Heart rate training is one of the more scientific approaches to cycling training, as your heart rate during exercise is strongly correlated with your effort level and intensity based on the percentage of your VO2 max.
However, in addition to the utility of monitoring your heart rate during exercise, or even resting heart rate, it can also be helpful to look at your Heart Rate Variability (HRV).
Heart rate variability is a relatively new concept in the fitness and medical communities.
However, as research continues to uncover the many benefits of heart rate variability, it’s quickly becoming a biometric that cyclists should consider monitoring in their own training.
In this article, we’ll be covering:
- What Is Heart Rate Variability?
- Why Does Heart Rate Variability Matter?
- Benefits of Heart Rate Variability Tracking
- How To Track Heart Rate Variability
- What Is A Good Heart Rate Variability (HRV) For Cyclists
- Heart Rate Variability Chart
- How To Use HRV In Your Training
- How To Improve Heart Rate Variability
Ready for the lowdown on what is a good heart rate variability?
Let’s jump in!
What Is Heart Rate Variability?
Heart rate variability is essentially a measure of the variability in the length of time between each heartbeat.
When you have low heart rate variability, your heartbeat is even and steady.
A high heart rate variability indicates that the time between each heartbeat is variable, so there is a less consistent, steady rhythm to the heart.
In other words, the higher your heart rate variability, the more fluctuation there is between the spacing of any two consecutive heartbeats.
If your resting heart rate is 60 bpm, your heart isn’t beating exactly one contraction per second for the entire minute. There are small differences in the number of milliseconds between the spacing of each of the 60 heart contractions during that minute.
From beat one to beat two, it might be 0.9 seconds. From beat two to beat three, it might be 0.95 seconds. From three to beat four it might be 1.1 seconds, and so on.
Again, the higher your heart rate variability, the greater these differences will be.
Whereas, with a low heart rate variability, the intervals between each heartbeat will be much more consistent.
Why Does Heart Rate Variability Matter?
It’s might be counterintuitive to cyclists, but it’s actually better to have a higher heart rate variability (greater fluctuations in your heart’s rhythm).
Research demonstrates that a high heart rate variability is indicative that your heart is “ready” for high-level performance and other stressors.
But why does heart rate variability exist in the first place?
The heart rate is controlled by your autonomic nervous system. This is the branch of the nervous system that automatically regulates things under your unconscious control, such as your heart rate, breathing, blood pressure, and digestion.
The autonomic nervous system is subdivided into two major sections, which essentially work in opposition to control these various essential physiological processes, including heart rate.
The sympathetic nervous system, linked to the “fight or flight” response, activates the body and prepares it for stressful situations.
This can be anything from killing your hard workout with high-performance exercise to dealing with a last-minute work request for a big project.
The antagonist division of the autonomic nervous system is called the parasympathetic nervous system – nicknamed the “rest and digest” system.
While the sympathetic nervous system primes the body for action, the parasympathetic nervous system slows things down for resting conditions.
The balancing act between these two divisions is what determines not only your heart rate but also your heart rate variability.
The autonomic nervous system is closely linked with heart rate variability.
Fluctuations between heartbeats increase when the body and brain are in a relaxed state, indicating the parasympathetic nervous system is dominant.
When the sympathetic nervous system is predominantly controlling your body, heart rate variability is lower.
In this way, measuring your heart rate variability can provide a window into which nervous system is commanding the body, and the degree of stress your body is under.
Heart rate variability can serve as a measurable, observable biomarker for something that’s otherwise not easy to quantify or measure: physiological stress.
Moreover, we know that physiological stress affects our exercise performance.
High levels of acute stress can increase the risk of injury and illness and may reduce peak performance.
More concerning is prolonged stress, which can lead to non-functional overreaching and then overtraining syndrome.
When you have good heart rate variability, your nervous system is well balanced and your body is coping well with stress.
The sympathetic division is appropriately stimulating the heart and telling it to beat faster and the parasympathetic nervous system is slowing your heart rate in an even-steven manner.
Higher heart rate variability is therefore a good indication that you are recovering well from your workouts and that your body is prepared for the next high-intensity effort.
What Are The Benefits of Heart Rate Variability Tracking?
Here are some of the top benefits of tracking heart rate variability for cyclists:
- Providing a non-invasive way to assess physiological stress and nervous system performance.
- Providing an insight into your recovery from workouts.
- Helping prevent overtraining syndrome.
