What is POTS?

POTS is a condition that affects the autonomic nervous system, which regulates involuntary bodily functions such as heart rate, blood pressure, and digestion. POTS can lead to low blood volume and poor blood vessel constriction, with some symptoms including fainting, irregular heartbeats, fatigue, and more. The cause of POTS is unclear, but it can often develop after a concussion or viral illness.

"Because I have POTS, I pool blood in the vessels below my heart when I stand. My body then releases extra norepinephrine or epinephrine, which adds additional stressors on my heart, making it beat faster. Which, in turn, bring on dizziness, fainting and exhaustion," Ledecky wrote in her memoir.

According to Tae Chung, an assistant professor of physical medicine and rehabilitation at Johns Hopkins University and director of its POTS clinic, people with POTS often have difficulties transitioning from horizontal to vertical positions, which is a result of blood circulation problems.

When adults with POTS transition from horizontal to standing, their heart rates can increase by at least 30 beats per minute during the first 10 minutes of standing, Chung added. For adolescents, that number is usually 40 beats per minute. According to Chung, POTS most commonly develops in younger women.

Amanda Kaufman, supervisor of rehabilitation services at Northwell Health STARS Rehabilitation, said that POTS presents a wide range of severity and symptoms, and can be completely debilitating for some people.

"Those who have that moderate to severe [POTS] -- they're encouraged by what they see in Katie Ledecky -- but also may have reservations like, 'Oh well, I'm not trying hard enough'... where in reality, it's that they just have more of a severe case," Kaufman said.

Ledecky said she first noticed something was off at the 2015 World Aquatics Championships in Russia.  Following a team dinner, Ledecky wrote that she started to feel "extremely hot and lightheaded." Initially, Ledecky said she thought the incident was an odd fluke until she found herself feeling fatigued after workouts.

"I would have a couple of good practices, and then I would have a day or two when I had absolutely no energy," she wrote. "Some days I couldn't walk around without dizziness. I remember wrapping practice and struggling to get back to the locker room."

At the urging of her coach, Bruce Gemmell, Ledecky saw a specialist at Johns Hopkins, where she was diagnosed with POTS.

How Ledecky manages her condition

After she was diagnosed, Ledecky said she changed her diet by increasing her sodium intake and adding more hydration.

Another way to treat POTS is through reclined aerobic exercise like swimming, a coincidence Ledecky said was "kind of funny."

"What are the odds that the prescriptive exercise for my particular disease would be…more swimming?" she wrote.

According to Kaufman, when it comes to swimming with POTS, "the body has a harder time bringing the blood from the legs back up to the body, and not from the upper part of the body down to the lower part. So doing that dive into the water is actually going the opposite way."

"Getting in the pool helps to alleviate some of that stress on the body, because the water helps you be more buoyant, which creates less stress on the joints," Kaufman added. As a result, transitioning between different positions and going from horizontal to standing "is not such a dramatic change for the body."

Chung said the main strategy for treating POTS is volume expansion therapy, where the goal is to increase blood volume by drinking a lot of water and salt and using medications to retain fluid to increase blood flow.

"Although it's not a cure, their fatigue and exercise intolerance can improve with really aggressive volume expansion therapy," Chung said.

Ledecky said she currently has gotten her POTS "under control completely."

"I really just had to add salt to my diet and wear compression gear," she said. "Whenever I get sick and when I go to hot environments, I need to be especially careful to stay on top of my salt and hydration."

She also advised anyone else suffering from POTS to "trust the health professionals you're working with."

"I did that and was able to figure out what helped me pretty quickly," Ledecky said. "I understand that for some people, it's a longer process. But it's important to stay patient and work with the people around you and make sure you have good people watching out for you, encouraging you. For instance, my mom is always reminding me to stay on my salt and hydration." (Sederstrom, NBC, 8/7; Robertson, MedPage Today, 8/6; Patel, TODAY, 8/5; Dupre, E! News, 8/6)

Women's health encompasses health conditions that affect women across their lifespan, factors that influence their health and wellbeing, and women's experiences with care delivery.