Police Psychology: Intrinsic Heart Rate – A Landmark for the Ability to Engage in Rational Thought
by Doug Gentz, Ph.D. – Psychological Services
Your intrinsic (inherent) heart rate is how fast your heart would beat when you are calm and at rest if it wasn’t slowed down to your (observed) resting rate by your vagus nerve. Your resting heart rate is best measured when you’re comfortably laying down and relaxed. The “normal” resting rate for a healthy, young adult ranges from about 60 to 85 beats per minute (bpm), slightly higher on average for females than males. Individuals with well conditioned cardiovascular systems may have lower resting rates, often less than 60 bpm.
Let’s start with two systems in your body — the Sympathetic Nervous System (SNS) and the Parasympathetic Nervous System (PSNS). The sympathetic nervous system raises you up, pumps blood to your muscles, makes you heart rate go up, releases acid in your stomach to chew up the food, makes you breathe shallow and quick and all stuff so you can fight or flight. It throws your brain into the mode that causes tunnel vision, so it affect everything. Now you can’t just keep going up and up, so the parasympathetic nervous system calms you down. It releases the different hormones and stuff that calms all the body down so you can relax. They work in conjunction with each other to regulate your body and make it a mean fighting machine, or a run fast and get away from the Tyrannosaurs Rex running machine.
Your vagus nerve is the biggest nerve in your body and makes up about 80% of your PSNS. It has many connections to your aortic arch and slows your heart rate down from your intrinsic rate to your observed resting rate. If you are interested in calculating your approximate intrinsic rate you can multiply your observed resting rate times 1.349 and add 13.957. For example, if your observed resting rate is 60 bpm, multiplying by 1.349 equals 80.94, adding 13.957 = 94.897. Rounded off that’s 95 bpm. If you’re not interested in all the math you can just assume an intrinsic rate of 100 bpm. (Formula from the work of John Gottman, Ph.D.)
If your heart is beating slower than your intrinsic rate that means that your vagus nerve (PSNS nerve) is effectively pulling your heart rate down toward your observed resting rate. In other words, if your vagus nerve were inactivated while you were at rest, your heart rate would immediately go from your observed resting rate to your intrinsic rate.
So what’s the point?
If your heart rate is at intrinsic level or above in the absence of physical exertion, that means your heart rate is being accelerated by hormonal influences like anger or anxiety. It indicates that your SNS is activated enough to cancel out the slowing effect of your vagus nerve. When you’re autonomically dominated by your sympathetic system, you lose the ability to access your frontal lobes effectively – meaning you lose the ability to do a simple algebra problem in your head, the ability to use active listening skills, the ability to think creatively, and the ability to engage in effective conflict resolution.
In other words, when your heart rate exceeds approximately 100 beats per minute for emotional reasons, you will react based on training (and habit) instead of deliberate thought. Most people cannot sense when their heart rate passes 100 beats per minute. If you can consciously feel your heart beating rapidly, then it’s safe to assume that even if you believe you’re thinking rationally, you’re probably not. If the situation will allow you to safely step back, take a few breaths, and calm your nervous system, then that’s a good option. If circumstances call for an immediate reaction, then you will be depending on the quality of your training and the frequency of your practice.
And that’s how a little nerve can control the thoughts in your brain.
Gary S. Aumiller, Ph.D. ABPP
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