tailoring the Process to Your Environment
Even if only one athlete on an NBA basketball team is willing to do an honest job with HRV, remember that there was a time when strength and conditioning coaches didn’t even exist in the league. Even if you can only do it for yourself today, in time curiosity will rub off and athletes will want to know how to get an advantage to win. Some coaches will have a dramatically different situation, with athletes who demand support, but this is usually in Olympic and endurance sports, which require training to be on point in order to compete. Most programs will be in the middle, which means athletes will do a decent job and it’s up to the coach to remove as many barriers and friction points to get data and show its value early.