For the last two years, I’ve been challenged by a very annoying and potentially dangerous medical condition. Just recently, I finally discovered the diagnosis. Keep reading if you’re interested!
A few weeks after my final Covid booster shot, I started experiencing profound lightheadedness out on runs. It would occur suddenly. After having to “walk it off” for a minute or so, symptoms would resolve only to recur again several times per workout. I also noted periodic swelling of my legs. Additionally, I have had severe lightheadedness when getting up after being seated. (Orthostatic hypotension) To complicate the picture, I noticed occasional sudden and complete whitening of my fingers after runs, a condition called Reynaud’s Syndrome. This specifically is micro arterial vasoconstriction causing no blood flow to the extremities.
My heart rate during these episodes on my runs would be almost always 72, when normally it should be in the 130’s. I couldn’t explain this, despite my medical background and my Master’s degree education in Exercise Physiology.
Because of the slow heart rate with workouts, I feared a rhythm abnormality. This could not be ignored because of the risk of sudden cardiac death the heart stopping!) I saw an esteemed Cardiologist who is a good friend of mine who completed a full workup, including a maximal Exercise Stress Test, EKG, comprehensive blood tests and an Echocardiogram (ultrasound of my heart).
Of course, nothing abnormal could be found. He and all others with whom I’ve discussed my condition have been perplexed.
Finally last month, while talking with my nurse practitioner friend during a softball game, we discovered the diagnosis. She relayed that she had a very similar scenario while racing in long-distance mountain bike events. Except in her case, her heart rate drastically accelerated with training and racing, making her functionally incapacitated. Over many years, she saw numerous doctors of multiple specialties (primary doctor, cardiologist and neurologist.) Finally, a renowned Exercise Physiologist figured it out. The explanation: DYSAUTONOMIA!
This is dysfunction of the Autonomic Nervous System (ANS). Some of you who took biology, or anatomy and physiology class, may remember that the ANS is composed of the sympathetic and parasympathetic nervous system. The former manages the “Fight or Flight” response during stress. It accelerates the heart, for example. The latter manages normal resting body function. Among many other things, it slows the heart rate, controls digestion and maintains normalcy during periods of rest and non-stress.
Dysautonomia may present many ways. The flagship condition is called POTS or Postural Orthostatic Tachycardia Syndrome where a patient’s heart rate flies sky high when they change positions rapidly. It can be dangerous but more so it is very bothersome.
With the extreme complexity of the ANS and its diffuse and tremendously intricate involvement of virtually all body systems, it comes as no surprise that it can manifest so differently and so severely.
Depending on the symptoms, management varies. For most, patients drastically increase their intake of salts to increase blood volume and they must wear compression clothing to increase blood flow to the core and vital organs. Often they are prescribed medicine to increase their blood pressure (midodrine.)
I have a very rare situation in that again, my heart rate doesn’t rise commensurate with my workload needs. Specifically, my heart rate fluctuates back and forth from too slow to normal during exercise.
Certainly I am greatly simplifying the physiology of heart function, particularly its rate. My case probably is complicated by the great disruption in my circadian rhythm (sleep cycle) from working 24 hours shifts and the fact that I exercise tremendously longer and harder than the average dude. I’ve noticed that my heart “behaves” better after several nights in a row of good, long sleep.
I must say though that when my body must compensate with other body systems (lungs and muscle function, oxygen extraction on a cellular level, etc.), I’m getting a cumulatively fantastic training benefit. But during periods of low heart rates, it’s nearly impossible for me to push through without having to walk until my heart “switches on again.” Normally it would be twice as fast, providing the cardiac output needed.
In workouts when the dysautonomia doesn’t kick in, I feel as if I’m 25 years old and as fit as a race horse.
So the moral of the story: if one experiences multiple and varied symptoms, they should see their doctor and this complex and frustrating condition should be considered.
