Michael Jackson's 'Beat It' has the optimal beat. So does 'Gangnam Style' by Psy and Lady Gaga's 'Edge of Glory.'

Research has found that at the right tempo, music can reduce the sense of exertion as well as boost motivation. Costas Karageorghis, deputy head of research at the School of Sport and Education at London's Brunel University, says the 'sweet spot' for workout music is between 125 and 140 beats per minute when people aren't trying to time their movements to the music. Previously, experts believed that the faster a person exercises, the faster the music tempo should be.

Other new studies have shown that when athletes synchronize their movements to a musical beat, their bodies can handle more exertion: Treadmill walkers had greater stamina and cyclists required less oxygen uptake. And swimmers who listened to music during races finished faster than others who didn't.

'Music can alter emotional and physiological arousal much like a pharmacological stimulant or sedative,' says Dr. Karageorghis, who has worked as a consultant psychologist to music and sports-equipment companies and for Olympic athletes. 'It has the capacity to stimulate people even before they go into the gym.'

The benefits of music seem most pronounced during low-to-moderate-intensity exercise -- in other words, it's more effective for recreational exercisers than elite athletes, scientists say. And finding just the right beat isn't difficult, as a lot of popular music falls within the optimum tempo range and most other musical genres also have music in that range, Dr. Karageorghis says. For classical music buffs, two pieces that work for him are Beethoven's Symphony No. 3 in E-flat major, known as the 'Eroica' symphony, and Mozart's Symphony No. 40 in G minor. Other qualities that make music ideal for workouts are motivational sounds and lyrics -- think the theme from 'Chariots of Fire' with its associated image of men running on the beach.

Sylwia Wiesenberg, owner of Tonique Fitness in New York City, says she keeps tempo in mind when compiling playlists for her two-hour cardio and body-sculpting class. 'The hardest part of the class is the first 15 to 20 minutes,' she says. 'I use music as my powerful instrument to push people harder,' she says.

Ms. Wiesenberg starts the class with songs that have 115 to 117 beats per minute -- such as 'The Longest Road' by Morgan Page -- then increases that to about 125 beats. Finally, the workout peaks with music at about 135 beats per minute, including 'Beautiful World' by Tiesto & Mark Knight featuring Dino. A month ago when the speakers in her studio weren't working, 'the class had a totally different atmosphere and energy,' she says. 'People were stopping.. . .I'm so dependent on the music that I don't even see a point to doing a class without the music.'

A study published last year in the Journal of Sports Medicine and Physical Fitness found that cyclists who synchronized their movements to music reduced oxygen uptake by as much as 7%. The study tested three different musical tempos on 10 men who cycled for 12 minutes at 70% maximal heart rate.

Another experiment, involving 30 people walking on treadmills, found that exercising at the same tempo as the music boosted endurance. One group of participants walked with motivational music, another with neutral music and a third with no music. Endurance increased in both groups listening to music, although the motivational music had the greatest effect. The study was published in the Journal of Sport & Exercise Psychology in 2009.

Experts say most of the benefits of working out to music come from psychological factors. 'When people run with music their rate of perceived exertion is lower than if they don't use music or other devices,' says Gershon Tenenbaum, director of the graduate program in sport and exercise psychology at Florida State University. These benefits tend to evaporate once a person begins exercising at very intense levels, he says.

Dr. Tenenbaum says similar benefits have been observed when athletes are told to imagine they are in a certain location, such as at the beach, or are exposed to particular smells, such as lavender.

David-Lee Priest, a researcher at the University of East Anglia in Norwich, England, says music is able to divert attention through a neurological mechanism. The unpleasant feedback from exercising, such as difficulty breathing, sweating or stiff muscles, is transferred to the brain using the afferent, or sensory, nervous system. Listening to music interferes with the transmission of those sensations, he says. 'Before you become aware of the fatigue the music will block out the sensations of fatigue and effort so you won't fully notice them,' he says. That blocking occurs only up to a point -- about 70% of one's maximum capacity, he says.

With resistance training, the benefit of music occurs more before one starts exercising or in between sets, Dr. Priest says. 'It's like taking a mild stimulant.. . .It will increase your heart rate and blood pressure slightly.'

In a recent study, Dr. Karageorghis and colleagues tested the effects of music on swimmers. After three weeks in which the athletes got used to swimming with ear buds, the researchers conducted three experiments using 26 collegiate swimmers who completed the 200-meter freestyle trials. They listened to motivational music, neutral music and no music. Both music groups saw a three-second improvement in performance compared to their race times without music. Although this represented just a 2% improvement, Dr. Karageorghis says it's enough to make a difference in the realm of competitive swimming.

Swimmers listening to music also reported a 10% jump in their level of motivation, compared with swimming with no music. The study, scheduled to be published in the journal Psychology of Sport and Exercise, was sponsored by swimwear company Speedo International Ltd.