The Science of Stress, Heart Rate and Breathing

Normally, heart rate control is a balance between the two circuits of the Autonomic Nervous System – the Parasympathetic Nervous System and the Sympathetic Nervous System. You’ve probably heard of the Sympathetic Nervous System (SNS) before; it is often referred to as your “fight or flight” system. The Parasympathetic Nervous System (PSNS) is its counterpart, and can be thought of as the “rest and digest” system. Together, the PSNS and SNS work in all areas of the body to help you act, react, and recover.

In the heart, although both systems are always running at the same time, the PSNS is the main player in controlling heart rate at rest. Your heart rate starts to increase as the SNS gains more foothold. It is important to note that although SNS activation is normal, certain lifestyle choices we make can cause its activation to be unnatural and prolonged, which can have lasting consequences on our health.

The body responds to stress, worry, and anxiety in the same ways that it responds to fear and excitement – by activating the “fight or flight” system [1]. At a chemical level, your body releases a series of hormones that make you hyper-alert, focused, and energized, and this chemical cascade causes increased heart rate, respiratory rate, and perspiration. From an evolutionary standpoint, this is a system we needed in place for survival.

Consider the archetypal story of the man being chased by the bear. In the face of danger, he all of a sudden becomes hyper-aware of his surroundings and is able to forget everything – including injury, hunger, or thirst –to evade his predator. He suddenly becomes empowered with energy and strength and can do anything to escape. This is the essence of the evolved SNS, or “fight-or-flight” system. It’s how people have lifted cars when a loved one is trapped, or found the strength to run away from something chasing them, or even found the energy to sprint to the end zone and catch a ball when they were already expended. To your body, all these instances are examples of stress, and your body has evolved to prepare you to handle these stressful periods for your survival and to return you to safety.

So, if “stress” to the body is normal, why is our modern-day “stress” a bad thing? The issue today is that many of us are constantly stressed, worried, or anxious, and as a result, we are overworking our sympathetic nervous system, and not allowing this “return to safety”. One reason the SNS works so beautifully and can come to our rescue when we call is that it usually works in harmony with your “rest and digest” system. You need both, and studies today have shown that when you are under constant stress, your PSNS doesn’t resume control when the battle is done – because the battle is constant – and thus the influence of the PSNS decreases [2]. According to the Mayo Clinic, diminished PSNS activity at the mercy of increased SNS activity results in chronic health issues such as anxiety, depression, digestive problems, sleep problems, weight gain, memory impairment, and immune system depression [3]. In terms of the heart, the dire story of stress continues, as the effect of increased heart rate due to stress can lead to high blood pressure, irregular heart rhythms, higher cholesterol, and coronary artery disease [4].

How can we control this? Although it may seem scary to think about the effect that stress has on our body, especially because many of us can’t control the stress we are under, there is a silver lining. Because increased heart rate is an easy indicator of stress, we can combat our stress at a chemical level by recognizing when our heart rate is elevated, and then working to lower it. Fortunately, you hold the power to continuously monitor your heart rate on your wrist (your Basis watch, duh…), and you can therefore by an active player in reducing your stress.

Ok, cool, so how do we lower our heart rate? Remember that one effect of an increased heart rate is increased respiration, or breathing rate. In fact, when people are stressed, they tend to take faster, more shallow breaths, in accordance to increased heart rate. This actually differs from faster breathing due to increased heart rate from exercise, and it is this difference that makes breath control a powerful way to lower your heart rate and stress simultaneously. Basically, when you take faster, shallower breaths, are you getting rid of CO2 in the blood faster than normal [5]. This may seem like a good thing, but in fact, you need CO2 just as much as you need oxygen in your blood, and low levels of CO2 in your blood causes the pH of your blood to change, which can effect the function of your enzymes, organs, and muscles. Moreover, according to the NIH National Library of Medicine, low CO2 levels cause psychological effects, such as increased feelings of anxiety and fear, and once these feelings arise, your SNS activates, causing the “fight or flight” cycle to repeat [5]. So, CO2 is important, and controlling your breath as a way to restore and maintain your CO2 levels in your blood is an important way to reverse the stress cycle, and come back down to homeostasis.

All you gotta do, is breathe. Use your Basis watch to your advantage throughout the day. When you notice your heart rate is increased, take a moment to focus on your breath. Then, try the following exercises to decrease your breathing rate. According to the NIH National Center for Complementary and Alternative Medicine, the goal of these exercises is to decrease your heart rate and stress levels by stabilizing CO2 levels in your blood, maximizing oxygen levels in your blood, increasing oxygen saturation in cells, and lowering your blood pressure, all of which will lower the concentration of stress hormones in your body and activate the PSNS, or “rest and digest” system [1].

1. Deep Controlled Breathing. This technique involves deep and slow 10-second inhalation through the nose, followed by a slow and complete exhalation for 10 seconds. According to Dr. Fred Muench, a Professor at Columbia University Medical Center, taking fewer than 10 breaths per minute will start to engage the PSNS, which is associated with a recuperative state and will slow down your heart rate [6].

