Not everyone can exercise. People with muscle-wasting diseases and movement disorders, the frail, the very obese and post-surgical patients are among those who face a significant challenge when it comes to working out.

But what if a drug could stimulate the body into producing some of the same effects of exercise — more endurance and weight control, for example — without the need to run a single step? Such a pill may be on the way. Several scientists are testing compounds that apparently can do this.

“Our goal is to understand these circuits,” said Ronald Evans, director of the gene expression laboratory at the Salk Institute for Biological Studies in La Jolla, Calif. Salk scientists have been working since 2007 on a chemical compound, known as 516, that mimics the effects produced by exercise by triggering a specific genetic circuit, “a back door into the exercise genetic network,” Evans said.

Other scientists are studying compounds that work differently from 516, but with the same aim: To give the benefits of exercise to people who aren’t able to do it. Ali Tavassoli, a professor of chemical biology at Britain’s University of Southampton, has discovered a drug known as compound 14 that spurs cells into metabolizing sugar, which produces energy.

Evans has targeted 516 for people with Duchenne muscular dystrophy, an approach that he believes offers the best chance for FDA approval. But the drug, now undergoing a safety study, has “a potentially wide application,” he said, including for amyotrophic lateral sclerosis, Parkinson’s disease and Huntington’s disease.