- Serving as a sign of fatigue and/or dehydration, and a potential warning sign of illness.
- Helping to give insight into your body’s “readiness to train”.
How to Track Heart Rate Variability
Although the most accurate way to measure your heart rate variability is through an electrocardiogram (ECG), high-end wearable fitness trackers and heart rate monitors can also measure heart rate variability.
It’s not a measurement that holds much utility during exercise (it’s more applicable at rest). Also, because it’s fairly sensitive, a large volume of data should be used to determine your average heart rate variability.
High-end fitness tracking devices will actually take a weighted average of your heart rate variability, placing more importance on your heart rate variability during sleep (particularly in certain stages of deep sleep, as greater heart rate variability will be seen in relaxed states).
Other cycling watches, such as the Garmin Fenix line, can do a full 3-minute HRV tracing if you use a chest strap heart rate monitor.
Ultimately, being consistent with how and when you measure your heart rate variability will be the most effective way to track changes in your physiological stress levels and state of recovery.
What Is a Good Heart Rate Variability (HRV) for Cyclists?
Although we love to be able to compare ourselves to others, the truth is that there isn’t really a “good“ heart rate variability for cyclists that can be generalized to everyone.
Rather, heart rate variability is a highly individual metric, and its usefulness really comes into play on a personal level in terms of your own trends and changes in heart rate variability.
With that said, across the population, heart rate variability tends to decline with age, be slightly lower in females, and increase with improved training status, so elite cyclists will tend to have a higher heart rate variability than novices.
Heart Rate Variability Chart
The approximate mean HRV by age and sex according to fitness data-crunching firm WHOOP can be seen in the HRV chart below:
|Age||Average HRV for Women (ms)||Average HRV for Men (ms)|
How to Use HRV In Your Training
If you start tracking your HRV, you will probably notice that your heart rate variability drops after several days of hard workouts, inadequate sleep, poor diet, or a combination thereof.
But, does it matter? How can you use HRV to improve your training?
Some research has suggested that using HRV to guide training can indeed be an effective approach at improving cycling performance.
For example, one study used the 7-day rolling average of HRV as taken in the morning using a Polar H7 chest strap heart rate monitor to inform the workout for the day over the course of an 8-week training intervention.
When heart rate variability was low, for instance, cyclists would take an easy or recovery ride, whereas high heart rate variability days were taken to be signs that the body was ready for a high-intensity workout.
Using this approach of letting HRV guide the workout plan resulted in significantly greater increases in peak power (5%), power at VT2 (14%), and power over the 40-minute time trial (7%) compared to traditional training, where neither peak power nor 40-minute time trial power improved.
Ultimately, when your heart rate variability is high, it’s a green light to push your body with a more strenuous workout. When your heart rate variability is low, it’s time for a rest day or recovery workout.
How To Improve Heart Rate Variability (HRV)
Fortunately, most of the measures shown to affect your heart rate variability are the same habits we should try to embrace to live a healthy lifestyle in general.
Some steps that are known to be especially closely linked to how to increase HRV include:
- Regular Exercise: Over time, consistent exercise will help increase your HRV. However, in the short term, strenuous activity actually decreases your HRV – so it’s important to be wary of overtraining, especially just before a race.
- Healthy Sleeping Habits: Getting enough sleep is essential for many aspects of our health, and improving your heart rate variability is no exception. Regular sleep patterns will help your circadian rhythm, which is linked to HRV.
- Reduce Your Alcohol Intake: Another one that will come as no surprise, excessive alcohol consumption is linked to decreased HRV. The short-term effects diminish within about 5 days, but chronic alcohol use is likely to have wider consequences.
- Reduce Stress: Another of the wide-reaching health effects of excessive stress is its negative influence on HRV. Getting regular sleep, exercising, and practicing meditation can all help reduce stress and increase HRV.
- Diet and Hydration: Following a healthy cyclist’s diet and keeping well hydrated are vital for maintaining a healthy lifestyle and will both have a positive effect on HRV.
Besides these general health points, there are a couple of steps you can take that are more uniquely linked to how to increase HRV:
- Cold Exposure: Brief exposure to the cold, such as plunge pools and ice baths, engages your vagus nerve. This in turn stimulates the parasympathetic nervous system, dictating HRV.
- Light Exposure: Getting out and about in natural daylight is essential. Besides helping with sleep patterns, it also reduces stress, increases vitamin D production, and promotes healthy hormone responses – all of which help increase your HRV.