Kurt Salquist

Heart Rate Variability: Improving your fitness by training smarter, not harder.

Overtraining can be seriously detrimental to an athlete’s progress towards their goals. However, identifying when you are going too hard and understanding when it is appropriate to take some time off or scale back can be very challenging. I discussed some signs and symptoms in the last newsletter, but a more tangible biomarker that has been utilized is Heart Rate Variability (HRV). Part two of this two part series will encompass a bit about Heart Rate Variability-what it is, how it has been researched and used thus far, and how it can be applied to your training.

HRV is the variation in intervals between heartbeats. When we take our heart rate, we are just counting the beats we hear/feel TOTAL in a given amount of time. HRV records how those beats vary from one to the next. If your heart beats with equal time in between each pulse, like a metronome, you have low heart rate variability. If your heart beats with a variation of time between beats, you have a high variability. You WANT a high variability. You do NOT want a metronome-like beating heart. Huh? If you are like me, this was very counterintuitive.  It turns out that a heart with such a set rhythm is too robotic. It is less natural. Our hearts work best when pumping on demand, as needed. Cardiac specialists actually use HRV to track the health and recovery of their patients. A low HRV is associated with the development of coronary heart disease and metabolic syndrome (diabetes, hypertension, high cholesterol, large waist circumference). There has been a connection with low HRV in people that have had heart attacks and a heightened risk of dying in the following three years after the attack. A high HRV has been associated with healthy longevity, relatively free of morbidity.

Let’s look at the body in just a little more detail to further your understanding of HRV. I’ll try not to get too nitty gritty, but a well-rounded understanding will be imperative to appropriate application of the information. For starters, we will address the two main Autonomic Nervous Systems of the body. These are the non-voluntary systems: sympathetic and parasympathetic.

  • Sympathetic Nervous System: nervous system that gets activated during times of stress. This is commonly referred to as the “fight or flight” system.
  • Parasympathetic Nervous System: counters the body’s response to the sympathetic. It calms your body down and brings it back to a state of rest and recovery, commonly referred to as the “rest and digest” system

These two systems work with each other, not against.  If the PNS is strongly activated, you will see a high level of variability in heart rate. Conversely, if the SNS is dominating the PNS will be blunted and variability will be low. Knowing this helps you see how your body is responding to the cumulative demand placed on your neuroendocrine system to maintain balance. Another consideration is how HRV changes with aerobic vs anaerobic athletes. HRV training is most researched and used with aerobic athletes, as it is a reflection of the cardiovascular autonomic nervous system. This system is the one that is highly utilized in aerobic athletes, vs athletes that primarily use the anaerobic system, such as people that focus only on weight lifting without exhibiting much demand on their heart for more than a few seconds. HRV doesn’t reflect muscle soreness/damage, another difference between the two types of training.

With these associations in mind, how can we apply HRV to training and athletics?  Generally speaking, when a person’s HRV is high, training with higher intensity/volume can elicit greater training adaptations. However, an increasing HRV trend throughout training is not always great. Several studies have shown increased HRV trends in overtrained athletes. When they tapered off, their HRV came down closer to baseline. Low HRV is commonly thought to indicate fatigue from training or competing. Your body sends out an alarm with overload training where your heart rate increases and HRV decreases. Increased heart rate is a response of your sympathetic nervous system (flight or fight). A person needs sufficient recovery time to bring the HRV back to baseline. HRV may be suppressed up to 72 hours after a challenging training day. If you do not get enough rest and recovery, this delays the time of which the HRV gets back to baseline, and will affect performance if the overload period is sustained. I want to reiterate that a low HRV score is not always a red flag to back off training, nor is a high HRV score an indicator to get after it. The best use of HRV is to note trends using yourself as the test subject and recording over a period of time what your HRV scores tend to do while also considering other variables. As with all research, ideally you are limiting other variables while recording and analyzing your HRV. This tool is a global marker of stressors-physical, mental, or chemical which means that variation can be brought on by other things.

So how do you measure HRV and what other factors do you need to consider?  There are a few applications you can download on your smartphone that work with a heart rate monitor. Usually tested upon waking, you can put on your blue tooth compatible heart rate monitor and test your HRV through the application. It is really important to maintain consistency with your testing-time, how you breathe, how you are sitting or standing, etc. Popular applications include:

  • Elite HRV
  • HRV4 Training
  • Tink
  • Bioforce

Score may be lowered by:

  • Poor sleep/lack of sleep
  • Alcohol
  • stresses-work, money, social

It is also helpful to know what activities help activate the SNS or the PNS. Remember, balance and your ability to recover from the stress from the sympathetic demand is the focus of recovery. We want to get back out and train but don’t want to when we are overly stressed. So implementing PNS-activating activities can help balance this out.

Let me know what application you choose and what you think! Please feel free to ask questions and we will address them in our Q and A section of the next newsletter. I know this was a lot of information so I am happy to answer questions, concerns, and considerations on the topic of HRV training.

Recreational sports
Martial arts & wrestling
Powerlifting, Olympic lifting, strongman,
Yoga (unless you are experienced, yoga can be very difficult and therefore trigger a sympathetic response)

Diaphragmatic breathing
Skillful play- randomized fun activity that is not physically taxing
Myofascial release


Let me know what application you choose and what you think! Please feel free to ask questions and we will address them in our Q and A section of the next newsletter. I know this was a lot of information so I am happy to answer questions, concerns, and considerations on the topic of HRV training.

Read more:

Have You Checked Your Heart Rate Variability Lately?

Interpreting HRV Trends in Athletes: High Isn’t Always Good and Low Isn’t Always Bad


Therese Martinez, MS, RD, CPT

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