[ti:What Is Chronic Fatigue Syndrome?] [by:www.51星和彩票.com] [00:00.00]更多听力请访问51VOA.COM [00:00.04]Chronic fatigue syndrome is one of the most troubling mysteries in modern medicine. [00:09.00]Many years after first recognizing the disorder, researchers still do not know what causes it. [00:19.64]Now the United States' National Institutes of Health is using volunteers in a unique study. [00:29.48]The goal is to learn more about the condition, which affects an estimated 2.5 million Americans. [00:40.76]For years, Zach Ault, a father of three, enjoyed being physically active. [00:48.80]He was even training for a half-marathon. [00:52.88]He would go on long runs in hopes of competing in the race. [01:00.04]But in 2017, he took time off to recover from an infection. [01:07.16]After recovering, he tried to continue his runs but could not complete them. [01:15.88]An invisible disease began causing Ault problems. [01:20.88]He was not able to spend time with his children. [01:25.84]He had to cut back his job. [01:29.32]Even sleeping as much as 16 hours a day made no difference in his condition. [01:37.24]"His body had literally hijacked him [01:40.96]and it wasn't going to allow him to push through," said Anne Ault, his wife. [01:48.64]After months of testing, doctors announced their diagnosis of Ault's condition. [01:56.96]Chronic fatigue syndrome makes an individual feel extremely tired. [02:03.40]This fatigue lasts more than six months and becomes worse after any kind of physical exertion. [02:13.40]Patients may have difficulty standing upright. [02:18.72]They also may have trouble thinking, often described as a "brain fog." [02:26.20]Many cases go undiagnosed or misdiagnosed. [02:32.80]There are no approved treatments, or even tests to help with diagnosis. [02:40.80]There is no way to predict who will recover and who will have a severe case that lasts for years. [02:50.28]Doctors at the National Institutes of Health are looking for more clues. [02:57.48]They are interested in people who came down with the disorder [03:03.08]after an infection, of any kind, within five years. [03:09.40]About 500 patients have asked about taking part in the NIH study. [03:17.48]It starts with a hospitalization for blood and genetic tests, [03:23.84]brain imaging scans, as well as other things. [03:29.24]Researchers will examine the results before deciding who to invite back for a longer visit. [03:38.40]Zach Ault is one of the subjects in the study. [03:43.92]Reporters from The Associated Press filmed Ault beginning a test on an exercise bicycle. [03:53.48]"Go as far as you can, work as hard as you can," NIH physical therapist Bart Drinkard told Ault. [04:03.80]While Ault pedals the bike, scientists measure how his leg muscles use oxygen. [04:11.60]Afterward, doctors fit a special cap on Ault's head to measure electrical activity in his brain. [04:21.16]They then send him to spend the night in an air-tight chamber. [04:26.80]Pipes remove air from the room for additional study. [04:33.24]Scientists measure oxygen and carbon dioxide levels [04:38.12]to tell how much energy Ault is using, minute by minute. [04:44.20]"We can calculate every molecule. It's the cleanest air we have in the hospital," [04:51.04]said Kong Chen, a metabolism specialist at NIH. [04:56.00]"We're figuring out how his body adjusts to an exercise load, or a stress load." [05:04.36]The study does not offer any treatments to people with chronic fatigue syndrome. [05:10.92]But Ault says it did help him learn about the disease. [05:15.72]And it gave him ideas about how to save up his energy. [05:21.92]"It's hard not knowing if I'm going to recover, if or when," he said. [05:28.48]Until research has an answer, he says he will "hope for the best but live for right now." [05:37.56]I'm John Russell. 更多听力请访问51VOA.COM