The human heart is perhaps the most sophisticated machine on this planet. However, it is a delicate masterpiece that needs your attention, care and maintenance. At present, cardiovascular diseases (CVD) are one of the leading causes of death globally. The World Health Organization has reported almost 17.9 million deaths from CVDs in 2019, which comprises almost 32 percent of the total global deaths. Without a doubt, it has become imperative to keep a constant and vigilant eye on the heart. Several parameters like chronic stress, inactivity and even over-exercise can affect your heart rate variability (HRV). Let us first understand what HRV is.
What is heart rate variability?
The human heart pumps blood to the brain cells against the pull of gravity as well as all the way to the toes that are the farthest from it. The heart has the ability to increase or moderate its functioning to meet the body’s demand—for example, it becomes calm when you are asleep and starts thumping when you are working out or extremely anxious. Heart rate is the measure of how many times the heart beats per minute, while HRV is the duration or interval between each beat. HRV is quite literally the time interval between consecutive heartbeats in milliseconds.
This is usually measured in milliseconds. The normal heart rate ranges from 60 to 100 beats per minute. However, within that minute, some heartbeats will have a 0.8-second gap, while others could have a gap of up to 1.4 seconds. This HRV is a design aspect of the heart and can be used to our advantage, especially during workouts. A higher HRV is better, as it suggests a good pace between the heartbeats. A greater variability between heartbeats or a higher HRV indicates that your body has a strong capability to endure stress or is recovering well from stress. HRV is affected by various factors including overall metabolism, workout regimens, stress, diet, age, gender, genetics, habits and sleep patterns, to name a few. Understanding HRV is important to understand your body’s readiness to perform at and maintain high levels of fitness and overall well-being.
ANS translates into autonomic, meaning not controlled by the person. The ANS manages body actions such as heart rate, blood flow, digestion, etc., It is like a set of wires that light up a bulb (heart rate) at different intensities, depending on the amount of brightness outside (body activity).
HRV arises from the two opposing branches of the nervous system – sympathetic and parasympathetic concurrently sending signals to your heart. The sympathetic branch triggers stress hormone production. It also raises the heart’s contraction rate and force (cardiac output) and decreases HRV, which is required during physically or mentally strenuous situations. The parasympathetic branch, on the other hand, reduces the heart rate and increases HRV to reinstate homeostasis after the perceived stress has passed.
Five ways to train better by understanding and using HRV
To get the most out of your workouts, here are five ways you can better understand HRV and maximize on it:
Understand your baseline and plot a workout trend
With technological advancements, people now have access to apps that monitor everything from sleep patterns to breathing to heart rates. We can easily record these parameters and understand our body better to design a workout that would suit us. Our workout regimens have evolved over the last couple of decades from running, cycling and swimming to high-intensity aerobics and high-intensity interval training (or HIIT). The body’s adaptability is simply amazing, and as anybody can notice, the extent to which one can work out constantly increases when the body’s capacity is regularly and constantly stretched. While 10 squats may have been difficult to begin with, over a period of time, one can do up to 50 squats. This also affects the body’s HRV, which increases over a period of time to “compensate” for the additional load on it. The HRV measure is a reflection of training readiness. Studies show that HRV can be a robust forecaster of successful training adaptation.
Measure HRV around the same time every day to plot a trend. Begin by recording your HRV and establishing a baseline as to what is normal for your body and your lifestyle habits. Record your HRV for two weeks and see how the 14-day moving average looks like. This will help achieve a realistic baseline. Any changes in terms of increase or decrease will get averaged out to give a near-normal HRV with this method. In addition, other parameters like sleep pattern and activity levels should also be taken into account to see if they are causing abnormal variations in HRV. This multi-parameter approach will help establish a proper baseline and you can then plan your workout accordingly.
