In a series of startling experiments in mice, the drugs improved the ability of cells to burn fat and retain muscle mass, and they substantially prolonged endurance during exercise. Using one of the compounds for just a month, even sedentary, couch-potato mice improved their endurance running by a staggering 44%. Some mice that combined a month of exercise with the other drug bolstered their long-distance running by about 70% over untreated mice.
One of the drugs is already in late-stage human trials for other purposes, and the mouse experiments raise hopes for new strategies to protect people against obesity, diabetes and muscle-wasting diseases such as muscular dystrophy.
Researchers say the drugs might benefit people who are ill in bed or wheelchair users who "can't exercise, and this would give them some of the benefits," said Joseph Hornyak, associate professor of physical medicine and rehabilitation at the University of Michigan at Ann Arbor. But the pills would be unlikely to provide all the benefits of real exercise.
"People who exercise have lower levels of depression and higher bone density," said Prof. Hornyak. "Whether or not this pill would confer those benefits, we don't know."