2. Diaphragmatic Breathing. The diaphragm is a large, thin dome-shaped muscle that fans out at the base of our lungs. It is our most efficient breathing muscle, but can be compromised in people with chronic stress. In fact, chronically stressed people tend to use their accessory muscles rather than their diaphragm to breathe. This hinders their ability to take deep breaths, which weakens the diaphragm and leads to rapid breaths. According to the University of Texas Counseling and Mental Health Center, employing diaphragmatic breathing acts to strengthen the diaphragm, decreasing the work of breathing and allowing a person to take normal breaths while maximizing the amount of oxygen that goes into the bloodstream [7]. Here is how it works:

• Sit comfortably with your head and neck relaxed and place one hand on your chest bone (in the center, below your throat), and the other hand on your stomach (in the center, on top of your belly button).

• Breathe in slowly through your nose so that the hand on your stomach moves, but not the hand on your chest.

• Exhale through your mouth and tighten your stomach muscles on the exhale, no chest-hand movement.

By getting more oxygen into your lungs and then into your bloodstream, your muscles will have more fuel and your heart will be able to beat slower and with less effort. In this way, you will interrupt the “fight or flight” response and trigger the body’s normal relaxation, or “rest and digest,” response [7]. When this occurs, the brain will send signals to the various hormone-producing organs, causing smaller amounts of stress hormones to be released [7]. This then enables the liver and kidneys regain control of the stress hormones in the blood stream, and the “fight or flight” response will decrease and ultimately stop.

3. Carotid Massage. There are times when you may reach a state of dire stress and anxiety – such as a panic attack. By the time you realize the attack, it seems that you are spiraling downward without rescue. This would be the time to employ the Carotid Massage, which in essence, is a physical way for you to activate the PSNS immediately, and will cause your heart rate, breathing rate, and blood pressure to decrease.

The carotid artery runs from your aorta and subclavian arteries, up either side of your neck, and to your brain. You know this artery, because you take your pulse from this artery. In fact, right at the area where you feel for your pulse, there is something called the “carotid baroreceptor”. These baroreceptors have nerve endings that act as sensors so that the brain can detect changes in blood pressure and respond accordingly [8]. The way that the brain responds is by either activating the SNS (if blood pressure is detected as low) or the PSNS (if the blood pressure is detected as high), with the overall goal being to restore normal blood pressure.

With this in mind, you can use the carotid massage as a way to “trick” your brain into thinking your blood pressure is high, which will cause it to activate the “rest and digest” response, and lower your heart rate.

In order to accomplish the Carotid Massage, take two fingers at your pulse, and gently massage in a circular motion. You should start to feel your body naturally slow down and relax [8].

Works Cited

[1] National Center for Complementary and Alternative Medicine (US). Relaxation Techniques for Health: An Introduction [Internet]. Health Information. Bethesda (MD): National Institutes of Health (US); 2011 Aug [cited 2013 Sept 21]; NIH Pub. No: D461. Available from: http://nccam.nih.gov/health/stress/relaxation.htm#status

[2] Vrijkotte et al (2000) Effects of Work Stress on Ambulatory Blood Pressure, Heart Rate, and Heart Rate Variability. Hypertension: Journal of the American Heart Association. 35: 880-886

[3] Mayo Clinic. Mayo Foundation for Medical Education and Research [Internet]. Rochester (MN): Mayo Clinic; c2013. Chronic stress puts your health at risk; 2013 [cited 2013 Sep 21]; Available from: http://www.mayoclinic.com/health/stress/SR00001

[4] Cleveland Clinic. The Cleveland Clinic Health Information Center [Internet]. Cleveland (OH): The Clinic; c2013. Stress Management and Your Heart; 2013 [cited 2013 Sep 21]. Available from: http://my.clevelandclinic.org/heart/prevention/stress/stressheart.aspx

[5] National Library of Medicine (US). Hyperventilation [Internet]. Medline Plus. Bethesda (MD): National Institute of Health (US); 2012 Aug [cited 2013 Sep 23]; Available from: http://www.nlm.nih.gov/medlineplus/ency/article/003071.htm

[6] Dr. Fred Meunch in: Thompson C. You’re Breathing All Wrong. Men’s Journal [Internet]. 2009 Jun [cited 2013 Sep 23];  Available from: http://www.mensjournal.com/magazine/you-re-breathing-all-wrong-20130227

[7]  UT Counseling and Mental Health Center [Internet]. Austin (TX): University of Texas; c2013. Stress Management and Reduction; 2013 [cited 2013 Sep 21]. Available from: http://www.cmhc.utexas.edu/stressrecess/level_two/breathing.html

[8] Sircar S. Principles of Medical Physiology [Internet]. New York (NY): Thieme Vitasta Publishing; 2008, pp. 268-270