HRV has two phases in relation to the ANS: a flight-or-fight mode and a rest-and-digest mode. The first is to act quickly by responding to a particular stressful (physiological, not psychological stress) event, while the second is to gradually prepare the body for long-term enduring events, thereby helping it get accustomed to building muscles and overall immunity and strength.
It’s you vs you
HRV is a personalised metric. There is no gold standard for HRV. As we mentioned earlier, each body is different in terms of physiology and will respond differently to different situations. While one person may be able to maintain a high HRV with no effort, someone else may need longer time and effort to achieve a higher HRV. It is best not to try and emulate someone else but listen to your body and see how you can let it adapt. Give it some time before pushing your workout levels by multiple notches.
While the HRV monitor will definitely tell you about HRV in itself, do also take into account other parameters, as discussed above, to ensure you are taking a multi-parameter approach. Sleep patterns, stress levels (psychological), food habits, health conditions, diet, genetics, and more, are all contributors. Your HRV is absolutely yours; be gentle with your body and your heart, and it will serve you well in the long run.
Research suggests HRV declines with age. It is usually higher in males than in females, in athletes than in non-athletes. Although there are many people who are in great shape and yet have a comparatively lower HRV contributing to the idea of HRV as an individual metric. Thus, it is very essential to understand your HRV numbers and plan your workout routine around that.
The absolute HRV value is not of as much significance but its directional trend reveals insights about inflammation in the body.
Figure out ideal workout days
Once you have established a baseline HRV and know what will work for you to achieve a higher HRV, use this to maximize your workout. As you may have noticed , there are some days you are raring to get out of bed for some real action. Those days are probably your good HRV days, and you can capitalize on them to do vigorous workouts. While there are established average heart-rates (72 is considered normal, in case you were wondering), there is no established average for HRV. In most people, the body tends to fully recover from the previous day’s training by the following morning. If this has not happened due to various reasons (poor diet, poor sleep, muscle fatigue, etc.), then you will not be able to perform to your full ability that particular day. So, make sure your HRV is back to normal before you plan your next workout. To give you an example, it is like stretching a rubber band to a certain length but not crossing the limit, so that it never loses its elasticity. Let the rubber band regain its form, and then stretch it again, thus ensuring it is not stretched beyond capacity.
Know when to slow down
Various randomized trials have proven the correlation between HRV and recovery. When your HRV is low, make sure you allow your body time for recovery. Check if you require an additional day of rest before stretching your body to its full capacity during workouts. Inadequate recovery can lead to defective performance. Tracking your HRV can also disclose a wealth of health information like the quality of your sleep. Pairing your HRV measure with your sleep data can help you change your sleep patterns, workout routine and even stress management tactics. It can help you gauge the quality of your recovery. Elevated levels of stress and poor sleep can lower your heart rate variability. Research suggests that HRV is a reliable statistic to screen individuals for potential referral to sleep labs for diagnosis of sleep disorders. Emotional stressors can translate into a reduced capacity for enduring training stress leading to a rapid fall in HRV.
It’s a long game
Understand the long-term effects of optimizing HRV. Don’t push your body to its limits in one go. Give it some time, arrive at your average HRV and build your workout pattern around it. While you may not be able to achieve a good workout on a particular day, over a period of time, your adaptability will improve and your body will stretch its limits to ensure that your workout goals are met. Too much, too fast is not a mantra that works when it comes to the heart.
HRV or heart rate variability is the duration or interval between each heartbeat. Monitoring your HRV helps the heart vocalize when you need to stop, relax, breathe and sleep. From helping to personalize your workouts to raising an alarm on your stress levels to highlighting your sleep patterns, knowing and understanding your HRV will help you live a healthier and fuller life.
Disclaimer:The contents of this article are for general information and educational purposes only. It neither provides any medical advice nor intends to substitute professional medical opinion on the treatment, diagnosis, prevention or alleviation of any disease, disorder or disability. Always consult with your doctor or qualified healthcare professional about your health condition and/or concerns and before undertaking a new healthcare regimen including making any dietary or lifestyle changes.