Just because you're stuck on an airplane doesn't mean you can't practice your golf swing. Or rehearse a piano concerto. Or even prep to perform heart surgery.

Athletes have long used mental imagery to complement physical practice, and research indicates that going through the motions only in your head can enhance performance just as well as—and sometimes better than—actually working up a sweat.

In one study at Texas A and M, medical students learning venipuncture received 30 minutes of guided physical practice followed by either 30 more minutes of practice, 30 minutes of guided mental imagery, or no more training. When tested, the first two groups performed better than the third, and just as well as each other. The same effect was seen in students learning to suture.

Mental rehearsal can be even better than physical practice because it activates more abstract neural representations of physical skills (with less specific detail about the muscles used), reports Erica Wohldmann, a psychologist at California State University Northridge. If you physically practice your tennis backhand with a coach, and then practice it incorrectly on your own, rehearsing the wrong movements could hinder relearning the right technique later.

Mentally practicing a clumsy backhand is not muscularly detailed enough to hurt your swing. It is detailed enough to prevent forgetting what you've already learned, though. Further, having that abstract representation in your brain allows you to more flexibly apply your skills to novel scenarios—say, playing with an unfamiliar racquet.

The idea that mental imagery can improve motor performance as much as physical practice, and without the risk of interfering with correct form, seems like having your cake and eating it too. But don't give up the sweatbands just yet. For complicated tasks that rely on ongoing sensory feedback, physical practice is crucial. And besides, who wants to salsa dance only in their head? "What brings us joy," Wohldmann reminds us, "is being able to move."

All in Your Mind

Mental notes on mental imagery

• Keep it vivid: "Try to feel in as much detail as possible your own body movements when you're mentally practicing," Wohldmann says—as long as you're doing them correctly.
• Tailor your speed: When a task is new, run your simulations slowly so you can focus on the details. If you're an expert, quicker is better.
• Watch and learn: Observing others perform can activate the same motor programs in your head, making you better.