Heart rate variability, otherwise known as HRV, is a measurement of the autonomic nervous system, a network of nerves that automatically regulate unconscious tasks like breathing and heartbeat. In other words, HRV gives us insight into how balanced the sympathetic and parasympathetic branches of our nervous system are. By balancing these two systems, the autonomic nervous system allows us to properly respond to daily stressors.
A healthy heart is not meant to beat regularly, in fact, it changes rhythm with each beat, and it is this variation, measured in milliseconds, between each beat that is known as HRV. We use HRV data to understand the heart’s ability to respond to different situations.
What might this look like? Well, your HRV reading can demonstrate your body’s reaction to stressors and illness and determine how well your recovery status and general well-being are. When our parasympathetic nervous system, the “rest and digest” branch, tells our heart to slow down, our HRV number goes up. This is because there is more room for variability between beats and this is what we want! Alternatively, when our “fight and flight” branch, otherwise known as our sympathetic nervous system, tells our heart to speed up, then there is less space for variability between beats, thereby lowering our HRV score.
When looking at your own HRV, it is important to understand that the number is unique to you. There is no “optimal range.” A “high” or “low” HRV is relative for each person, so one must never compare. Some clients I see have quite steady HRVs, while others might have more fluctuations. Some individuals are in the low 30s while others are in the 100s, and both can be optimal numbers for each. The most important metric is your own. I advise clients to measure their HRV with whichever wearable they choose and use that number to establish a baseline over a couple of weeks. Once the baseline is established, the goal is to try to raise your own HRV number by modifying certain variables that are within your control.
It is important to understand that there are variables that might negatively affect our HRV that are out of our control. Factors such as age, gender, illness, and, especially for women, our hormone cycles. Yes, our HRV can change significantly depending on where we are in our cycle.
But there are plenty of factors that are in our control when we want to improve our number, and these include nutrition and lifestyle behaviors. For example, when it comes to nutrition, we may want to avoid a late or heavy dinnertime meal. Perhaps we want to pay attention to how alcohol affects our HRV number. Maybe you can get by with one glass of wine with dinner, but anything more, and your HRV trends down considerably.
We also want to think about our sleep hygiene routine. Are electronics switched off before bedtime? Is the temperature of the bedroom ideal for sleep? Is the room sufficiently dark?
What about physical activity? Did you get enough movement in your day, or did you push yourself too much?
How are you dealing with stressors? Can you manage your stress, with meditation or breathwork at night to see if that helps change your HRV number?
Your daily HRV number can provide information as to how to go about your day. If one morning you notice your nightly HRV trended down, you might consider forgoing a challenging workout that day and focus more on recovery or stress management. You might, for example, consider adding in a breathwork or meditation session.
Looking at HRV trends over a month at a time can also reveal how recent changes in one’s life are affecting your nervous system. Have you recently changed jobs, begun training for a marathon, or welcomed a new baby? Has your HRV trended up or down over the last month because of these new changes? Ultimately, when looking at HRV, you want to watch for trends. This will provide you with the most insight into whether your lifestyle choices work for or against you.
Heart rate variability is a great health marker to track when trying to optimize our health. A balanced and strong nervous system is integral to how we respond to our daily stressors, stressors that are often beyond our control. Using a wearable to track your HRV and making nutrition and lifestyle changes will help you get closer to your goal of optimal health.
