Regular Mark’s Daily Apple readers know of my enthusiasm for the cutting edge biofeedback technology known as heart rate variability (HRV). There is a detailed introductory post here, and a follow up post here. In short, HRV measures the variation in beat-to-beat intervals of your heart, providing a direct window into the functional state of your autonomic nervous system. A high HRV score (indicative of more variation in beat to beat intervals) suggests a synchronistic balance between your parasympathetic (“rest and digest”) nervous system and your sympathetic (“fight or flight”) nervous system. A lower than normal (for the individual) HRV score is indicative of sympathetic dominance—a state of overstress or poor cardiovascular function.
While resting heart rate has long been the gold standard to measure an athlete’s general state of stress and recovery, HRV takes biofeedback to the next level by delivering more nuanced readings that accurately reveal conditions like hyper-arousal or burnout. This is critical because when you are under the influence of fight or flight hormones (as in, most of the time in hectic modern life), it’s difficult to tell when you are overstressed and heading for burnout.
The more you study the intricacies of HRV, the more interesting it gets. Some experts claim that deliberate breathing practices can elevate HRV—meaning that you can be alerted to and learn to regain sympathetic/parasympathetic balance when things get hectic. Serious athletes use HRV to govern training decisions—ensuring they are fully recovered before attempting breakthrough workouts, or undergoing forced rest periods (even when they feel fine subjectively) when HRV readings are suppressed.
I’m so enthusiastic about promoting the concept of HRV that I partnered with the industry leaders at Sweetbeat Life LLC to create a customized iPhone app called PrimalBeat HRV. You can purchase PrimalBeat HRV for $10 at the App Store (sorry, no Android version yet, coming soon…) and get started with daily HRV monitoring on your iPhone, iPad, or iPod Touch. Of course, you will also need a Bluetooth (ideally Bluetooth Low Energy (BLE 4.0)) enabled chest strap to pair with your iPhone. If not, you can grab a Polar H7 strap for 50 bucks on Amazon. I mention Polar since they have been the leading heart rate monitor brand for decades, but other great products like the Wahoo chest strap (60 bucks on Amazon) and any other Bluetooth enabled chest strap will sync with your PrimalBeat HRV app.
It’s important to take an HRV measurement at the same time, under the same conditions (e.g., first thing in the morning, relaxing in bed), every day for as long as two months to establish an accurate baseline range off of which you can base your training and lifestyle decisions. PrimalBeat HRV allows you to archive each day’s morning reading with the touch of a button, and view your HRV readings (including the important HF and LF frequency scores—details in this podcast with HRV expert Ronda Collier) over time in a convenient graphic layout. For example, if you proceed with measurements over two months of normal lifestyle circumstances and training patterns and see most every HRV score falling between 65 and 75, this becomes your baseline range. If, on the heels of stressful events like jet travel, challenging workouts, or insufficient sleep, you obtain an HRV score in the 50s, this is a strong sign to back off on training and other stressors until your HRV scores return to normal range.
I will cover the topic of HRV in great detail in the upcoming Primal Endurance book, slated for release in early January, 2016. Brad Kearns, my Primal Blueprint Publishing sidekick and writing partner on Primal Endurance, relates an interesting story in the book where he experienced a delayed HRV suppression 36 hours after a stressful workout, but no change in resting heart rate over the same time period. With his more detailed biofeedback, he stayed in rest mode despite feeling fine and have a “green light” resting heart rate. Over time, these are the kind of training decisions that enable uninterrupted improvement and prevent burnout. To put it more simply, HRV can often be smarter than you when it comes to regulating the stress patterns of your workouts and life.
If you are an iPhone user, check out this app and start getting into it. Android users can look for other HRV software such as iThlete. If you’ve been tracking HRV for a while, please comment on your experiences. I’d love to hear your thoughts.
Note: If you’re familiar with Sweetwater Health’s existing Sweetbeat Life HRV app, PrimalBeat HRV uses the identical top of the line mobile HRV technology. The Sweetwater folks agreed to customize their product and brand it Primal in pursuit of our mutual interest of promoting HRV to as many folks as possible. Furthermore, Sweetwater Health is providing the customer support for PrimalBeat HRV app, so either of the branded products you choose is great.
Prefer listening to reading? Get an audio recording of this blog post, and subscribe to the Primal Blueprint Podcast on iTunes for instant access to all past, present and future episodes here.