Unlike your resting heart rate, which you can measure easily with just a stopwatch and your finger, tracking heart rate variability (HRV) is a bit trickier. In the past, it required an EKG at the doctor’s office. Now, smartwatches and other wearables make it easy to track HRV, and many top athletes and coaches use it to adjust their workouts.

HRV is another piece of data that could be useful, but it can also be confusing because many factors affect it. Unlike heart rate or sleep cycles, it's not as easy to understand, and the reason for a change in HRV isn't always clear.

Heart rate variability (HRV) can be hard to understand, and most doctors—even heart specialists—don’t use it when deciding on treatments. So, is it something worth keeping an eye on, or just an extra feature on your smartwatch that you can ignore?

Everything you need to know about heart rate variability, why it can be tricky, and how looking closely at your own numbers might help you perform better on the bike.

What is heart rate variability and what should it be?

You probably know that heart rate is the number of times your heart beats per minute. Your resting heart rate is the number of beats when you’re completely at rest, usually measured right after you wake up in the morning before getting out of bed. Heart rate variability (HRV) goes deeper, looking at the tiny differences in time between each heartbeat.

The Physiology Behind HRV

HRV reflects the balance between the sympathetic nervous system (SNS) — your fight-or-flight response — and the parasympathetic nervous system (PNS) — your rest-and-digest mode.

Sympathetic dominance (after intense training, stress, caffeine, lack of sleep) tends to lower HRV.

Parasympathetic dominance (good recovery, relaxed state) tends to raise HRV.

Generally, a higher HRV is better and shows that your body is healthy, fit, or ready for training. A lower HRV usually means your body is under stress, either physically or mentally. This stress can come from many things, like having a cold, drinking alcohol, not sleeping enough, or feeling anxious about work. Daily stress has been shown to lower HRV. Since HRV goes up when your body is in “rest and digest” mode, it is sensitive to stress, which usually brings the number down.

What Should HRV Be?

Heart rate variability (HRV) naturally changes over time—that’s what “variability” means. These normal ups and downs usually aren’t a sign of heart problems. However, some heart rhythm issues can cause sudden changes in HRV.

The question of what your HRV should be is much more complicated. First of all, there’s a wide range that’s considered okay: An adult’s score can fall anywhere from under 20 to over 200 and still be considered normal.

How do you track your heart rate variability?

In the past, tracking HRV meant being hooked up to EKG electrodes in a doctor’s office. Some chest straps still use these electrodes and can measure heart rate very accurately, but they aren’t comfortable to wear while sleeping. That’s why other devices, like smartwatches and rings, are better for tracking HRV. Instead of electrodes, these wearables use a light-based technology to gather HRV data.

1. Wearables and Sensors

Most cyclists use one of the following:

Chest Strap/Armband Heart Rate Monitors

Devices like Polar H10 are considered gold-standard for HRV because they measure R-R intervals (beat-to-beat timing) directly. Another excellent option is Coospo Heart Rate Monitor, which offers accurate HRV, reliable Bluetooth and ANT+ connectivity, and pairs seamlessly with Coospo bike computers and apps. Many cyclists appreciate its comfort during long rides and the ability to capture HRV data while training or sleeping.

Wrist-Worn Devices

Garmin, WHOOP, Oura Ring, Apple Watch, and Fitbit can provide HRV data, though accuracy varies by device and measurement context.

2. Where and When to Measure

Timing is key:

• Morning measurements — typically performed right after waking up — are most consistent.
• Measurements should be taken in a resting state, ideally supine (lying down), breathing naturally.

Regular measurement at inconsistent times or during stress, caffeine intake, or after training can distort trends.

How HRV is calculated can vary between devices. Some measure it at night, others first thing in the morning, which can cause slightly different results. This is why it’s hard to compare your HRV with someone else’s.

It’s best to track your HRV for at least four to eight weeks before trying to interpret it. Don’t just look at the number on your wrist each morning. While you’re finding your baseline HRV, keep a diary too. Record things like caffeine, sleep, and hydration—anything that could affect your HRV. After tracking for that time and noting these factors, you can start to understand and use your HRV more effectively.

Why does heart rate variability matter for cyclists—and how can it inform your training?

HRV can be very helpful in training because a higher HRV usually indicates good training readiness. For example, if you notice your HRV is on the high end of your average, you might increase the intensity or duration of your upcoming workout.

If your number is lower than usual for more than just one day, it could mean you’re pushing yourself too hard and need to slow down. Watching these numbers can help you avoid injury or overtraining because a consistently low HRV can be an early warning sign. It may signal to you or your coach that it’s time to adjust your training.

Other things, like being dehydrated or tired, can also lower your number, so it’s not always overtraining. Still, it’s a good idea to check your schedule and see if you need to slow down.

Elite athletes and coaches are now using HRV to guide their training. In fact, a 2018 study in the International Journal of Sports Physiology and Performance found that planning daily workouts based on HRV can help improve peak power more than following a traditional periodized training plan.

Top athletes are always looking for small advantages, so some high-level coaches use this data. For most people, using HRV this way depends on how much you want to see how daily choices affect your HRV—and whether you can adjust your workouts to different days depending on if your number is above or below your usual level.

Again, it is only a guideline and has a fair amount of variation from day to day, so it is probably better used for looking at trends rather than everyday changes to a training program.