A little secret all regular exercisers know is that sometimes you have to fake it. There are days when even the most confirmed fitness fanatic feels like lying sprawled in a motionless heap.

Occasionally this feeling should be heeded, and what you need most is rest. But more often than not, all you need to get moving is a little Chuck Berry. If Vivaldi is more to your liking, or UB40 or Cole Porter, great. Music is, after all, a matter of personal taste. But it is also a universally acknowledged tool for enhancing rapport with your body and helping transcend physical limits.

"The music-movement connection goes back to the days when humans first beat on drums," says physician Bruce Becker, a rehabilitation specialist in Eugene, Ore., who uses music to help people recovering from injuries reconnect to their bodies. "Musical rhythms tap into some of our more primitive brain centers and act to override some of the conscious centers that control pain and fatigue."

Instead of fixating on how your shoes feel or if your fingers are cold, he says, "music can take you deeper," to a plane where your body and the rhythm connect. With animals, sounds can affect hormonal release. "Dairy farmers have known for years that music in the barn helps cows generate more milk," Becker notes. "Obviously, music can enhance humans' physical experience, too."

Many top athletes use music to inspire peak performance. Champion diver Greg Louganis reportedly played "Believe in Yourself" from "The Wiz" 15 minutes before he won two gold medals in the 1984 Olympics. Olympic jumper Willie Banks set a world record moments after hearing Mick Jagger sing "Start Me Up."

Average exercisers find that music can make a workout seem easier, concluded a study at Ohio State University's College of Medicine. People using a treadmill reported a lower level of perceived exertion when listening to music they liked than when listening to music they didn't like or not listening to music at all. "Their bodies were working as hard," says biochemist Gopi Tejwani, an associate professor in the departments of pharmacology and anesthesiology. "The biochemical parameters, such as how hard the muscles are working or how fast the heart is beating, did not change. Only the psychological perception changed."

Music can also help you learn a sport faster and protect you from injury, some experts contend. "Normally, it takes weeks to learn to move the muscles in the same sequence with the correct speed and accuracy," says Boston podiatrist and sports medicine specialist Ira Grenadir. "But with music you can get the same effect in minutes. By concentrating on the rhythm, you accelerate the learning process in mastering a sport and help your body discover the best biomechanical way to move. Your body moves with greater synchronization and efficiency and gets rid of extraneous muscle contractions. This makes your joints more stable and decreases your risk of injury."

To feel this natural fluidity that comes from moving in sync with music, he suggests trying to walk to "your basic, amorphous cocktail party music, like 'The Girl From Ipanema' . . . Walking is a very syncopated two-beat similar to a bossa nova." Nearly anyone can click into this rhythm, he says.

Moving at specific tempos can be helpful to patients who are recovering from injuries. "Say you've had a heart attack and your doctor tells you that you're ready to go out and walk at a 3-mile-per-hour pace, but you have no idea how fast that is," says James Sundquist, whose Oregon-based company, Medical and Sports Music Institute of America, produces Music in Sync audio tapes designed to help exercisers maintain a workout rate that will produce a desired target heart rate. "If you walk in time to music scored at 120 beats per minute, you'll be doing exactly what the doctor ordered. Also, walkers have a tendency to start fast, then drag their feet. But if they're listening to music, they'll maintain their pace."

The best workout music is "energetic and motivational, with positive lyrics and a good melody," says Richard Petty, president and founder of Power Productions, a Gaithersburg- based company that manufactures tapes for aerobics instructors. "Each individual has to decide what motivates them and what tempo they want." Bodyworks appears on alternate Tuesdays.