Heart Rate Variability Training (HRV) for Cardio Fitness
It is common knowledge that trained athletes have lower resting heart rate. Now we know that higher Heart Rate Variability (or HRV) is also an indication of good general fitness.
HRV used to only be accessible in hospitals and used as a predictor of cardiac arrest. Nowadays, we see the topic of heart rate variability popping up more and more in fitness circles.
Let’s see what the hype is all about and how measuring your HRV can be used to take your own cardio training to the next level.
What is HRV and How Does it Work?
Heart rate variability is associated with autonomic nervous system. HRV refers to variation between heart beats over time, meaning that the heart does not beat regularly.
Trained athletes usually have higher HRV and it usually indicates better adaptation to physical stress and domination of parasympathetic (“rest and digest”) nervous system, whereas lower HRV would show domination of sympathetic (“fight or flight”) nervous system.
It is important to note, that one HRV reading is not a good indicator of dominant nervous system, because our lives vary on day-to-day basis. Therefore, it’s crucial to establish baseline HRV measurements and refer to HRV trends when analyzing your nervous system dominance.
There are two most common ways to measure HRV, that is R-R intervals obtained using electrocardiogram and inter-beat-intervals (IBIs), measured with photoplethysmography (PPG). HRV measurements are usually calculated with rMSSD (Root Mean Square of the Successive Differences) formula. Other popular HRV metrics include HFP (High-Frequency Power) that indicates parasympathetic nervous system domination and LFP (Low-Frequency Power).
Sounds complicated? Fortunately, you don’t have to do any of those calculations yourself, most apps and wearable trackers on the market do it for you.
How to Use HRV for Training
The application of HRV that most people are interested in is tracking physical training adaptation. HRV readings have been used to assess physical readiness and recovery of athletes.
More and more high-level competitors incorporate HRV readings to their daily routine. The study published in the European Journal of Applied Physiology took twenty-sex moderately fit males and assigned a 4-week training routine.
HRV-guided training group received individual training program based on individual changes of their HRV. Increase or no change in HRV led to a high-intensity session. If there was a significant drop in HRV or decreasing trend for 2 days, low-intensity session or rest was prescribed.
The study concluded that cardiorespiratory fitness can be improved effectively by using HRV for daily training prescription.
Another study, that appeared in the journal of Experimental and Therapeutic Medicine concluded that HRV is a useful non-invasive method to track physiological changes following physical activity.
Based on these and other studies, I see the benefits of tracking your HRV and I have been measuring my HRV for 5 minutes first thing in the morning and it has really helped me to opt for “lighter” days when my body needs them. Ultimately, I get high ROI on my workouts and can maintain good results with the minimum effective dose of training!
 Eur J Appl Physiol. 2007 Dec;101(6):743-51. Epub 2007 Sep 12.
 “The role of heart rate variability in sports physiology” Experimental and therapeutic medicine vol. 11,5 (2016): 1531-1536.
Other Uses for Measuring Heart Rate Variability
Aside from the clinical application, HRV monitoring has also been pretty popular for meditation. A company called HeartMath is using HRV to guide your breathing and give you instant feedback on how to calm down your sympathetic nervous system. This technique has been well liked among high-profile executives and growing in popularity in the athletic community.
How to Track HRV During Workouts
Nowadays, there are plenty of wearables on the market that are able to track HRV.
Personally, I currently use the combination of Polar H10 hear rate monitoring strap and Elite HRV application. It takes 5-minutes first thing in the morning to calculate my “morning readiness”.
I am also a huge fan of the Oura ring – the ultimate tracking device that is incredibly small and is perfect for self-quantification geeks like myself. It isn't a cheap device but it not only tracks your HRV, sleep patterns and body temperature, but also helps you determine your circadian rhythm.
Whoop is another great company on the map that works with NFL players, CEOs, Navy SEALs and Olympians. They help athletes and their coaches track their performance and personalize their workouts.
To sum it up, technology is taking over the athletic world and HRV is one of the easiest, non-invasive methods to help you out. Let’s not forget that everyone is different and the key to tracking heart rate variability is establishing baseline HRV and focusing on its tendencies rather than comparing your HRV to others.
I highly recommend implementing it into your own training.