Rememeber how the “Grinch” had a heart that was two sizes too small? It appears that medical malady is for real and it’s named for the famous (or infamous, depending on your point of view) Dr. Seuss character.

According to the Associated Press and Yahoo! Health, a new study shows that exercise helped improve the symptoms of patients with “Grinch Syndrome,” named for the Dr. Seuss character because most sufferers have hearts that really are “two sizes too small.” Yes. It really does exist.

About 500,000 Americans — mostly women — suffer from the condition, which is also known as postural orthostatic tachycardia syndrome. It causes such such dizziness and tiredness that many are unable to stand for long periods of time.

“The lightheadedness or fainting is also accompanied by a rapid increase in heartbeat of more than 30 beats per minute or a heart rate that exceeds 120 beats per minute, within 10 minutes of rising,” according to the National Institute of Neurological Disorders and Stroke.

Researchers in Texas gave the 18 study participants either a beta blocker or a placebo, accompanied by three months of exercise training. They found that regardless of whether the volunteers were assigned the placebo or the beta blocker, all of the patients who did the exercise training saw improvement in circulation and kidney function, according to the report published in Hypertension: Journal of the American Heart Association.