Heart Rate Variability – How Can It Help Your Training?

Have you seen a health statistic on your watch called HRV and wondered what it means?

You can think of your daily HRV measure as an indication of training readiness.

HRV is a measure of the gap between your heart beats. If your heart rate is 60bpm, the gaps between each beat might be 1.1s, .9s, .8s, 1.2s for example. There is a subtle variation in the rhythm of your heart beat, and HRV measures that variation.

Why is HRV important? Because it is a measure of the way your autonomic nervous system (ANS) is functioning, which gives you a very good insight into how your body is coping with the everyday stresses in your life, so you can use it to help guide your training and keep yourself healthy.

Your autonomic nervous system regulates a variety of bodily functions as well as your heart beat. It regulates your blood pressure, your breathing, your digestion – pretty much every bodily function that doesn’t require conscious thought.

The Autonomic Nervous System has two main parts:

  • The Sympathetic Nervous System – the “fight or flight” mode
  • The Parasympathetic Nervous System – the “rest and digest” mode.

The sympathetic nervous system responds to stressors by increasing your heart rate and blood pressure while the parasympathetic slows down your heart rate and lowers your blood pressure when you are feeling calm and relaxed.

If you’re in fight-or-flight mode and your heart is racing, there won’t be much time between heart beats and your HRV will tend to be lower. When you are relaxed your heart will beat slower, meaning there is more time between beats for variations – so your HRV will be higher.

The part of the ANS which is most-activated at any point in time depends on whether you are stressed or relaxed – so therefore your HRV is a good indication of how your body is coping with your current lifestyle.

How is HRV measured?


Most wearable devices, including Garmin and Coros Watches, Whoop Bands and Oura Rings, measure your HRV using the optical heart rate reader and they take an average over a long period of sleep each night.



What is a “normal” HRV?

There isn’t really a "normal" HRV figure to strive for. It varies a lot from person to person and can be anything from 20ms to 200ms (it is measured in milliseconds). What matters most is how your current reading compares to your own longer-term average. Your watch will tell you this.

For example – your average range over the past few months might be 48-62ms.

If you have slept badly, are feeling highly stressed, have eaten sugary food, had alcohol to drink or have picked up a cold or virus – then you might wake up to an HRV of 35ms – which would be low for you.

If you have sleep well, been eating healthily and you are feeling relaxed then you might wake up to an HRV of 75ms – which is high for you.

A low HRV is an indication that your body is not coping well with the current stressors in your life so it is an indication that your training might need to be modified. A hard interval running session or a long run will cause further stress on your body which could lower your HRV further and drive you towards ill health.

A high HRV is an indication that your body is well rested and recovered and so it is an indication that you could cope with a harder training day.

By using HRV in this way you can make an informed decision on what type of training to do on any given day and help to keep yourself fit and healthy in the process.


Can you improve your HRV?

Yes you can, and unsurprisingly it is the normal everyday healthy lifestyle choices that are thought to have the biggest influence.

  • Exercise
  • A good healthy predominantly whole food diet
  • Improving your sleep (trying to get 7-8 hrs/night)
  • Reducing your stress (this can be the hardest to control)
  • Spending time outdoors
  • Spending time with family and friends
  • Drinking less alcohol

If you are a runner, and you are following a training plan, you are probably subjecting your body to a fairly high level of exercise-related stress. Some of this stress is good for you, it is ultimately how you become a better runner. But too much stress for a sustained period of time is bad for you (overtraining).

If your watch measures HRV then I would highly recommend taking an active interest in your nightly readings. Try to get a feel for the correlation between your HRV number and how you feel health and fatigue-wise. They should be fairly closely aligned.

One of the huge potential benefits of HRV is its predictive nature. Your HRV might drop one night, but you still feel relatively healthy - however, the next day you wake up with a head cold. In this case your heart has reacted to the viral stress before you were aware of it. If you learn how to use your HRV value to best effect, you can modify your training accordingly and improve your chances of staying healthy. 

Using HRV to modify and motivate your daily lifestyle choices

Knowing your HRV score is also a way to measure the effect of your current lifestyle choices (diet, exercise, sleep, alcohol) and that can be quite motivating. If your HRV is gradually getting lower over time, then you can focus on getting more sleep and eating better quality food, and as a result your training (and your race result) should improve.