A healthy heart beats anywhere from 60 to 100 times per minute. While things like age and gender can affect this range, significant variations are often caused by disease, mental stress, inactivity, and injury. This kind of change is known as heart rate variability or HRV.
Below, we'll explore different ways to improve HRV, from getting enough sleep to monitoring your hydration, and more.
HRV refers to slight fluctuations in the heart rate rhythm that may indicate psychological and physiological stressors on the body. More specifically, HRV is the measure of the time between consecutive heartbeats. These irregularities are usually very small (fraction of a second long) and require specialized devices for detection. Your heart may appear to be beating regularly, but some variation exists and is considered normal.
As mentioned, heart rate variability can be found in healthy adults; however, it can also signify an underlying health issue, such as a heart condition, depression, or anxiety. At resting state, a higher HRV is indicative of better cardiovascular fitness while a lower HRV may indicate potential health problems.
Just like weight, steps, and calories, heart rate variability trends can also be tracked and utilized as a marker of your resilience and behavioral flexibility. Heart rate variability is one of the best objective metrics of training performance and recovery state.
The autonomic nervous system (ANS) controls the variation in heart rate. The ANS facilitates various physiological functions such as breathing, digestion, and blood pressure regulation. It is divided into the sympathetic nervous system (fight-or-flight response) and parasympathetic nervous system (rest-and-digest or relaxation response).
After receiving information, the ANS communicates with the brain, which then sends signals to the rest of the body, resulting in either a stimulated or rest state. The human body regularly processes stimuli like lack of sleep, emotional news, and delicious food in this way. However, persistent triggers such as an unhealthy diet, constant stress, dysfunctional relationships, and a sedentary lifestyle can disrupt the nervous system's ability to maintain a balance, leading the body's fight-or-flight response to go into overdrive.
HRV indicates disruptions in the sympathovagal balance. When the human body is in fight-or-flight mode (the sympathetic branch), the gap between consecutive heartbeats is lower. In contrast, it tends to be higher in a relaxed state (the parasympathetic branch).
Individuals with high HRV may possess better cardiovascular health, greater resilience to stress, and higher recovery potential.
Reduced HRV is associated with poor sleep quality, high-stress levels, and diseases like diabetes, cardiovascular disease, inflammation, obesity, and psychiatric problems. Low HRV has also been linked to high blood pressure and can be used to predict mortality in myocardial infarction patients and as an early warning signal for diabetic neuropathy.
With that, it's safe to say that HRV can be used to detect important changes in your body, your surroundings, and your mental state.
HRV increases when you take care of your body and your mind. Lifestyle changes, in particular, like increased mindfulness, quality sleep, deep breathing, cold showers, and regular exercise can improve HRV.
Research shows that increasing weekly alcohol consumption leads to decreased heart rate variability. Two small drinks per day have minimal effects on HRV, but when you double the amount, HRV reduces by 10%. If further doubled, HRV changes by 25% compared to HRV with no alcohol intake. These effects are also long-lasting, lasting up to four days after intake.
The underlying mechanism behind these observations is unclear, but it is proposed that alcohol might be negatively affecting the autonomic nervous system or the cardiac vagal tone. If you're a regular drinker and want to achieve a higher HRV, try to cut down your alcohol intake (to one glass) and only drink occasionally.
Consuming the right meals and nutrients is a key step towards improving your HRV. Research shows that higher omega-3 levels (through fish consumption) decrease heart rate and increase HRV. A Mediterranean diet, B-vitamins, probiotics, and polyphenols also raise HRV.
Intake of high trans-fat and high glycemic carbohydrate food sources is adversely associated with HRV.
Hydration is essential as water is an integral component of the cardiovascular system.
Lower levels of hydration result in a higher heart rate and decreased HRV. Less water means lower blood volume, which forces the heart to beat faster and work harder to maintain blood pressure.
An Irish proverb aptly states: "a good laugh and a long sleep are the best cures in the doctor's book."
When you fall asleep, your heart rate progressively slows down to the resting heart rate, resulting in an increased HRV score. The heart rate drops by almost 20-30% during deep sleep.
