Heart rate variability (HRV) guided training has been proven effective in improving athletic performance. The key to HRV-guided training is to perform moderate and higher intensity workouts only when the HRV score is within or above the normal range. Lower intensity workouts or rest days are prescribed when the HRV score is below the normal range. The normal range is defined on an individual basis and is established over several days. In the Kubios HRV Readiness index, the normal range is established over the past 3 months.
Heart rate variability monitoring for athletes
Heart rate variability (HRV) reflects fluctuations in the intervals between consecutive heartbeats, providing insight into cardiac autonomic function and overall physiological state. Endurance athletes typically demonstrate superior cardiac autonomic function compared to non-athletes, characterized by lower resting heart rates and greater resting HRV. Gradual increases in resting HRV have been linked to improved aerobic fitness and performance [1].
The availability and use of HRV metrics have increased due to the ease of access to monitoring tools. Athletes, coaches, and sports medicine staff commonly collect HRV data, with daily resting HRV measurements taken in the morning often recommended. Selecting the appropriate HRV parameter for monitoring athletes’ physiological state is crucial. RMSSD is the most commonly used parameter because it reflects cardiac vagal regulation, is not affected by respiratory rate (unlike HF power), and is simple to calculate. However, RMSSD has a limitation, where reduced HRV can sometimes be observed despite a low resting HR due to HRV saturation [2]. This limitation can be addressed by using the PNS index, which accounts for resting heart rate.
How training affects HRV
The impact of training on resting HRV is individual and influenced by factors such as training status, cardiorespiratory fitness, age, and sex. Regular aerobic training typically increases HRV in athletes. However, increased exercise duration can elevate the overall training load and acutely decrease daily HRV. Exercise intensity, on the other hand, impacts HRV scores either immediately or the day after exercise. [3]
Cardiac-autonomic functioning, assessed via daily resting HRV measurements, serves as a non-invasive marker of acute and chronic adaptation to endurance exercise. In the short term (within 48 hours after exercise), HRV recovery to baseline coincides with the restoration of thermoregulatory, metabolic, hemodynamic, and fluid-balance processes disrupted by physical exertion. Long-term HRV profiles reflecting higher and/or more stable resting values are associated with greater improvements in post-intervention fitness outcomes among sedentary, moderately-trained, highly-trained, and clinical populations. [4]
HRV-guided training protocol
HRV-guided training protocols involve tailoring workout intensity based on daily heart rate variability readings to optimize performance and recovery. When the HRV score is within or above the athlete’s normal range, moderate to high-intensity workouts are recommended. Conversely, when the HRV score is below the normal range, lower intensity activities or rest days are advised. This personalized approach helps balance training stress and recovery, minimizing the risk of overtraining, and enhancing overall athletic performance. The Kubios HRV app provides validated means for daily HRV measurement and can be used free of charge by athletes to assess daily recovery status, ensuring effective HRV-guided training.
An example HRV-guided training protocol is presented in the figure below. The basic idea is to lower the training intensity whenever the daily HRV score decreases and not to allow more than two consecutive high-intensity exercises or rest days.
Figure: HRV-guided training scheme (redrawn from [5]).
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Effectiveness of HRV-guided training
HRV-guided training has been validated against predefined training in several studies [4], [6], [7]. These studies have shown that HRV-guided training is effective, associated with improved submaximal performance, better or similar overall performance and physical fitness, and fewer non-responders. Additionally, the benefits of HRV-guided training are typically achieved with a reduced amount of moderate and/or high-intensity training.
In summary, HRV-guided training is an accessible and individualized exercise prescription strategy that may be more effective than predefined training for maintaining and improving performance, with a lower likelihood of negative responses. Daily monitoring of HRV allows athletes to adjust their training day-by-day and observe changes in their physiological state. With the Kubios HRV Team Readiness dashboard, coaches can also leverage HRV data to tailor training programs for their athletes. Gradual increases in average HRV correspond with improved overall physiological performance, aerobic fitness, high functional state, readiness to train, and recovery ability. Conversely, decreasing HRV has been associated with maladaptive states, including illness, non-functional overtraining, and, in the worst case, overtraining.
Frequently Asked Question (FAQ)
What is HRV-guided training?
HRV-guided training involves adjusting workout intensity based on daily heart rate variability (HRV) readings. When HRV scores are within or above the normal range, higher intensity workouts are recommended. Lower intensity activities or rest days are advised when HRV scores are below the normal range. This personalized approach helps optimize performance and recovery.
How does HRV monitoring benefit athletes?
HRV monitoring provides insights into an athlete’s cardiac autonomic function and overall physiological state. By tracking HRV daily, athletes can tailor their training to improve performance, prevent overtraining, and enhance recovery, leading to better athletic outcomes.
What is the normal range for HRV in HRV-guided training?
The normal HRV range is individually defined and established over several days of measurements. In the Kubios HRV software, this range is calculated based on data collected over the past 3 months, providing a personalized baseline for readiness score assessment.
Who can benefit from HRV-guided training?
HRV-guided training can benefit a wide range of individuals, including endurance athletes, fitness enthusiasts, and recreational exercisers. Athletes seeking to optimize their performance and recovery will find HRV-guided training particularly useful for preventing overtraining and improving overall fitness. Coaches and sports medicine professionals can also leverage HRV data to tailor training programs for their athletes.
How effective is HRV-guided training compared to predefined training?
Studies have shown that HRV-guided training is effective in improving submaximal performance, overall physical fitness, and reducing the number of non-responders. It often achieves these benefits with a reduced amount of moderate- and high-intensity training, making it a more efficient and individualized approach to training.
References
- C.J. Lundstrom, N.A. Foreman, and G. Biltz. Practices and applications of heart rate variability monitoring in endurance athletes. Int J Sports Med, 44:9-19, 2023.
- D.J. Plews, P.B. Laursen, J. Stanley, A.E. Kilding, and M. Buchheit. Training adaptation and heart rate variability in elite endurance athletes: opening the door to effective monitoring. Sports Med, 43:773-781, 2013.
- M. Buchheit. Monitoring training status with HR measures: do all roads lead to Rome? Front Physiol, 5(73):1-19, 2014.
- A. Manresa-Rocamora, J.M. Sarabia, A. Javaloyes, A.A. Flatt, and M. Moya-Ramón. Heart rate variability-guided training for enhancing cardiac-vagal modulation, aerobic fitness, and endurance performance: a methodological systematic review with meta-analysis. Int J Environ Res Public Health, 18(10299):1-22, 2021.
- A.M. Kiviniemi, A.J. Hautala, H. Kinnunen, and M. Tulppo. Endurance training guided individually by daily heart rate variability measurements. Eur J Appl Physiol, 101:743-751, 2007.
- A. Granero-Gallegos, A. González-Quílez, D. Plews, and M. Carrasco-Poyatos. HRV-based training for improving VO2max in endurance athletes. A Systematic review with meta-analysis. Int J Environ Res Public Health, 17(7999):1-21, 2020.
- P. Düking, C. Zinner, K. Trabelsi, J.L. Reed, H.-C. Holmber, P. Kunz, and B. Sperlich. Monitoring and adapting endurance training on the basis of heart rate variability monitored by wearable technologies: A systematic review with meta-analysis. J Sci Med Sport, 24:1180-1192, 2021.