Why standing up can feel like a marathon for millions of people
In short: Postural orthostatic tachycardia syndrome, or POTS, is a complex disorder of the autonomic nervous system. It turns the simple act of standing into a physiological struggle, causing heart rates to skyrocket and blood to pool in the limbs, often leaving patients feeling lightheaded, exhausted, and unable to function normally.
POTS is a form of dysautonomia, meaning it disrupts the autonomic nervous system—the body's internal control center for involuntary functions like heart rate, blood pressure, and temperature regulation. In a healthy person, standing triggers a series of precise nervous system responses that tighten blood vessels and modestly increase heart rate to ensure blood reaches the brain against gravity. In those with POTS, this mechanism falters. The blood vessels fail to constrict efficiently, causing blood to pool in the lower body and depriving the brain of sufficient oxygenated blood.
The hallmark of the condition is an exaggerated heart rate increase upon standing: at least 30 beats per minute for adults, or 40 beats per minute for adolescents, measured within the first 10 minutes. Because the body struggles to maintain blood flow, it compensates by releasing excess stress hormones like epinephrine and norepinephrine. This chemical surge often manifests as palpitations, shakiness, and chest pain. While the heart structure itself is typically normal, the resulting symptoms—ranging from brain fog and extreme fatigue to nausea and fainting—can be profoundly disabling.
Diagnosis requires ruling out other conditions, such as orthostatic hypotension or dehydration. Clinicians typically use a 10-minute standing test or a tilt table test to confirm the heart rate criteria. While there is no single known cause, POTS is estimated to affect one to three million Americans, predominantly women, and often emerges following viral illnesses, surgery, or during puberty. Though life-changing and sometimes requiring significant lifestyle adjustments—such as increased fluid intake, compression garments, and medication—it is not considered life-threatening, though the risk of falls from fainting remains a notable concern.
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Sources
- Summary by Intellect · source: Postural Orthostatic Tachycardia Syndrome (POTS)
- Also: Postural orthostatic tachycardia syndrome
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