In his article, "Music in Sport and Exercise: Theory and Practice" Dr. Costas I. Karageorghis, Ph.D, a Sport and Exercise Psychologist at Brunel University in England, suggested four key ways in which music can enhance your athletic performance.

1.    Dissociation: Getting Away From It All
 What's going through your mind as you head into that thirty-seventh lap around the track or climb that unending flight on the stairmaster? Let's face it, repetitive exercise can be boring. And boredom can make you feel more fatigued than you really are. During repetitive exercise, music can focus your thoughts and divert attention away from fatigue and boredom, making the experience seem more pleasurable.

2.    Mood Music
If hearing the theme song from the first Rocky movie puts you in the mood to go a couple of rounds with a side of beef, Dr. Karageorghis knows why. "Music alters arousal levels and can therefore be used as a form of stimulant prior to competition," he wrote. For over-anxious athletes, relaxing music can be used as a sedative to calm pre-game jitters.

3.    Music Increases Endurance.
Adding music to a workout has been shown to increase the duration of the workout. A study conducted at the University of Kansas asked 30 student participants to engage in an aerobic exercise activity of their choice on two separate occasions. During the first session, participants were instructed not to listen to music while exercising. During the second, each subject was allowed to listen to music of their choice while exercising. Of the 30 participants, 29 showed a significant increase in exercise when music was used.

4.    Smoother Moves
"Music can enhance the acquisition of motor skills and create a better learning environment," wrote Dr. Karageorghis. "There is evidence from both gymnastics and swimming in support of this"
"Rhythm has a powerful, organizing effect on motor skills. It helps synchronize movement almost immediately." Michael H. Thaut, PhD, told Prevention in August 1999. As director of the Center for Biomedical Research in Music at Colorado State University, Thaut has conducted research
involving people with neurological movement disorders.
 

Choosing Your Music Wisely
Not all exercise music is created equal. Several key factors influence the motivational qualities of music.

The Rhythm is Gonna Get You
To get the most out of your music, choose something with  strong rhythmic qualities that match the activity at hand as well as a tempo which matches the predicted heart rate.

The Medical & Sports Music Institute of America, Inc. (MSMIA)  creates exercise tapes in an extensive array of tempos. You choose a tape depending on your fitness level, your target heart rate and the activity in which you are engaged. According to the MSMIA, the tapes act like cruise-control on your car. Just walk, cycle, cross-country ski or whatever to the beat on the appropriate tape and you end up with the heart rate you want.

Music That Grips and Invigorates You
"The melody and harmony of the music should promote a positive mood state; that is, they should energize the listener and increase vigor," wrote Dr. Karageorghis.

A study conducted at Brunel University College in England compared the effects of "relaxing" versus "stimulating" music on grip strength. Subjects showed higher grip strength after listening to "stimulative" music, less grip strength when listening to white noise and the least grip strength when listening to sedative music.

At the Human Performance Laboratory at Truman State University in Kirksville MO, twenty-nine college males performed a 60-second situp test on three separate occasions, once with no music, once while listening to "Adagio for strings" by Samuel Barber, and once to the sound of  Metallica.While results showed no difference between the number of situps done in 60 seconds of silence and the number done to 60 seconds of strings, the performance picked up significantly during the Metallica minute.

The Association Factor
Your previous exposure to music will have an effect on your present response to it so choose music that has positive personal associations for you. Ideally, the music should be somehow linked with physical activity either through the lyrics or its association with other media such as film or TV, e.g. the Rocky theme.

The Two V's 
Variety in the music tends to maintain athletes' interest in the activity.

Volume of the music should not be drowned out by the noise of the exercise environment.

Now you have the tools to make music a powerful exercise ally. So the next time you are heading out for a run or to the gym and you reach randomly for a tape to pop into your walkman, take an extra moment to stop and evaluate whether it is the most effective soundtrack for your workout.

Sources: 
"Effects of Preferred Music Listening on the Exercise Endurance Of Well College Students." Mike D. Brownell. The University of Kansas

"Effect of Music on Muscular Endurance in College-Aged Males." Steven Berstein, Human Performance Laboratory, Truman State University, Kirksville,MO. IAHPERD Journal Volume 31. No.2 Spring 1998.

"Got Pain? Got the Blues? Try the Music Cure." Sari Harrar. Prevention, August 1999 v51 i8 p100

The Medical & Sports Music Institute of America, Inc. (MSMIA).http://www.yourpacemusic.com/

"Music in Sport and Exercise: Theory and Practice" Dr. I. Karageorghis, Ph.D.