Heart Rate Variability is a powerful data tool for guiding a cyclist’s training and recovery, but it isn’t the only wrench in the toolbox.
Cyclists like to push the limits. They are constantly seeking the perfect ride by stretching the boundaries of their ability, learning more about themselves and what their bodies can do.
Most of us don’t have the talent or desire to pursue our passion as a professional. Life’s challenges and personal stressors burden us—the physical and mental toll of training and racing multiply the consequences of inadequate recovery.
Finding a balance between recovery, adaptation to training stimulus, and stress is essential to optimal performance and health: the more information available to help us make sound decisions, the better. Heart Rate Variability is just that.
Introduction-Heart Rate Variability and Cycling
Heart rate variability (HRV) is a way to monitor an individual’s sleep, recovery, performance, and overall wellness. High HRV is a strong indicator of heart health, and several studies link elevated HRV to reduced mortality, improved psychological well-being, and a better quality of life.
It is directly related to how our nervous system responds to stress and physical strain and serves as a reliable recovery gauge. HRV data provides valuable and easily interpreted feedback that helps an athlete perform better, make informed training decisions, and improve well-being and health.
Heart Rate Variability isn’t the only piece of the cyclist’s training decision kit, however.
What is Heart Rate Variability?
Heart rate variability (HRV) is a measure of the time difference between our heartbeats. Our hearts don’t beat in an even uniform manner. There is variability in the time between heartbeats, measured in milliseconds, continually changing depending on many factors.
The autonomic nervous system regulates HRV and can tell us a lot about it. The autonomic nervous system consists of two parts.
The sympathetic branch is the fight or flight system that prepares us to react in times of stress. During exercise, the sympathetic system increases the rate and force of our heartbeat—a decrease in HRV results.
The parasympathetic branch returns us to a calm state following a stress reaction and slows our heart rate – an increase in HRV occurs.
What Causes a Positive Effect on HRV and Cycling?
When we sleep restfully, meditate, or engage in enjoyable activities, the parasympathetic system takes over. Relaxation and low-stress activities have a beneficial impact on HRV, causing it to increase.
HRV is generally higher when the heart is beating slower. The lifestyle choices we make have a significant impact on HRV as we work to improve the balance in our lives. It’s a good thing.
What Has a Negative Effect on HRV and Cycling?
When confronted by a stressful situation, elevated sympathetic activity prepares us to react. Our heart rate increases, and HRV decreases. The same is true of exercise. The sympathetic nervous system gets us ready to go at the beginning of a training session. Our heart rate increases blood flow to our muscles and readies us for the fight to come. It is a normal response.
The trouble starts when we are repeatedly faced with stress, mentally or physically. The chronic overload upsets the cooperation between the two systems. Our body enters a persistent sympathetic state, always ready for a fight.
We don’t sleep well, tend to make poor food choices, and things begin to spiral out of control. The strain on our bodies causes various mental and physical health-related issues.
Our HRV remains low, even during times of rest. The same is true of exercise when we are overreaching and poorly recovered. Our parasympathetic system wants to lull us into recovery mode, but the sympathetic wins out. It’s a bad thing.
How Do You Measure and Monitor Your HRV?
Most widely available wearable devices, like the Apple watch or Whoop, use photoplethysmography (PPG) to detect our heartbeat optically. The inter-beat interval (IBI) calculates your HRV by measuring the wave of blood flow.
Not all heart rate monitors have this capability. In addition to the accurate measurement of IBI the monitor must also have the capacity to transmit the unaltered interval data via Bluetooth or Ant+.
There are many apps and computer programs that take it from there. The merits of each are beyond the scope of this article. Suffice to say; there are plenty of numbers to go around.
The Science Behind Cycling Training With HRV
In a recent study published in the Journal of International Sports Physiology and Performance, researchers compared traditional cycling training to an HRV-guided (HRV-G) training program. Seventeen cyclists were divided into two groups and monitored for eight weeks.
The HRV-G group followed a program based on the HRV data of the athletes. The traditional group followed a more typical program of three weeks of progressively increased intensity followed by a week of recovery.
Following the eight weeks, the HRV-G group of cyclists spent more time training at high and low intensity than the traditional group, which had more time training at moderate intensity.
The authors attributed the improvements shown by the HRV-G athletes in Maximal Aerobic (1 min.) Power, Power at FTP, and 40-minute Time Trial Power to optimizing training time at high intensity when the athletes were well prepared. While also limiting the time at moderate intensity, the researchers replaced that with low and recovery-paced training.
