Daily HRV monitoring does not affect average cycling performance, but it is significant in a few key areas critical to eracers.
Wearable technology is the number one fitness trend for 2022, according to a recent survey conducted by the American College of Sports Medicine. Activity trackers, smartwatches, heart rate monitors, and GPS tracking devices make up a $100 billion industry in the US alone. The wealth of information they provide, like blood pressure, oxygen saturation, respiratory rate, and even EKG, make them a must-have for many athletes.
Several key performance and recovery metrics make the use of wearable technology appealing to cyclists. When balancing recovery, training adaptation, and stress, many cyclists turn to their tracking devices for much-needed data. Heart rate variability (HRV) is one such data point.
Athletes and Coaches Use HRV for Performance
Athletes and their coaches use heart rate variability to monitor sleep, recovery, performance, and overall wellness. HRV data provides valuable and easily digestible feedback. Proponents believe it to be a reliable predictor for mental stress, physical strain, and overall recovery.
Our hearts don’t beat in an even uniform manner, and HRV measures the variation. The variability, measured in milliseconds, continually changes depending on many factors. The information gives valuable insight into the state of our autonomic nervous system and its two branches.
HRV Gives Insight Into the State of the Nervous System
The sympathetic ‘fight or flight’ branch prepares us for times of stress. A decrease in HRV during exercise shows an increase in the rate and force of our heartbeat. An increase in HRV occurs when the parasympathetic branch eases our heart rate to a calm state following stress.
Several recent studies have pointed to the successful utilization of HRV to guide training. The research shows that HRV data is most valuable to athletes when they establish a baseline and identify trends.
Athletes correlate subjective reports of how they feel with training load and HRV-derived recovery data to make informed performance decisions and improve their well-being. HRV data is a helpful guide for athletes and their coaches when used to assess performance during an extended window, but many not be helpful day-to-day.
The Study of 25 Trained Cyclists
A December 2021 study published in the Journal of Science & Cycling by scientists from Kansas State University’s Kinesiology lab confirms this belief. The researchers studied twenty-five (23 men, two women) well-trained cyclists for 12-weeks. The scientists asked the participants to perform six 40-minute individual time trials (40-ITTs) with a minimum of 48 hours of rest between each.
Researchers used 14 days of resting HRV measurements for each cyclist to determine individual smallest worthwhile change windows (SWC). The scientists considered daily HRVs that fell outside the SWC window as indicators of meaningful physiological or psychological status changes.
The variations induced by training or daily stress were deemed abnormal for the purposes of the study. The subjects checked their morning HRV daily to determine where they fell.
The subjects performed the 40-ITTs virtually using their bike and trainer without the aid of virtual cycling platforms or programs. The cyclists performed three trials after a normal HRV and three after an abnormal status. The participants did not alter their training or begin a new program during the study period.
The researchers measured total distance, peak and average speed, and peak and average power (watts). The results were interesting and not what they hypothesized—that HRV was related to day-of performance.
The Results: Short-Term HRV Has No Effect on Cycling Performance
The researchers discovered that day-of HRV readings have no significant influence on the average performance metrics of a 40-ITT in trained cyclists. The data recorded within normal and outside normal HRV for distance, peak and average heart rate, average speed, and average power were almost the same. In addition, the researchers saw little effect on psychological indicators, like perceived exertion.
The scientists did find a statistically significant decrease in peak power and peak speed during times of abnormal HRV. It did not impact the average speed or distances covered during the subject’s 40-ITTs.
Daily HRV Readings May be Valuable to Virtual Cyclists
Compelling to note, cyclists may experience greater abnormal HRV related performance changes in peak power-based events than during endurance events. This information is good to know for esports enthusiasts, where most virtual races are the equivalent of Criteriums on the road.
Daily monitoring of HRV is valuable in predicting an athlete’s race day peak power and speed. However, according to the study, a short-term abnormal HRV status doesn’t compromise average cycling performance or perception of effort.
As a whole, the researcher’s determination supports the belief that temporary shifts in Autonomic Nervous System activity do not play a significant role in performance. Instead, it better serves the athlete to track HRV data over an extended period and correlate it with training load and subjective feelings.
HRV variability is a powerful tool—one of the few data points directly reflecting how our nervous system is reacting at the moment. As science indicates and athlete experience upholds, using HRV to make unilateral race time decisions is not the most effective course of action.
Know your trends, heed your coach’s advice, and listen to what your body tells you. Use HRV to point you in the right direction, but don’t be afraid to keep your focus down the road.
Are you an eracer and do you use daily HRV as a guide for your training and racing? Comment below! Your fellow virtual cyclists are interested in your experience.
For more helpful cycling-related information check out the Training & Performance page of 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, Endurance.biz, and Bicycling. Chris is co-host of The Virtual Velo Podcast, too!