POTS: When Gravity Becomes the Enemy

Postural Orthostatic Tachycardia Syndrome (POTS): When Gravity Becomes the Enemy

For most people, standing up is a thoughtless action. For someone with POTS, it is a physiological event.

The heart races. The room may spin. Fatigue quickly sets in, accompanied by brain fog, trembling, or shortness of breath. You sit down, and the symptoms slowly improve. But the next time you stand, the cycle repeats.

Often, doctors run cardiac tests—EKGs, echocardiograms, Holter monitors. And almost always, the results are "normal." The heart structure is fine. The rhythm is fast, but otherwise healthy.

So why does standing feel so incapacitating?

The problem is not the heart. It is the wiring.

POTS is not a cardiac condition. It is a condition of the autonomic nervous system.

When a healthy person stands up, gravity pulls blood down into the legs. The autonomic nervous system instantly detects this and signals the blood vessels in the lower body to constrict (tighten). This pushes blood back up to the heart and brain. At the same time, heart rate increases slightly—usually by 10 to 15 beats per minute—to maintain steady blood flow.

In POTS, this process breaks down.

The signal for the blood vessels to constrict is weak, delayed, or missing entirely. This is called sympathetic withdrawal. Because the vessels don't tighten, blood pools in the lower body.

The brain quickly senses a drop in blood flow and sounds an alarm. It releases an emergency surge of adrenaline to force the heart to beat faster and harder, compensating for the lack of vascular squeeze.

The racing heart is not the disease. It is the body's desperate attempt to keep you conscious.

Why the symptoms are so widespread

Adrenaline is powerful. When the body relies on adrenaline surges just to stand upright, the side effects are systemic.

This explains the "anxiety-like" symptoms common in POTS—the tremors, sweating, chest tightness, and hypervigilance. It is physiological panic driven by poor blood flow, not psychological distress.

Furthermore, because the autonomic nervous system regulates digestion, temperature, and sleep, when the system is strained by simply maintaining posture, those other functions often degrade. Digesting a meal requires blood flow to the gut; in POTS, that blood is often pooling in the legs, leading to nausea, bloating, and motility issues.

Why standard testing misses it

Most clinical testing assesses the body at rest. A patient lies on an exam table, their blood pressure is checked, an EKG is run. In this horizontal position, gravity is not a factor. Blood flow to the brain is easy. The autonomic nervous system does not have to work hard.

POTS is a dynamic failure. It only appears when the system is challenged by posture.

How autonomic testing changes the picture

To understand POTS, you have to measure regulation, not just structure.

Autonomic testing evaluates how the sympathetic and parasympathetic nerves coordinate during postural changes. It distinguishes between a racing heart caused by poor vascular tone versus one caused by excessive adrenaline or low blood volume. By identifying the specific mechanism of failure, treatment can shift from merely lowering the heart rate to actually improving vascular regulation.

Autonomic testing is coming soon

At-home autonomic testing is currently in development. Sign up to be notified when testing becomes available, and finally get the objective data you need to understand your symptoms.