How to Use HRV to Guide Your Cycling Training
To utilize your HRV data effectively, you must record a meaningful amount of baseline readings. Once you have established a baseline, the next step is to identify trends and correlate them to your training load and how you are feeling.
If your HRV is low, your training volume and intensity have been higher than usual, and you feel achy and tired, it may be time for some recovery. If you awaken the next day after a restful sleep and your HRV is near the baseline, then you are good to go.
If your HRV still hasn’t returned to or below your baseline, but you feel recovered and mentally ready to resume training, it is time to let experience take over. HRV is a practical guide, but it is not absolute since it can be affected by a significant number of outside variables.
When uncertainty creeps in, and you want to push out one more high-intensity session during your training block, your body doesn’t feel right. That is when HRV can make a difference and guide you toward sensible training decisions.
On the other hand, your training intensity and volume have been up, you’re nearing the end of a long progressive build period, and you feel motivated. Check your HRV. If you are recovering well mentally and physically and your HRV confirms it, add another session or two of intensity.
Monitor your data, identify the trends, and observe the mental and physical signs. Over time you will develop an instinct based on experience. Make an individual decision based upon personal experience and long-term evidence.
Can HRV Tell You When You Are Overtraining?
A recent study published in the British Journal of Sports Medicine followed eight Grand Tour pros during the Vuelta a Espana to answer this question. The researchers chose the Vuelta because it comes towards the end of the professional racing season, after the Giro d’Italia and Tour de France. In addition to the high level of exercise and intensity and volume associated with this grueling race.
If there were a time during the season when a professional cyclist would suffer from overtraining, this would be it. The authors closely monitored the racers for several metrics, one of which being HRV.
The researchers found a strong inverse correlation between resting HRV and exercise volume and intensity. The HRV values increased from baseline to Stage 10 of the race. Then remained high through to the end. According to the researchers, however, this wasn’t the whole story.
It is Important to Consider the Athlete as an Individual
To reliably diagnose overtraining and overreaching, an assessment of HRV data must account for individual differences in an athlete’s response and adaptation to a training stimulus.
Athletes who showed the most significant cumulative physical exertion also showed the largest decline in HRV. The relation to chronic physical exertion will be achieved by developing a way to normalize an athlete’s individual psychosocial, neuroendocrine, musculoskeletal, and cardiovascular responses.
In short, the researchers acknowledge a direct relationship between chronic exercise and an increase in HRV across the group of racers. The effect that it has on each racer independently and the risk of overtraining are less clear.
It doesn’t mean that you shouldn’t monitor YOUR individual response to training overload and make the appropriate adjustment. If you have been training and racing hard for a while, your body feels it, and a low HRV is telling you, too. The warning signs are unmistakable.
Conclusion-Heart Rate Variability and Cycling
Cyclists love data and numbers, virtual cyclists in particular. Heart rate variability is a solid indicator of recovery, but it is not the only one. Many cyclists lose track of the importance of listening to what their body tells them—prefer to let their training devices do the mental math.
Others prefer to abandon all technical assistance and ride by feel. A happy medium is in order here.
HRV variability is one of the few data points that provide a view of what’s going on inside your body. HRV is a direct measure of how your nervous system is reacting at a given moment. Put HRV data near the top of the priority list in terms of recovery decision-making importance.
Knowledge is Watts! Use HRV to guide your decisions and become a healthier and more fit cyclist.
What device and app do you use?
Do you monitor and assess your HRV data to make training and recovery decisions? What do you find that works best for you? Comment below! Your fellow virtual cyclists want to know.
If you found this article informative and want to find more like it, check out the Training & Performance page on The ZOM!
Semi-retired as owner and director of his private Orthopedic Physical Therapy practice after over 20 years, Chris is blessed with the freedom to pursue his passion for virtual cycling and writing. On a continual quest to give back to his bike for all the rewarding experiences and relationships it has provided him, he created a non-profit. Chris is committed to helping others with his bike through its work and the pages of his site.
In the summer of 2022, he rode 3,900 miles from San Francisco to New York to support the charity he founded, TheDIRTDadFund. His “Gain Cave” resides on the North Fork of Long Island, where he lives with his beautiful wife and is proud of his two independent children.
You will read him promoting his passion on the pages of Cycling Weekly, Cycling News, road.cc, Zwift Insider, and Bicycling. Chris is co-host of The Virtual Velo Podcast, too!