A 2017 sleep study demonstrated a link between higher heart rate and poor quality sleep, high sleep latency (time you take to fall asleep), and usage of sleep medications. It was concluded that poor sleep quality results in decreased HRV.
Sleeping at regular times has been shown to boost HRV by maintaining the circadian rhythm.
A patient's HRV can also be used for diagnosing sleeping disorders. Sleeping disorders that affect your sleep efficiency (ratio of time spent sleeping and time in bed) influence your HRV. For example, a 2014 research study reported an association between obstructive sleep apnea and lower HRV.
Your HRV can predict your sleep patterns as well. Increased heart rate variability when awake is associated with better sleep efficiency.
In a nutshell, a good night's sleep is as crucial as exercising or a healthy diet when it comes to heart health.
Exercise training, and at the right intensity, can improve your HRV. As your exercise intensity increases, your HRV decreases; this is applicable up to moderate-high intensity, after which an increase doesn't cause much HRV change.
A 2021 meta-analysis including 523 Type 2 diabetic patients concluded that exercise training elicited an increased HRV score, most likely through increased ANS activity.
Sedentary individuals can exercise a few times a week to elevate their HRV. On the other hand, active individuals can utilize wearable devices such as Fitbit and Whoop as a part of their training routine. These have HRV incorporated within their algorithm, which offers users instructions on how much to train and when to take a break.
A balance is needed so your body can reap the benefits of exercise without getting exhausted. Exercising below the first lactate threshold diminishes the body's inflammatory response (inflammation tends to lower the HRV). Therefore, low-intensity aerobic exercise is ideal for achieving a high HRV.
Natural sunlight helps regulate the circadian rhythm, which impacts your HRV. It is also needed to make vitamin D, which improves cardiac function.
Brief periods of exposure to cold temperatures (such as through ice baths and cold showers) increase the body's metabolic rate. Cold thermogenesis stimulates the vagus nerve (part of the parasympathetic system), which results in a significant increase in heart rate variability. Whole-body cryotherapy increases cardiac parasympathetic modulation and raises your HRV, just like exercise.
Breathing exercises can also impact your autonomic nervous system and, subsequently, your HRV.
A 2018 meta-analysis concluded that at least 60 minutes of yoga each week could substantially increase HRV and decrease the body's stress levels.
Resonance frequency breathing (slow, diaphragmatic breathing of 3-7 breaths per minute) elevates HRV by stimulating the parasympathetic nervous system. Deep breathing techniques (including mindfulness and mediation) also positively impact your heart rate variability.
Journaling is a non-invasive and effective tool to manage stress. Keeping a gratitude journal and spending time jotting down positive thoughts can reduce your stress and improve your HRV.
One study showed that narrative expressive writing helped decrease participants' heart rate and increase the HRV over 7.5 months.
Heart rate variability can be difficult to compare and standardize. Everyone has a unique HRV, which is why it can be challenging to measure it using simple charts or ranges. HRV trends show that it decreases with age and is impacted by the individual's gender and circadian rhythm. Not only this, but a normal person's HRV tends to change from day to day and season to season. Due to all these variables, it is not wise to compare your HRV to another person's as the comparison does not offer any concrete information.
By focusing on preventative medicine, dietary improvement, and healthy lifestyle habits, you can take charge of our health and avoid poor health outcomes.
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To improve your HRV during sleep, consider addressing the following factors: stress levels, bedtime routine, sleep environment, and sleep medication usage.
Almost all foods that constitute a healthy diet help increase HRV. A vegetarian diet, omega-3 fatty acid-rich foods like fish, fruits, green leafy vegetables, polyphenols, and B-vitamins contribute to high heart rate variability.
Simple walking, long-distance running, swimming, cycling, dancing are all examples of aerobic exercises that can help elevate heart rate variability.
Low HRV signifies poor overall health (particularly cardiac health) and is a reflection of unhealthy lifestyle practices. By sleeping well, exercising regularly, improving your diet and hydration, and reducing stress, you can improve your heart rate variability.