Heart Rate Variability (HRV): A New Tool for Exercise Performance?

Health Writer

If you’re a fitness enthusiast who likes to use trackers, then the latest technology may take your exercise efforts to the next level. Zoom HRV is one of the newer heart rate tracking wearable devices that offers a range of performance and sleep variables, including heart rate variability or HRV.

Serious exercisers often use heart rate recovery measurements to track performance improvements. Typically, you start to exercise and push yourself until you are working out at the highest heart rate you can sustain. You log your pulse at that point, and then reduce the resistance.

After 60 seconds, you take your heart rate again. The difference between your heart rate “high” and the number of beats after one minute indicate recovery and the “larger the difference,” the faster the recovery. For example, if maximal heart rate is 160, and after one minute your heart rate drops to 130, then your heart beat decreased by “30.”

Exercisers want to improve recovery, meaning continue to see an even “bigger difference” between the two heart rate measurements, which would signify strengthening cardiac muscle and performance gains.

But wouldn’t you like to know when you wake up in the morning, if you are in optimal shape for the training session you have planned for that day? In the case of sports enthusiasts and professional athletes, that information would be incredibly valuable.

It would allow you to engage in more vigorous exercise workouts on days you knew you could have optimal performance. It would also clue you to scale back your workout, if your body was somehow under stress (poor sleep or recovery), and less likely to meet the demands of a strenuous workout.

HRV has been considered a relevant marker in helping to predict sudden cardiac death and in assessing heart-based and metabolic disease progression. It is also used as one computational parameter in diabetic neuropathy, depression, and predictability of sudden infant death syndrome or SIDS.

Computing HRV is complicated, involving EKG monitoring and complex formulas and calculations. More recently the fitness world has begun to use it as a tool for assessing and identifying optimal training loads for athletes in order to achieve optimal performance. Still according to current research, there is much more to be learned about HRV and how to apply it to sports physiology.

So what exactly is HRV?

Mike Hosey, president of LifeTrak offered a basic explanation, suggesting that when you take your pulse, in beats per minute, you assume that the time elapse from beat-to-beat (R-R interval or inter-beat interval) is precise and equal. That’s not always the case. In fact, there can be levels of variability between beats. Whether there is more or less variability, beat-to-beat is linked to stress and the impact stress has on your autonomic nervous system and in this case, the heart muscle.

Through precise testing, models and very complicated formulas, it has been determined that “the more variability between beats,” the more optimal your exercise effort will be. The Zoom HRV tracker captures data including continuous heartbeat, hours/depth/quality of sleep, calories burned (based on heart rate intensity), laps in pool, steps on a trail or RPMs on a bike, and HRV. It specifically captures HRV while you sleep (Vscore) by creating a graph that you sync from the tracker to the app, after a full night’s sleep.

You can also do a two minute manual capture of HRV (Vscan). The Vscore will tell you if you are sufficiently recovered (higher is better) to face a challenging workout. Finally, the device also has a built in light tracking feature, which makes real-time recommendations so that you get proper exposure to the type of light rays that appropriately stimulate natural melatonin production.

__The Zoom pairs with its own app but you can also use smartphone technology to review and access data. As with many of the new trackers, it typically holds a charge for five days. You can wear the tracker on your wrist, upper arm, or even your ankle (unique to this tracker), and it does not require wearing a chest strap to capture heart rate activity. __

The device does require you to spend quite a bit of time reviewing the extensive manual, if you want to really understand all the features, and as with most devices, the more you use it, the more proficient you will become at utilizing all the data capture features. Millennials and tech geeks will likely find the device more user-friendly than the average consumer who might find the feature set too complicated.

You do need to remember different numbers of “clicks” to engage with different features, since there is only one center button that accesses different readings and data. Hosey confirmed that the app is still being updated and refined, as the company strives to work out certain kinks and make the device more intuitive and user-friendly.

Zoom’s parent company, Solutron, Inc., has been involved in research and development projects for NASA, the EPA, the DOL and other government agencies. Solutron is also the originator of pulse reading technology on most commercial exercise equipment. The ZoomHRV, priced at $139.99, is currently being used by some sports teams and athletic groups. Zoom currently does not have enough published data to attest to the device’s accuracy.

Companies like ithlete capture and use HRV captured data by interfacing its app on a smartphone with a heart-rate monitor chest strap.

A quick mention of a less sophisticated tracker, the Mio Slice ($129.00) is appropriate, because it focuses more on a health score called Personal Activity Intelligence or PAI. According to the company, “PAI is a scientifically validated activity metric based on heart rate and personal data that provides users with a simple score/universal goal: keep your weekly PAI score at or above 100 (over seven days) to maintain optimal health.”

The tracker, worn on the wrist, offers readily available heart rate readings (the Zoom requires you to access the readings on your smartphone). The researcher who developed PAI found that individuals who regularly exercise, and meet certain fitness milestones and weekly PAI of 100 (or higher), are shown to live longer, healthier lives. This type of tracker may be a great motivational tool for exercise beginners, or consumers looking for a less complicated goal. More fit individuals who exercise daily may hit PAI scores well above 100.

Two important notes:

Previous studies have shown that tracker devices do not necessarily improve weight loss efforts. Trackers may help to keep some individuals motivated to exercise more frequently and it provides somewhat objective data. It’s important to realize that a pedometer tracks steps by monitoring hip motion. You can skew the data by moving your hips when you stand still. The newer trackers use arm motion to calculate steps, laps or other exercise activity, so if you’re on a step machine or elliptical, the devices will not capture precise, if any motion, since arm movement is usually limited.

Efforts to connect with several cardiologists to get a viewpoint on HRV as a sports performance tool, responses alluded to a lack of personal experience with the concept and robust published research on the subject. This suggests that the tool is still in need of more research and vetting specifically as it relates to “use in sports performance for enhanced outcomes.”

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Amy Hendel, also known as The HealthGal, is a Physician Assistant, nutritionist and fitness expert. As a health media personality, she's been reporting and blogging on lifestyle issues and health news for over 20 years. Author of The 4 Habits of Healthy Families, her website offers daily health reports, links to her blogs, and a library of lifestyle video segments.