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By Mike Seilo

NSCA CSCS, USAWSP, BioForce Conditioning Certification

Fri Jan 03, 2020


Heart Rate Variability or HRV measurers and tracks an athlete’s readiness and fatigue. HRV measurers how well someone has recovered or not from the accumulation of physical and mental stress. This data can provide the missing link to optimizing an individual’s training program, determining when to train and when to rest.

The technology of Heart Rate Variability (HRV) was originally developed by the Russian Space program back in the 1960’s to measure how prepared their cosmonauts were for space travel. HRV was then picked up and used by the medical community to assess the risk of patients who had suffered heart attacks. Professional athletic teams and government run Olympic programs also started to use HRV to monitor the readiness of their athletes. Up until recently, this technology has been very expensive and only professional sports programs, medical institutions and governments could afford to use Heart Rate Variability.

Heart Rate Variability measurers the recovery rate of an individual’s autonomic nervous system. The autonomic nervous system regulates a myriad of tasks. This branch of the nervous system communicates with organs and controls actions such as digestion, salivation, blood pressure, heart rate, and many others. Most of the communication occurring in this branch is unconscious and automatic, which is why it is called the autonomic nervous system and it is highly responsive to stress. The goal of the autonomic nervous system is to maintain homeostasis (balance of systems in the body}, and it does this by utilizing its two subsystems – the sympathetic nervous system and the parasympathetic nervous system.

The sympathetic nervous system acts to speed up certain processes within the body. This system is responsible for the “fight or flight” response that occurs when a human is faced with a stressful event. The sympathetic system is responsible for raising our heart rate at the onset of a stressor, increasing blood pressure, and dumping glucose into the blood to fuel activity.

In contrast, the parasympathetic nervous system works in opposition, effectively slowing everything back down. The decrease of heart rate and storage of nutrients are two of the many activities mediated by this system.

The inter play between the sympathetic and parasympathetic systems to restore the body back to its normal levels is the main goal of Homeostasis. Homeostasis is maintained through a physiological balancing act between these two sub systems. For an athlete, intense training presents a large stressor to the body, invoking a strong sympathetic response to meet the increased metabolic demands. Post-workout, as the sympathetic tone subsides, the parasympathetic system becomes facilitated and drives the rest and repair necessary to get things back to normal. Ideally, these two systems remain balanced in their efforts, each ramping up and down as needed to restore Homeostasis.

There seems to be a misconception by some that the heart, as it beats away in the ribcage, acts like a metronome, adhering to a strict cadence always. The heart beats through a wide spectrum of rhythms throughout the day – these beat-to-beat variations are what the science of heart rate variability is targeting. Given that the cardiovascular system is largely controlled through the actions of the autonomic nervous system, analysis of HRV provides some great insight into these control mechanisms. For example, when the body is battling a stressor, the variation between beats tends to be lower (i.e., less heart rate variability) and it assumes a more metronome-like quality. This situation is indicative of higher sympathetic nervous system activity – the “fight-or-flight” response is ramped up to handle the homeostatic challenge. Conversely, as the variability of the heart rate increases, the body assumes more of a rest-and-repair status, indicating increased activity of the parasympathetic nervous system.

Specific to athletes, who want strong sympathetic nervous system activity during their training to fuel the highest levels of performance, but also want to be able to shut that system off so they can effectively recover for a subsequent session. To use an automobile for comparison, it’s hard to slow down if you can’t take your foot off the gas. Constant activation of the sympathetic nervous system creates an unfavorable shift in the sympathetic and parasympathetic balance, greatly increasing the likelihood of fatigue and overtraining. One of the easiest ways to determine whether these two systems are doing their jobs and homeostasis is being achieved, is through the daily use of Heart Rate Variability technology.

Until recently the training process has been approached from the outside in. This means that a training program is designed for an individual without having any idea of how well it is working or not working. With Heart Rate Variability the process of training has been reversed. Instead of designing programs from the outside in and hoping for the best, they can now be designed from the inside out to meet exactly what the individual needs on a given day. This saves valuable time and energy and allows the goal to be met sooner.

Whether you are training for triathlons, marathons, or use endurance sports for your own personal fitness, Heart Rate Variability can provide the necessary guidance through data to help you work smarter and more efficient.  It tells you how well you have recovered from your last workout and will help you optimize your training while maximizing your results. This information is very valuable because it allows you to adjust the intensity of each training session so that you can get the most out of your training and not over or under train.  Train smarter not harder.  


Elmore, G. (2018, October).  Incorporating Training Load Monitoring into Fitness Programming:  A Review of Practical Tools for Fitness Providers. NSCA Personal Training Quarterly

Jamieson, J. (2012).  The Ultimate Guide to HRV Training.  Kirkland, WA: Bioforce HRV Precision Performance

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