现在还只是老鼠，不过将来人也可以吃颗药就能加强耐力了。
http://sciencenow.sciencemag.org/cgi/content/full/2008/731/3Personal Trainer in a Pill
By Lauren Cahoon
ScienceNOW Daily News
31 July 2008
Want to run a marathon but too lazy to train? Perhaps you can take a pill someday. Scientists have found compounds that, when taken orally, dramatically increase endurance in mice, including one that works without any exercise.
The traditional way to build endurance is aerobic exercise, which increases the ability of skeletal muscles to burn fat effectively. A key protein in this process is PPARδ. When activated, it triggers a key network of genes that burn fat and hoist stamina. Last year, a research team led by Ronald Evans of the Salk Institute for Biological Studies in San Diego, California, genetically engineered mice with increased PPARδ activity; they discovered that these “marathon mice” had almost double the running endurance of regular mice.
Although driven athletes might consider gene therapy, casual jocks would likely prefer a pill. Yet when Evans and his colleagues recently gave a PPARδ-boosting drug to normal adult mice, the rodents developed no greater stamina than nondoped counterparts--until the researchers had the animals combine the drug with a workout routine. Then the drugged mice’s endurance shot through the roof: They ran about 70% farther than trained mice given a placebo, and their running times were similarly increased, Evans’s group reports online today in Cell.
Given that exercise was needed to kick the PPARδ drug into high gear, the research team wondered what would happen if they tricked the body into thinking it were exercising. They gave mice a drug--AICAR, which has been used in clinical trials for various diseases--that upped AMP-activated protein kinase (AMPK), an enzyme that becomes activated during a workout. These “couch potato” mice got an instant boost of endurance of up to 44%--without any form of exercise training. “We did not expect you could create exercise in a pill,” says Evans. But after 4 weeks on the drug, the mice behaved as if they had exercised every day.
Either exercise or one of its direct products, AMPK, triggers a pathway that boosts the endurance-promoting genes in the muscles, Evans concludes. And now that pathway can be manipulated--or exploited. “It’s a little bit scary,” says Mark Tarnopolsky, director of the Neuromuscular and Neurometabolic Disorders Clinic at McMaster University Medical Centre in Ontario, Canada. “Unfortunately, a lot of athletes will think they can use drugs to enhance performance.” But he adds that for people with "sedentary" diseases such as obesity or diabetes, the drugs are an exciting development.
So far, neither drug has been tested for increasing endurance in people. But even if they did work in humans, they would only boost your ability to run faster or farther--not your desire to do so, says Sebastian Jorgenson, an exercise physiologist at the University of Copenhagen in Denmark. “Even if you have so much capacity, if it’s not being used, what does it matter?” he says. And Jorgenson notes that the drugs aren’t really necessary. “The cure has been there for millions of years,” he says. “It’s called a balanced diet and exercise.”