How to use heart rate variability as a training tool

How to use heart rate variability as a training tool

As running technology gets smaller and more portable, the number of insights it offers into our health continues to grow. For wearable heart rate monitors, the tech has gone beyond simply providing data to reshaping the way many runners train and race. Instant access to the beats-per-minute (BPM) metric has made training by heart-rate zones the go-to training guide for many. Yet, there’s much more our hearts can tell us than how hard it’s working. Heart rate variability (HRV), an increasingly popular metric for runners, offers subtle insights that our hearts reveal between the lines—or between the beats—that can help us better understand our overall running health and guide us in tweaking our training accordingly.


What is HRV?

Unlike heart rate, HRV focuses on the gaps between the beats. Specifically, it’s a measurement of the natural changes in tempo from one beat to the next. It’s a concept that’s probably familiar to anyone who’s ever tried playing the drums (or has lived on the same block as someone who has). An experienced drummer with rock-solid timing can hold the tempo perfectly between successive beats, so their “variability” is low. A shaky beginner who keeps striking the snare a little too early or too late, meanwhile, has high variability. There are big differences between heartbeats and drumbeats, of course, and one in particular may make HRV seem a bit counterintuitive. While metronomic timing is great for drummers (and listeners), it’s not necessarily ideal for runners. In general, a heart that doesn’t keep the tempo exactly right between beats, like our fledgling drummer friend, reflects better overall health.


What can HRV tell us?

HRV can reflect several aspects of a runner’s overall health and fitness, for example, how well a body is adapting to training load or stress. If your HRV remains relatively high, it suggests the body is effectively recovering and adapting to the demands of your workouts. Conversely, a consistently low HRV may indicate inadequate recovery or excessive training stress, which could increase the risk of overtraining or injury.

HRV can also serve as a tool to gauge recovery. Lower HRV values ​​are generally associated with fatigue and insufficient recovery, whereas higher HRV values ​​indicate a readiness to perform. A higher HRV is generally associated with better cardiovascular health, overall fitness and improved autonomic nervous system function. A high HRV can also reflect the state of your mental and emotional well-being, like lower stress levels and improved mental resilience.

Garmin Forerunner 965
Photo: Garmin

How is it measured?

HRV measurement is increasingly becoming a standard feature of portable running tech. It has been incorporated by companies such as Polar and Wahoo into chest strap heart-rate monitors, as well as smartwatches and fitness trackers by brands including Apple, Coros, Garmin and Fitbit. While the steps for taking measurements will vary by device, readings are taken when at rest while seated or lying down. Scores are most commonly expressed in milliseconds, with higher scores tending to reflect better overall health.

What do I do with the results?

Although HRV can provide a helpful snapshot of trends in your overall health, what the numbers mean from one runner to the next can be, rather fittingly, highly variable. As with maximum heart rate, a strong HRV score will continue to drop as runners get older, and even between healthy runners of the same age, scores can vary wildly. That’s why, when making sense of your HRV, it’s more valuable to look at which direction your numbers are trending, rather than trying to hit a score that may not reflect your overall health. Numbers that trend higher indicate improvements in fitness and overall health and may reflect your readiness to increase the intensity of your training. A string of decreasing scores could suggest one or more aspects of your overall health could use more attention.

healthy food

What HRV numbers won’t tell you is what you need to fix. Because HRV can be shaped by many factors—level of physical activity, psychological and emotional stress, diet and sleep quality among them. In addition to taking HRV measurements daily, it’s important to regularly—perhaps once a week—check in with yourself on each of the above factors in your overall health, identify where you might be falling short and what changes need to be made (such as getting to bed earlier or eating more nutritious meals). Note how the changes affect the direction of your HRV scores in the coming week and see if that helps.

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