Often overlooked, heart rate variability (HRV) is an important indicator of health and fitness. The metric has been around for a while but its only now that its gaining more attention. This is because HRV is becoming more accessible to the average person and not just medical professionals and the fitness pros.
What is it?
When you measure your heart rate, you will get a beats per minute value. At rest, this ranges between 60 and 80 for most people. The fitter you are, generally the lower your resting heart rate. This is due to the heart getting bigger and stronger with exercise, and getting more efficient at pumping blood around the body.
Essential reading: Lowering your resting heart rate with wearables
However, your heart does not beat with a steady rhythm. The intervals vary from one heartbeat to the next. And this is where HRV comes in. Put simply, it measures the variation in the time interval between heartbeats.
It is all linked to your sympathetic and parasympathetic nervous system. These are parts of your autonomic nervous system that control your body’s survival functions such as breathing, heart rate, digestion, organ control and blood pressure.
The sympathetic part of the nervous system is linked to the fight or flight instinct. It fuels your body into action when needed. The parasympathetic part is the counterpart. It helps your body to rest and recover when shocked by the sympathetic nervous system. All of this is controlled by a region of your brain called the hypothalamus. It send signals to your body to either stimulate it or relax it.
HRV is a way to determine the resilience of your autonomic nervous system, i.e. how quickly it can shift from one to the other state. Many factors can influence this such as whether you’ve had enough sleep, the quality of your diet, your social life, stress and more.
Making sense of the data
According to the American Heart Association, the average HRV is 59.3. This varies, though, depending on age and gender.
Unlike your resting heart rate, you should be aiming for a high HRV. It’s a bit counter-intuitive but a healthy HRV should not be beating at a perfect tempo. Yes, you read correctly. Research has shown that when your HRV is high, your body is showing better stress resilience and health. Typically, a higher HRV is also correlated with a younger biological age and better cardiovascular fitness.
A low HRV (little variation between beats), on the other hand, indicates less resilience. You’ll get low values when you are overloaded with stress, are sick, have not slept well or have been working out a bit too much. This is when its good to take some time to recover. Recovery makes performance possible. A lot of the progress happens in recovery.
A few low values should not be of concern as your HRV will vary from day to day. We all have our good days and bad days. But if your HRV is consistently low it could be an indicator of health problems. Best to consult a doctor if this is the case.
Measuring with wearables
HRV is measured by looking at the spaces between R waves on an EKG. This is just a fancy way of saying you’re looking at the difference between heartbeats. The good news is that you no longer need a doctor or EKG to measure your HRV.
Many sports watches and some fitness trackers measure this. For example, most of the latest crop of Garmin fitness trackers keep tabs on your stress 24/7 by monitoring your HRV. Some sports watches go even further and calculate the stress of training on your body. Then they let you know when its safe to exercise again. The high-end Garmin sports watches and cycling computers tap into Firstbeat metrics to achieve this, as do many other watches. The full list of compatible devices can be found on this link.
Essential reading: Best heart rate training monitors
There are also apps you can download. Some of them are free, such as the Elite HRV and HRV+. Unfortunately you cannot use fitness trackers and sports watches with them as they do not broadcast raw HRV values.
For this you’ll need devices that capture and share these metrics. What follows are some great options which broadcast HRV in raw form. We’ve added a couple of other devices that don’t broadcast values but do provide you with the raw data in their own smartphone app.
If you want a reliable heart-rate monitor and can live with strapping onto your chest, the H10 is now one of the best options out there.
It takes all the features of the best selling H7 and slaps on better accuracy, an improved non-slip design, the ability to use on two devices concurrently and on-board memory. And lets not forget the water resistance with live data for compatible devices. Link all this to the Polar Beat iOS/Android app, and you suddenly have a coach guiding you during your workouts in real-time making sure you are in the correct heart rate zone to achieve your goals.
RHYTHM24 is a heart rate monitor for your forearm or upper-arm. Its made of a silicone and polycarbonate hybrid with a soft elastic strap. This makes it comfortable to wear and much easier to put on than a chest strap.
The device boasts Valencell’s latest PerformTek technology, which reads your heart rate through your skin with both green and yellow optical sensors. This combination ensures greater accuracy across all skin tones.
Boasting the same Bluetooth Smart and ANT+ connectivity of its predecessor, RHYTHM24 brings a number of improvements. As its name implies, the gadget will now run a full day between charges, a significant boost to the 8 hours of its predecessor. Its also waterproof, has internal memory and comes with a number of sports modes.
Wahoo TICKR X
Tickr X is the most advanced of Wahoo’s three heart rate training chest straps. In addition to information on your ticker, the device measures calorie burn, running form metrics, indoor run, spin cadence and counts reps during strength training.
Its internal memory can store up to 16 hours of heart rate data allowing you to leave your smartphone behind and sync later. Both ANT+ and Bluetooth 4.0 capabilities allow the Tickr X to connect to GPS watches, iPhones and Android devices as well as numerous third-party apps.
Suunto Smart Belt
Size really matters. At least it does if you ask Suunto. The company says their product is the smallest Bluetooth Smart compatible heart rate sensor on the market. The sensor module is tiny and weights only 40 grams, while the strap width is only 30 millimetres.
When running, the tracker provides real-time heart rate data and calories burned. You can use it while swimming as well, as its water resistant up to 30 metres.When you are back on dry land, sync the device to your smartphone app on your Android or iOS phone for post workout analysis.
This GPS fitness watch is marketed as a versatile training tool for a variety of sports and activities. What’s most unique about it is that Polar has slapped on advanced sleep analysis, overnight recovery insights and personalised and adaptive training guidance. These take sleep parameters, heart rate measurements and recovery into account to offer deep insights into the state of your body.
As part of this you get something Polar calls Nightly Recharge. This looks into how quickly your autonomic nervous system calmed down during the early hours of your sleep and how well you slept. The info is tied in with your daily activity stats to let you know whether to take a days rest or train as usual.
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