POTS vs Deconditioning: Can Deconditioning Cause POTS?

What Is Deconditioning in POTS?

Deconditioning is what happens to your heart and circulation when you stop using them the way you used to. After 2 weeks of head-down bed rest, 12 healthy young adults lost 17% of their plasma volume, their hearts pumped 12% less blood per beat, and their tolerance for being upright fell by 24% (Levine, 1997). In 1 small study, 6 weeks of bed rest shrank the main pumping chamber's muscle by 8% (Perhonen, 2001). These studies used strict bed rest, often tilted slightly head-down, so they model severe inactivity more than an ordinary quiet stretch.

Spaceflight also makes standing harder: after shuttle missions of 9 to 14 days, 9 of 14 astronauts couldn't finish a 10-minute standing test that all of them had finished before the flight. On standing, their heart rates rose by about 35 beats per minute on average in those who finished and 51 in those who couldn't (Buckey, 1996).

With a smaller heart and less blood, each beat moves less blood, so the heart beats faster to keep blood moving. Researchers who studied POTS this way wrote that the fast heart rate "appeared to be a physiological compensatory response to the smaller stroke volume" (Fu, 2010). Our team's view goes a step further: the high heart rate in POTS is a rescue, and what it protects is blood flow to the brain.

What Does the Research Say About Deconditioning Causing POTS?

The 2019 NIH consensus lists "severe deconditioning caused by prolonged bed rest" among the things that must be excluded before diagnosing POTS, and says prolonged bed rest from any cause can itself bring on deconditioning and orthostatic intolerance (Vernino, 2021).

The Dallas group compared 27 people with POTS with 16 healthy sedentary adults. The people with POTS had smaller hearts and less blood: median left ventricular mass of 1.26 against 1.45 grams per kilogram, and median blood volume of 60 against 71 milliliters per kilogram. The authors wrote that their results "suggest that POTS per se is indeed a consequence of 'deconditioning'," which they defined as a smaller heart and low blood volume, and noted that almost all their patients had a history of physical inactivity (Fu, 2010). That comparison was made after people were already sick, so it can't show whether the inactivity came before the symptoms or after them.

At Mayo Clinic, 95% of 84 people with POTS had low fitness on an exercise test, and so did 91% of 100 people with orthostatic intolerance who didn't have POTS, after a median of 4 years of symptoms. The authors concluded that deconditioning "may play a central role" and supports retraining (Parsaik, 2012).

A Mayo Clinic-led review takes a different line: "After some initiating event, deconditioning plays a major role in sustaining POTS" (Joyner, 2008). Its authors pair the cycle of less activity and more deconditioning with "somatic hypervigilance," a heightened focus on body sensations, which our team doesn't see as the driver. Canadian guidelines list deconditioning as 1 of several mechanisms that often coexist in the same person (Raj, 2020), and that fits what our team sees: deconditioning is usually part of the picture, and rarely all of it.

Did Deconditioning Cause Your POTS, or Did POTS Cause It?

In a survey of 4,835 people with POTS, 1,933 said their symptoms began within 3 months of a specific event. Among those, the most common were an infection (41%), surgery (12%) and pregnancy (9%), and 4% named a concussion (Shaw, 2019). The NIH consensus describes 2 patterns: a sudden onset after a trigger like these, or symptoms that build slowly over a long time (Vernino, 2021). Events like these often come with days or weeks in bed, so it helps to ask whether the symptoms began before the rest or after it.

In our team's view, if your trouble standing came first and you could do less because of it, the doing less probably wasn't the cause. For many people, exercise is one of the first things to fail, and if it failed first, it's unlikely to be what started the problem. That relies on memory, and trouble with exercise is also an early sign of deconditioning, so our team backs it up with testing. If weeks in bed came first, rebuilding conditioning is how our team builds tolerance back. In both cases, you'll still need to rebuild strength and tolerance once the underlying problem is handled.

Is It POTS or Am I Just Out of Shape?

Both can leave your heart pounding and your energy gone. These questions help tell them apart:

• Do symptoms come on when you stand still and ease when you lie down? That's the POTS pattern: a sustained heart rate rise of at least 30 beats per minute (40 at ages 12 to 19) within 10 minutes of standing, without a drop in blood pressure, with symptoms upright for at least 3 months (Vernino, 2021). Severe deconditioning can cause it too, which is why the next 2 questions matter.
• How did it start? A sudden start after an infection, concussion, surgery or pregnancy fits the trigger pattern the NIH consensus describes (Vernino, 2021). If the symptoms began before any time in bed, our team reads that as pointing away from simple inactivity.
• Did a stretch of bed rest come first? Then deconditioning has to be considered before POTS is diagnosed (Vernino, 2021).
• What happens when you train? In our team's experience, when someone has done a well-dosed program for about 3 months and the symptoms haven't moved, it's a sign to step back and look for what changed their physiology in the first place.

An exercise test alone can't settle it, because in the Mayo study, nearly as many people with orthostatic intolerance but no POTS tested as deconditioned (Parsaik, 2012). A tilt table test shows what your heart rate and blood pressure do upright, and our team also measures blood flow to the brain and the carbon dioxide you breathe out, to look for what's driving the heart rate.

Can Deconditioning Be Reversed?

Much of it can be reversed with training. In the Dallas group's study, 3 months of training increased heart muscle mass by about 12% and blood volume by about 7%, and 10 of the 19 people who finished no longer met POTS criteria (Fu, 2010). The program started on a recumbent bike, rowing machine or in a pool and moved to upright exercise, and patients were also encouraged to take more salt and water and raise the head of the bed, so the authors couldn't credit the training alone. In a community registry, 71% of the 103 people who completed a similar program no longer qualified for POTS, which is about 29% of the 251 who enrolled (George, 2016). Propranolol, a heart rate medicine, lowered the standing heart rate as training did, but quality of life improved only with training (Fu, 2011). Canadian guidelines give exercise training a strong recommendation, based on moderate-quality evidence (Raj, 2020). For how to exercise with POTS, see why standard exercise advice fails POTS patients.

These programs already work around upright intolerance by starting recumbent. Our team's concern is the people who still stall there. Fu's finding predicts that training should help, and it does for many people. Our team's view is that when it doesn't, the fast heart rate is compensating for a different shortfall, the way the brain holds its own blood flow steady, and exercise alone won't settle that.

How Our Team Rebuilds Conditioning in POTS

Our team works through the mechanism that's failing and then stacks exercise on top, at a dose your body can handle. Check with your clinician before starting, and stop for fainting or chest symptoms.

• Hold on to what you can do. Keep whatever level of activity you have now, because in our team's experience, the more ground you lose, the more you have to make up later.
• Use the pool with someone there. Water pressure pushes blood from your legs back toward your chest: in studies of healthy men, immersion raised the amount of blood the heart pumps per beat and lowered heart rate (Norsk, 1986; Gabrielsen, 1993). Fainting in water is dangerous, so only swim with someone present and with your clinician's OK.
• Start lying back. Our team often starts people lying on the floor and works up to an inclined bench, at a dose your body tolerates.
• How our team positions the hips. On a standard recumbent bike, some people appeared to keep pooling blood in their legs while pedaling, so our team uses setups that keep the hip angle more open.
• How our team handles carbon dioxide. Our team keeps the carbon dioxide you breathe out in a steady range during exercise while training the reflexes that hold brain blood flow steady, which is where many people struggle most.

POTS and Deconditioning: FAQ

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