Most people are aware that “too much” stress is a significant risk factor in the progression of physical illnesses including cancer. What is far less clear is how to determine if your stress level is within acceptable limits or not. Whether the guided meditation, yoga, or deep breathing that you’ve committed to regularly doing is enough to offset the wear and tear of your everyday life? Recognizing how “stressed-out” you are is tricky if the mental state you’re is all too familiar. Though the problem of stress is commonly written about, the issue of its measurement is rarely addressed.
Heart-Rate Variability and Stress
One way to objectively begin to sort out how your body answers this question is to measure your Heart-Rate Variability (HRV). HRV is literally a measure of the beat-to-beat variation in time between heartbeats. For example, if your heart rate is 60 beats per minute, this doesn’t mean that your heart is beating once every second. Within that minute, there may be 0.8 seconds between two beats, .9 seconds between two others and 1.1 seconds between two more. So what does HRV say about stress level?
HRV can be thought of as a marker of our bodies’ biochemical response to acute stress and the method by which it returns to biochemical balance or allostasis. HRV takes the pulse of your nervous system. It’s a biomarker of the impact that making complex decisions, daily worries, the lingering impact of emotional trauma - has on your health and well-being
A high HRV means there’s a good amount of variation between your heartbeats. It typically means that the two components of your Autonomic Nervous System (ANS), the parasympathetic and the sympathetic nervous systems, can react to a demand in the environment (a stressful situation) and then recalibrate once the demand passes.
Low HRV means that there is little variability in the space between your heartbeats and this is suggestive that one branch of your ANS is more dominant (usually the sympathetic nervous system) and is sending stronger signals to your heart than the other branch. A chronic low HRV indicates your body is working too hard for some reason which leaves fewer resources available to dedicate towards other physiological activities.
HRV and Cancer
So what does HRV mean where cancer is concerned? Research published in mainstream journals can answer this question.
First: Cancer patients with a high HRV have been found to live longer compared to cancer patients with a low HRV (Zhou et al., 2016). A meta-analysis of 19 studies (based on humans not animals) found a high HRV to be associated with less progression of disease and better outcome across many cancer types (Kloter, 2018. Frontiers in Physiology).
Second: HRV was shown to be significantly lower in patients with a Stage III/IV diagnosis compared to patients whose cancer had not metastasized.
Third: Cancer patients with lower HRV have been found to have significantly higher tumor marker levels.
What’s the mechanism?: The mechanism suspected to underlie these findings has to do with vagal nerve activity as it relates to the immune system. Another hypothesis suggests that the association between lower HRV and tumor growth occurs through three pathways, i.e., inflammation, oxidative stress, and sympathetic nerve activation.( De Couck et al. (2013),
How Do You Check Your Heart-Rate Variability?
The first step is to determine what your baseline HRV is and begin to track its changes so you can see how it’s trending. Over the past few years, several companies have launched apps and heart rate monitors that do something similar to EKGs. The gold standard is a chest strap heart monitor but easiest and cheapest is to get a Fit Bit or Apple Watch and download a free app to analyze the collected data. There are also more professional athlete options such as Polar and Whoop. The set up I like best comes from HeartMath. The best time to check your HRV is in the mornings after you wake up, a few times a week, and track for changes as you incorporate changes to your lifestyle.
Once you know where you stand, only then can you craft an HRV strategy.
The good news is that there’s something that you can do if your HRV is low. There are several Lifestyle Management action steps that you can take that can help you gain more variability in this very important biomarker. Here are 5 things you might do and there are many more:
Increase Your Social Interaction - Your vagus nerve activity is associated with social interaction and decreased stress. So spend more time with friends to increase your HRV.
Meditate: A 2013 study found that people who did even five minutes of meditation daily for 10 days had a better HRV compared with those who didn't meditate.
Do HRV Biofeedback. HRV-B is a biofeedback approach that gives you real time feedback about your (HRV) as a means of teaching you how to breathe in a specific, therapeutic manner.
Take a Magnesium Supplement: Studies show that long-term supplementation increases HRV (not medical advice).
Up Your Sleep: Poor sleep quality leads to a lower HRV pattern (sympathetic over parasympathetic dominance).
The Bottom Line
HRV measurements can help create more awareness of how you live and think, and how your behavior affects your nervous system and bodily functions. Think of HRV not as an absolute measure of your stress profile but as another preventive tool. The science strongly suggests that it could be a useful measure in terms of your cancer risk factor profile.
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Kloter E, Barrueto K, Klein SD, Scholkmann F, Wolf U. Heart Rate Variability as a Prognostic Factor for Cancer Survival - A Systematic Review. Front Physiol. 2018;9:623. Published 2018 May 29. doi:10.3389/fphys.2018.00623
Kim HG, Cheon EJ, Bai DS, Lee YH, Koo BH. Stress and Heart Rate Variability: A Meta-Analysis and Review of the Literature. Psychiatry Investig. 2018;15(3):235-245. doi:10.30773/pi.2017.08.17